Vision Bible College

Cornucopia Project

Campus Development Series Booklet One: Hand Dug Well

Construction Plans and Technical Manual

By G. A. Lane Campus Development Project Manager

Published by

Vision Bible College Support Society Naktiguda Village, Kalahandi District, Orissa, India

Copyright MMXV by VBCSS - © 2015, All Rights Reserved

Unless otherwise noted all graphics are rendered by G. A. Lane for the purpose of this booklet and may not be reproduced without written consent.

Campus Development Series: Book One 2

John 4:1-30

Jesus and the Samaritan Woman 4:1 Jesus learned that the Pharisees had heard, "Jesus is baptizing and making more disciples than John" 2(though Jesus himself didn't baptize them — his disciples did). 3 So he left Judea to return to Galilee. 4 He had to go through Samaria on the way. 5 Eventually he came to the Samaritan village of Sychar, near the parcel of ground that Jacob gave to his son Joseph. 6 Jacob's well was there; and Jesus, tired from the long walk, sat wearily beside the well about noontime. 7 Soon a Samaritan woman came to draw water, and Jesus said to her, "Please give me a drink." 8 He was alone at the time because his disciples had gone into the village to buy some food. 9 The woman was surprised, for Jews refuse to have anything to do with Samaritans. She said to Jesus, "You are a Jew, and I am a Samaritan woman. Why are you asking me for a drink?" 10 Jesus replied, "If you only knew the gift God has for you and who I am, you would ask me, and I would give you living water." 11 "But sir, you don't have a rope or a bucket," she said, "and this is a very deep well. Where would you get this living water? 12 And besides, are you greater than our ancestor Jacob who gave us this well? How can you offer better water than he and his sons and his cattle enjoyed?" 13 Jesus replied, "People soon become thirsty again after drinking this water. 14 But the water I give them takes away thirst altogether. It becomes a perpetual spring within them, giving them eternal life." 15 "Please, sir," the woman said, "give me some of that water! Then I'll never be thirsty again, and I won't have to come here to haul water." 16 "Go and get your husband," Jesus told her. 17 "I don't have a husband," the woman replied. Jesus said, "You're right! You don't have a husband — 18 for you have had five husbands, and you aren't even married to the man you're living with now." 19 "Sir," the woman said, "you must be a prophet. 20 So tell me, why is it that you Jews insist that Jerusalem is the only place of worship, while we Samaritans claim it is here at Mount Gerizim, where our ancestors worshiped?" 21 Jesus replied, "Believe me, the time is coming when it will no longer matter whether you worship the Father here or in Jerusalem. 22 You Samaritans know so little about the one you worship, while we Jews know all about him, for salvation comes through the Jews. 23 But the time is coming and is already here when true worshipers will worship the Father in spirit and in truth. The Father is looking for anyone who will worship him that way. 24 For God is Spirit, so those who worship him must worship in spirit and in truth." 25 The woman said, "I know the Messiah will come — the one who is called Christ. When he comes, he will explain everything to us." 26 Then Jesus told her, "I am the Messiah!" 27 Just then his disciples arrived. They were astonished to find him talking to a woman, but none of them asked him why he was doing it or what they had been discussing. 28 The woman left her water jar beside the well and went back to the village and told everyone, 29 "Come and meet a man who told me everything I ever did! Can this be the Messiah?"

30 So the people came streaming from the village to see him. (NLT)

Campus Development Series: Book One 3

Campus Development Series Booklet One: Hand Dug Well

Construction Plans and Technical Manual

INTRODUCTION: These Campus Development Series booklets are prepared in order to provide a set of detailed plans of the various aspects of development and construction for facilities that would be used by Ministry organizations. Such facilities might include Educational Campuses for Bible studies, Residential Accommodations for students and faculty, Vocational Training Programs and Workshop Areas, Orphanage & Primary Educational Facilities for Children, and Health Services Centers, to consider a few possibilities. The successful development of these types of facilities requires a broad range of planning to encompass many elements from the overall architectural design to the specific details of construction. Because the ultimate purpose for these facilities is to provide for human occupation and use, it is inevitable that two of the most essential aspects of the infrastructure planning are to provide a proper, sufficient water supply and also a well designed septic waste disposal system. These two infrastructure elements are so closely related that they should actually be constructed simultaneously. As much as it is possible, the plans for the construction of the water supply and septic systems will be presented in a logical and mutually progressive order. However, it is actually necessary to have some water supply available at the development site in order to perform the construction tasks of building the septic tank(s) and other features of the architecture. Therefore, this booklet in the series will begin with the plans for constructing a primary hand dug well to provide this first water supply for the remaining construction. The overall plans that will be shown in this set are prepared more specifically for the development of a permanent Campus Facility for Vision Bible College of Naktiguda Village, which is located in Kalahandi District, State of Orissa, India. This is an area of the country within the tropical monsoon region, for one, and also it is a significant distance inland from the Eastern Coast in the uplands where the agricultural potential is rich. Because of this, there is a very good supply of rainwater that can be harvested during the monsoon rain season, and this harvest system is a significant element of the infrastructure design. In other locations that do not experience this regular seasonal rainfall, there will inevitably be a need to modify the infrastructure to depend more on the treatment of groundwater for the principal water supply. Likewise, while these plans will present the designs for horticultural / agricultural areas as vocational training activities, there may be a need to adjust the basic plans for other types of facilities such as Health Services Centers or Orphanages / Primary Schools. Never-the-less, the basic plans will provide a great advantage to those who are working to develop a variety of similar facilities.

THE HAND DUG WELL: The purpose of this booklet is to present the Construction Plans for a Hand Dug Well. The discussion of those technical details should be relatively brief as they are illustrated with appropriate drawings and photographs. However, in order to also provide a sufficiently comprehensive Technical Manual to ensure safe and proper construction as well as the extended life and sustainable use of the well it is necessary to include a discussion of various concerns regarding, site selection and soil conditions, local groundwater quality, structural tolerances, and water treatment practices. In addition to this, a brief glossary of terms is included. The discussion also includes a listing of materials & tools required for the construction and, as much as

Campus Development Series: Book One 4 possible, an estimate of the cost of these items and the related labor and logistics costs to successfully complete the project in the rural part of Kalahandi District, Orissa where the Vision Bible College Campus is to be located. Consequently, this booklet should be a resource that is kept on file as a reference for those who will work in the future to manage and maintain the water supply system for the facility. Figure 1 below shows the basic features of most common dug wells. The geology / soil conditions into which wells are dug may vary greatly, so although these features in the drawing are common, they do not represent all conditions encountered by all wells. Although variations in these details exist, these terms can be

used to describe the common features of most hand dug wells. [1]

A Glossary of Terms

Annular seal: The annular seal is the material between the borehole wall and the casing, usually placed near the land surface and is designed to keep surface water and other potential contamination out of the well. Materials commonly used include bentonite (a sticky clay), and neat cement grout (cement and water with no sand).

Aquifer: An aquifer is a geologic unit (sand and gravel, sandstone, limestone, or other rock) that will yield usable amounts of water to a well or spring.

1 Figure 1 and related glossary of terms adapted from, “Typical Water Well Construction and Terms,” (Butte, Montana: Ground Water

Information Center, Montana Bureau of Mines and Geology, Montana Tech of The University of Montana, 1998.)

Via: http://mbmggwic.mtech.edu/sqlserver/v11/help/welldesign.asp. (Accessed November 14, 2014)

The portion of the well that rises above

ground level is typically called a “Well

Head” on bore wells, and for Dug Wells

is referred to as the “Stand Up.” Land Surface

Ground Level

Annular Seal

Biologically Active Soil Layer

Sand & Gravel Layer

Clay Layer

Aquifer

Zone Water Saturated

Area of the

Aquifer

Solid Shale / Bedrock Level Figure 1

Drawdown

Cone

Static

Water

Level

Pumping

Water

Level

Well Casing

Intake Chamber

Filtration Zone

Water Levels and

Well Depths are

Generally Measured

From Ground Level

Draw

Down

Well Shaft

Campus Development Series: Book One 5 Drawdown: The drawdown in a well is the difference between the pumping water level and the static (non-pumping) water level. Drawdown begins when the pump is turned on and increases until the well reaches "steady state" sometime later. Therefore, drawdown measurements are usually reported along with the amount of time that has elapsed since pumping began. For example, "The drawdown was 10 feet at 1 hour after pumping began."

Drawdown cone: The depression in the water table near the well that is caused by pumping is called the "drawdown cone" or sometimes the "cone of depression". When the well is pumping, water levels are drawn down most near the well and the amount of drawdown decreases as the distance from the well increases. At some distance from the well at any given time there is a point at which the pumping does not change the water table and the drawdown is zero.

Measuring point: Water levels in wells are usually reported as depths below ground level, although the measuring point can be any convenient fixed place near the top of the well. In Figure 1, the measuring point is at ground level. The altitude of the measuring point is commonly recorded so that static water levels can also be reported as altitudes.

Pumping water level: The pumping water level is the distance from the land surface (or measuring point) to the water in the well while it is pumping. The time that the pumping water level was measured is usually recorded also. For example, "The pumping water level was 85 feet below land surface, 1 hour after pumping began."

Intake Chamber / Filtration Zone: All wells are open to the aquifer so that water can enter the well. Most Hand Dug Wells use a base of gravel at least three feet deep to provide a porous area through which water may filter into the well shaft. It is possible to place the solid / sealed well casing directly on top of the gravel if it is well compacted to prevent settling. Another common method of creating the Intake Chamber is to construct the lowest level of the casing from a porous cement or similar material that allows water to flow into the shaft, and then also fill the chamber with small gravel to provide filtration.

Recovery Rate: The rate at which water from the aquifer infiltrates the Intake Chamber while we're pumping water out

of the well. Since the "recovery rate" of a well describes the rate at which water runs into the well, a well recovery rate

also defines the rate at which water can be pumped out of a well without pumping the well down so far that the pump

"runs dry".

Static water level: The static water level is the distance from the land surface (or the measuring point) to the water in the well under non-pumping (static) conditions. Static water levels can be influenced by climatic conditions and pumping of nearby wells and are often measured repeatedly to gain information about how aquifers react to climatic change and other usage in the area.

Water table: The top of the saturated part of a water-table (also known as an unconfined) aquifer. Below the water table, pore spaces (or fractures) in the geologic media are filled with water. Above the water table, the pore spaces are filled with air.

Well Shaft: the hole dug to construct a well. Most well shafts for dug wells are greater than one yard in diameter.

Well Casing: Stone or concrete wall placed in the well shaft to keep it from collapsing. The casing should be water proof to prevent seepage into the shaft at levels above the Intake Chamber. Also, the casing is sealed to the shaft wall near the land surface with the annular seal.

Total depth: The total depth of the well is the distance from land surface to the bottom.

Yield: The amount of water measured in gallons per minute a well will produce when pumped.

Campus Development Series: Book One 6

CONTAMINATION CONCERNS: Hand Dug Wells are usually designed to function in a range between 20 and 50 feet deep, and even sometimes at very shallow depths less than 20 feet, and because they are relatively shallow compared to Bore Wells they have a higher risk of becoming contaminated from surface contaminants and pathogenic biology found in upper layers of the soil. Most of the biological contamination occurs as a result of an improper Annular Seal around the top of the well casing, which allows water born contaminants to seep down along the outside of the casing into the Intake Chamber. Chemical contaminants in deeper layers of soil can also enter the Intake Chamber in this manner. Another way that contaminated water enters a well is by leaching through the casing material to seep down along the inside wall of the casing. Both of these problems are easily prevented by the use of proper design features and construction methods. The most essential feature is that the Well Casing material is watertight. If possible the casing should be sealed from the outside with some form of watertight barrier between the shaft wall (surrounding earth) and the casing itself. This space is referred to as the Annular Space. A most desirable material to use for this seal is a cement grout mixture of Bentonite Clay and Portland Cement placed along the outside of the casing from the Intake Camber to the top of the well. Normally, in a case where the shaft wall is intended to be used as the outer form for In-Situ Ferrocement placement, there would be no space between the earthen wall form and the casing to place any additional materials. However, in order to include the waterproofing barrier, a technique using a simple Slip Form is possible to create a narrow Annular Space (about 1 ½ ”) between the earthen wall and the cement casing where the Bentonite / Cement Grout slurry can be added. Figures 2, a & b, below show the basic method and tool for doing this. Note that in order to have adequate working space inside the Well Shaft for the placement of the Ferrocement casing, the shaft diameter should be at least 4 feet.

The Slip Form is constructed using a 1/8”

thick plate metal rectangle that is 2’ high by

3’ wide with two wooden spacers at 1” by 1

½ ” mounted vertically to its backside.

Front View

Back View

2’

3’

Spacers are

1 ½” by 1 ½ ”

To create a 1 ½ ” offset of the

Ferrocement from the shaft wall

that becomes the Annular Space into

which the Bentonite / Cement Grout

will be poured.

Spacers are mounted to the backside of the

metal plate using flathead screws and epoxy

glue.

Metal plate is slightly curved to match the

outside circumference of the casing.

Figure 2a

Campus Development Series: Book One 7

The placement and working of Ferrocement using this technique is not difficult if the cement is

prepared with a proper Slump. [2]

Generally, a relatively stiff workability (between 2” – 3” slump) is desirable for Ferrocement tank wall construction. The key to determining the right stiffness will be the workability state at which the cement can be thoroughly consolidated without collapsing or flowing away from the desired form. With careful tamping and agitation this consolidation can be achieved with relatively stiff mixtures. Similarly, the Bentonite / Cement Grout must be mixed in proper proportions to be workable and

perform its intended function in the long term once it sets.[3]

Sodium Bentonite is one of a family of

2 Concrete Slump Test: http://www.aboutcivil.org/concrete-slump-test.html (Accessed April 2, 2015)

3 Cheah Chee Ban, Mahyuddin Ramli, “Optimization of Mix Proportion of High Performance Mortar for Structural Applications,” (Penang,

Malaysia: Sustainable Housing Research Unit, School of Housing, Building and Planning, University Sains Malaysia, American J. of Engineering

and Applied Sciences 3 (4): 643-649, 2010.) Via:

http://www.google.com/url?url=http://www.researchgate.net/profile/Chee_Cheah/publication/49619589_Optimization_of_Mix_Proportion_of_High_

Performance_Mortar_for_Structural_Applications/links/00b7d52ce5b5658787000000.pdf&rct=j&frm=1&q=&esrc=s&sa=U&ei=LSceVdDUMpHUg

wT--oDoAg&ved=0CBsQFjAB&sig2=5kT4LmX0ykkyf0ST1LuLyQ&usg=AFQjCNE0xv2LF7dNdsTVSXBF4VDXfYJcAA .

(Accessed April 2, 2015)

The Slip Form is used by rotating it around the Shaft Wall to

provide a backup form for the placement of Ferrocement. The

casing will be built up in rings at 2’ tall, working quickly to

ensure that the previous ring is not too well set so that each

consecutive ring will bond / consolidate with it to create a

monolithic – solid and watertight – concrete pour.

Top View

The trailing edge of the Slip Form remains

about 2”-3” inside the area of Ferrocement

that has already been placed.

Once the Annular Space has been created and the

Ferrocement of each consecutive ring is sufficiently

stiff to provide retention, the slurry of Bentonite /

Cement Grout is poured into the void. This is done

prior to re-setting the Slip Form to continue work on

the next ring. Note that this slurry is poured to a depth

just under the top edge of the Ferrocement ring.

The Slip Form is in

place to begin the

second ring of

Ferrocement. It is

possible to work with

the tall vertical rebar

reinforcement

members in place.

However, the

remaining horizontal

rings of rebar and the

iron mesh are added

up to 2’ (the top of the

Slip Form) as each

ring is formed.

The Ferrocement and also the grout slurry are

placed directly onto the firmly compressed

gravel of the Intake Chamber with only a layer

of moisture barrier laid down to prevent the

flow of these materials down into the porous

rock as they are setting up.

The Intake Chamber

composed of firmly

packed small gravel

is at least 3’ deep.

Figure 2b

Campus Development Series: Book One 8 bentonite clays. It is a chemically inert, organic material that results from the decomposition of volcanic ash and which is mined in powder form. When mixed with water, powdered sodium bentonite may expand up to 15 times its original bulk to produce a thick, colloidal, jelly-like goop that is impermeable to water and chemical flow. When this colloidal substance is mixed with Portland Cement the resulting slurry mixture is easy to pour into formed spaces. And like concrete, the mixture obtains mechanical strength and durability when set, thereby losing its plasticity and susceptibility to wash-out in the presence of flowing water. The ratios for mixing the Ferrocement and the Bentonite / Cement Grout will be given at a later point. Naturally, the Annular Seal at the top of the well is the primary concern for preventing biological pathogens and ground contaminants from entering the well. The procedure for making this seal is a continuation of the method used to fill the Annular Space from the bottom of the well shaft, except that rather than being only 1 ½” wide, the Annular Seal is opened up to be at least 1’ wide. The actual depth of the Annular Seal from the surface will depend on the depth of the biologically active soil layer, but on average this seal extends down to at about 5’ below ground level. Additionally, an Apron of sealing materials is added to surround the well shaft at ground level. This should extend at least 3’ from the casing and be incorporated into / consolidated with the grout of the Annular Seal. While working from the bottom of the Well Shaft to the top a point will be reached when the biologically active region of soil near the surface is exposed on the earthen wall. It is about a foot below this layer of soil where the shaft wall needs to be widened out to create an Annular Space of at least 1’ between the earthen wall and the casing to make the Annular Seal. The earth surrounding the Well Shaft is also excavated at a depth of about 9” – 12” and at least 3’ from the casing to form the Apron. Notice that there is a Curb formed into the outer edge of the Apron to prevent water from flowing up under the Apron. The Apron is filled in with the grout mixture at the same time as the Annular Seal area to make a consolidated casting.

The sealing of the Well Shaft with an Annular Seal in this manner eliminates nearly all of the potential for contamination from seepage from water sources in the soil. Also notice that the well’s Stand Up is sufficiently high to protect against ambient surface runoff water. The height of the Stand Up in addition to a properly constructed Apron Cap of flagstone or tile is particularly important in areas where monsoon rainfall creates the potential for flooding and regular ambient runoff water. A Stand Up height of at least 3’ is recommended in most areas of the Kalahandi District uplands. The other main preventable source of potential contamination of the well is the introduction of unwanted materials such as airborne bacteria, organic vegetation – mold, mildew, & fungi – and animal waste directly through the open shaft. For the most part this problem is solved by keeping a secure cover over the well opening. And once again, having a sufficient Stand Up height will help protect against these sources of contamination.

Biologically

Active

Soil

Sand and

Gravel Layer

Flagstone Cap

Covers the Bentonite / Cement Grout

Apron. This should be slightly sloped to

the outside to flash water away from the

Well Shaft.

Figure 3

Curb

Campus Development Series: Book One 9 Unfortunately, it is not possible to protect against ground water in the aquifer that already contains various chemical contaminants such as high nitrogen and phosphorous levels and metals like aluminum, iron, lead, and arsenic. Water treatment processes are required in order to correct these problems. However, the reason for constructing this primary Hand Dug Well is to provide water for construction purposes, and it is not intended to be a source of potable water at the onset. Therefore, it is not necessary to include any filtration and purification / processing systems into the initial design of the well.

STRUCTURAL CONCERNS: There are two main areas of concern regarding the structural integrity of a Hand Dug Well. Obviously, the materials and techniques as well as the actual design of the well constitute one area of concern. Secondly, and of equal importance, is the geology of the area where the well is located. It is at first important to know about the availability of ground water before planning the construction of a well. Is there an aquifer present that will sustain the desired yield of the well? Is this aquifer obtainable at a depth that is suitable for a hand dug well? And what is the quality of the water in the aquifer? Fortunately, in Kalahandi District there is an abundance of ground water. Statistically, most of the aquifers in the upland to lowland areas produce water at an average depth no greater than 26 feet during the driest months. So a good estimation of the total depth of a well in this region would be around 30 feet in order to provide a

consistent supply of water throughout the year.[4]

Note that after the aquifers are replenished during the monsoon months water tables rise to as shallow as 10 feet. Therefore, wells should be dug, optimally, during the month of June in order to reach the projected depth to provide adequate water during the dry months. Similar statistics should be obtained for other areas where well construction and other construction involving excavations and foundations will be done.

Dug Well Locations

Jan Feb Mar April May Jun Jul Aug Sept Oct Nov Dec Average

Upland 4.16 4.80 6.40 7.12 7.64 8.10 7.48 6.50 3.70 2.93 3.40 3.80 5.50

Medium Land

3.54 4.70 6.10 6.21 7.48 8.05 7.27 5.95 4.95 2.63 3.00 3.50 5.28

Lowlands 3.98 4.63 5.60 6.29 7.3 7.90 7.20 5.62 2.60 3.43 3.70 3.80 5.17

Monthly Averages

3.89 4.71 6.03 6.54 7.47 8.16 7.31 6.02 3.75 2.99 3.36 3.70 5.32

Source – District Collectorate Bhawanipatna (Table No. 4.2 from “Chapter – IV: Drought and Agricultural Productivity”)

The unfortunate circumstance is that most of the aquifers in Kalahandi District from which bore wells and hand dug wells obtain water contain unacceptable levels of chemical contamination for human and

livestock consumption.[5]

Therefore, treatment is necessary to produce potable water from these sources. But within limits the chemical contaminants will not affect the mixing and long term performance of the masonry materials used in the construction process.

4 “Chapter – IV: Drought and Agricultural Productivity,”

Via, http://shodhganga.inflibnet.ac.in/bitstream/10603/18473/14/14_chapter%204.pdf. (Accessed November 22, 2014)

5 Uma Shankar Kar, “Kalahandis, “New Crisis- Chemical Laced Water,” (Bhawanipatna: The New Indian Express, 09th May 2014 09:17 AM, Last Updated: 09th May 2014 09:58 AM,) Via, http://www.newindianexpress.com/states/odisha/Kalahandis-New-Crisis-Chemical-Laced-Water/2014/05/09/article2214688.ece (Accessed March 31, 2015)

Table 1 – Water Table Levels in Kalahandi District. (Average Depth of Open Well Measured In Meters)

Campus Development Series: Book One 10 A second geological concern is the type of ground into which the well will be dug. Because the well will be excavated by hand with a person actually working inside the shaft during construction, it is essential that the ground is suitable for digging without any risk of collapse. Naturally, this work should be restricted to types of ground composed of clays, sands, gravels and mixed soils where only small stones are encountered. The presence of large boulders or layers of flagstone will severely inhibit the excavation work using hand methods. Statistics based on extensive surveys in the area where the Vision Bible College Campus will be located indicate that the ground down to the desired well depth is indeed composed of clays, sands, and gravels mixed with hard compacted soils, so excavation there should

present no major problems.[6]

However, in any conditions it is advisable to provide a form of support for the walls of the shaft as the depth of the excavation increases. The photo in Figure 4 at the right shows a method of lowering vertical boards supported by

horizontal rings into the shaft as its depth increases.[7]

This technique and also an alternate method that can be used in less stable soil conditions will be discussed farther on. Adhering strictly to the materials specification given in the remaining discussion and following the specified construction techniques will also help ensure the overall structural integrity of the well as it is being constructed and when it is completed: keeping in mind that the objective is to build a structure that provides good service for many years into the future.

EXCAVATION METHODS: Step One – Consecration: Those who are constructing wells according to these plans will understand that the very first step of procedure once the proper location for excavation is determined is to consecrate the ground by sincere and fervent prayer. Pray for the workmanship and strength of the laborers. Pray for safety as work progresses. Pray for God’s favor to bring in a harvest of good water as the fruit of this labor. Meditate on God’s promise regarding the labor of our hands: (Deuteronomy 30:9-10) 9

“The LORD your

God will make you abound in all the work of your hand, in the fruit of your body, in the increase of your

livestock, and in the produce of your land for good. For the LORD will again rejoice over you for good as He

rejoiced over your fathers, 10

if you obey the voice of the LORD your God, to keep His commandments and

His statutes which are written in this Book of the Law, and if you turn to the LORD your God with all your

heart and with all your soul.” And where there is a need for insight, then ask God: (James 1:4-5) 5“If any of

you lacks wisdom, let him ask of God, who gives to all liberally and without reproach, and it will be given to

him.”

6 “Feasibility Study and Detailed Report for Phase-I Roads – Final Detail Engineering Report – Bhawanipatna – Khariar,”

(Bhubaneshwar, Orissa: Government of Orissa Works Department – Orissa State Road Project, Consulting Engineers Group Ltd., May 2007,)

Via, http://www.osrp.gov.in/writereaddata/Engineering/P01/Main%20Report-Bhawanipatna-Khairar.pdf. (Accessed September 27, 2014)

7 WaterAid, “Technical Brief – Hand-Dug Wells,” (WaterAid – Media – Publications Website),

Via, http://www.google.com/url?url=http://www.wateraid.org/~/media/Publications/Hand-dug-

wells.pdf&rct=j&frm=1&q=&esrc=s&sa=U&ei=VdAgVeKmFoLlsAWNvYG4Bg&ved=0CBQQFjAA&usg=AFQjCNHVyfaTnyrfz_-

oYnVn9L6e1gA1MA. (Accessed November 14, 2014)

Figure 4 Via: WaterAid / Jim Holmes

Campus Development Series: Book One 11 Step Two – Laying Out and Preparing the Work Area: As mentioned earlier, the diameter of the Well Shaft must be at least 4’ in order that there is adequate space for working with the presence of tools and materials inside the shaft. Even this will be a tight space, but any significant increase of the size of the shaft will also result in a significant increase in the volume of masonry and other reinforcing materials used to construct the casing and other features: and this also translates into significant increases of cost as well as working time. Therefore, the first task is to mark out this circular place on the ground: either inscribe the circumference with a stick, or if necessary mark it out with spray paint. Once this circumference is defined with a shallow trench dug by shovel, then the area of excavation is fairly well set. An essential feature of the excavation operation that will need to be constructed before or soon after the digging begins is a scaffolding arrangement above the shaft to serve as a suspension for a block-and-tackle used to raise excavated earth from the shaft and also lower materials and batches of masonry back down. Perhaps the simplest method of doing this is to lash together two tripods to suspend a horizontal beam at about 8’ above the ground. This allows adequate vertical space for the addition of the shaft support boards as shown in Figure 4 above.

Load Lifting: Because the quantities of earth and masonry to be moved out of and into the shaft will have a significant weight per load, it is advisable to use a block and tackle with a three to one mechanical advantage ratio. Notice that the block and tackle is suspended off to the side of center – nearer to the edge. When the load is lifted it is still hanging within the opening of the shaft, so it is necessary to place a board at least 2” thick under the basket then lower the load back onto this. The basket can then be slid over onto solid ground where its contents can be emptied into a wheelbarrow for removal. The main reason the lifting apparatus is suspended off to the side is to allow for a plumb-line to be suspended at the center of the circumference. This creates a datum point from which to measure the radius of the shaft as the depth increases, thereby ensuring that the shaft wall remains plumb.

Figure 5

Fixed

Block

Movable

Block

The rope is fixed to the movable block with

three freely rolling pullies to create a

mechanical advantage of 3:1

Figure 6

Campus Development Series: Book One 12 Digging a well must be a team effort. There should be no less than two individuals at the worksite at any time and preferably three or four. There must also be an appropriate compliment of safety equipment and First Aid provisions on hand. This work will be done in a remote location with possibly limited access and transportation to a medical facility, so at least one person working on site must have very good First Aid training. Some items to have available will be;

► The First Aid Kit, containing alcohol, iodine, antibiotic ointment, small and large bandages, gauze, adhesive tape, a tourniquet, and materials to make a splint, etc.

► A sufficient supply of fresh, potable water.

► A compost toilet.

► A shaded area / canopy for rest out of the direct sunlight. Step Three – Start Digging: Digging the shaft above the Aquifer Zone will be relatively routine since the soil down to this depth should be dry and solidly packed. It is when the digging reaches the depth of the Aquifer Zone that the soil may become damp and more subject to mudslide and collapse. According to statistics given above, the Aquifer Zone may be reached at a depth as shallow as 10’ in many parts of the Kalahandi District uplands. Of course, during the driest month of June when the digging will be done the Water Table will not be reached above a depth of at least 20’, and hopefully more at 25’. Never-the-less, the soil conditions within the entire Aquifer Zone will likely be much softer and more porous than above this Zone, so special care should be taken to support the shaft wall once the excavation reaches this Zone. If it is detected at this point that the soil in the Aquifer Zone is not solid and is subject to collapse, then it will be necessary to use an alternate method of excavation and installing the Well Casing. This is to say that it will not be safe to continue the excavation to a depth of 30’ using the boards to support the walls, and then place the Ferrocement casing In-Situ from the bottom to the top with the waterproofing Bentonite / Cement Grout in the Annular Space as discussed earlier. However, assuming that the shaft wall is solid enough to safely dig to the desired 30’ depth, this technique of In-Situ Ferrocement placement will be given first. The alternate method will be shown as the back-up plan.

Wide Shovel for

Digging And

Removing Soil

Sharp Narrow Shovel For

Deep Cutting and Defining Edges

Hand Maddox for Trimming

Shaft Wall to Proper Radius

Heavy Steel

Tamping Rod

with Sharp Point

at One End and

Prying End for

Breaking and

Moving Large

Stones

Pick Adz for Breaking Soil Figure 7

Campus Development Series: Book One 13 Start the excavation by using the sharp narrow shovel to cut down around the circumference. This will form a relatively deep trench that defines the circumference of the shaft. The interior of this area will be removed with the wide shovel, working to keep a relatively level floor inside the excavation. This dirt can be easily removed and placed on the ground outside the excavation until the hole becomes about waist deep. After this it will be necessary to use the block and tackle with the basket to remove the soil from the work area. Note that with a well shaft diameter of 4’ there will be about 63 cubic feet of earth removed for every 5’ of depth. This will add up to about 380 cubic feet when the full depth of the well is excavated, so it is necessary that this material is removed to a comfortable distance from the work area by wheelbarrow as it is excavated from the shaft. The person doing this work will necessarily need to have a wide shovel in addition to the person working inside the shaft. Also, as this material is removed it should be set aside in different areas for different types of soil. For example, keep the biologically active top soil separate from lower sand and gravel materials and likewise separate clay materials into another area. This will facilitate the re-use of these materials for different types of back-filling and landscaping later on.

It is desirable that the shaft wall is kept plumb from top to bottom and also that it is cut as smoothly as possible to keep a uniform circumference. Because volumes change proportionally by factors of the dimensions cubed, irregularities in the shape of the wall will dramatically affect the volume of materials – mainly the Bentonite / Cement Grout – needed to finish the well casing. If the wall is trimmed smoothly at a uniform radius of 2’ from the plumb line using the Hand Maddox as in Figure 9, a reasonably accurate calculation of the amount of Bentonite / Cement Slurry needed to fill the Annular Space will be possible. Also, consider that the outside circumference of the Ferrocement casing is measured from the earthen wall at 1 ½” using the Slip Form.

The Basket should be large enough to lift about a half

wheelbarrow load of dirt at a time from the excavation

but not so large that it obstructs work while it is lowered

into the shaft. Also consider that the weight of each load

should be limited to not more than 150 lbs, which will

require 50 lbs of lift with the 3:1 mechanical advantage.

The Basket is suspended from each corner by lines that

are securely fastened to a ring to provide a central point

of lift. This prevents the basket from undesirable tipping

while it is in use.

Point of Lift by

Block and Tackle

Figure 8

2’ Radius

Measured

From Plumb

Line

Figure 9

Campus Development Series: Book One 14 The preferred method of digging within the shaft is to hollow out the center area first with a shovel to a depth of 1’ below the area at the edge near the Shaft Wall. Then work at the outer edge with the Hand Maddox. This will provide a space downhill from the work area to remove soil to as the detailing of the radius is done. Hopefully, working in this manner the excavation work will progress safely at a rate of around 10’ of depth per day so that it will only take three or maybe four days to complete the digging and prepare for the placement of gravel to create the Intake Chamber and begin the In-Situ Ferrocement work to form the casing. Step Four – Install the Wall Support System: The boards to support the Shaft Wall will need to be installed when the excavation reaches a depth of about 6’, and this Support System will need to be re-positioned as the depth increases in stages of about 2’ - 3’, depending on how stable the soil is at lower depths. Of course, this adds time to the excavation work, but if the Support System is designed properly this added time will not be excessive. However, it is essential that the Support System is manufactured and all of its components are present at the work site prior to beginning the excavation. The photo in Figure 4 on page 8 shows that the vertical boards are supported with horizontal, steel rings that have an outside diameter about 4” smaller than the diameter at the inside face of the boards. This allows pressure to be applied against each individual board around the circumference with wedges that can be loosened and tightened to allow for the re-positioning (slipping up and down) of the boards individually. Chances are that rings of this sort and at the desired size for this purpose are not readily available without hiring a professional well digging crew / company; although it is possible that they can be rented if there is such a company nearby. Otherwise, it should be expected that these will need to be manufactured either on site or at another location and transported to the site.

Although the well construction will take place at a relatively remote & undeveloped site, it is assumed that there will be access to some place where electricity is available and power tools can be used – either in a nearby village or by locating an electric power generator on site, which will need to be done in any case. Primarily, an electric jig saw should be used to cut the rings and arc sections, and a power drill should be used to drive the screws to fasten the laminations together.

A single 4’ X 8’ sheet of

¾” plywood will render

two full rings at 38”

outside diameter that are

2 ½” wide. By carefully

plotting arc sections on

the remaining wood there

will be enough pieces to

construct two Support

Rings that are 3” thick

(four ¾” layers) from

each plywood sheet.

The inside diameter of

the rings will be 33”

Pressure applied against the vertical boards

with wedges that are about 1 ½” thick.

The ring is constructed by laminating four ¾”

layers to build up to a 3” thickness. Begin with

a solid ring at the bottom and attach the

remaining arc sections with glue and screws.

Stagger the arc section joints to create a good

overlap.

Figure 10a

Figure 10b

Campus Development Series: Book One 15 To dig a well of 30’ it will be necessary to have enough Support Rings such that they can be spaced at intervals of no more than 3’, which would be a minimum of 10 rings. For the sake of safety it would be good to construct 12 rings while the tooling and manufacturing process is organized. This will require a total of six 4’ X 8’ sheets of ¾” plywood. Additionally, in order to conform easily to the Shaft Wall circumference, the vertical boards should be no wider than 6” each. Considering that the circumference at 1” inside the wall is 146”, then it will require twenty-four boards to go all the way around the wall. These 6” wide boards can also be cut from full 4’ X 8’ sheet of ¾” plywood, and there will be eight separate boards at 8’ long / sheet. So it will take three full sheets to cut the twenty-four boards to line the Shaft Wall. For a shaft that is 30’ deep the 8’ vertical boards will need to be stacked four high (32’) to provide full support. Therefore, a total of twelve 4’ X 8’ sheets of ¾” plywood will be needed to cut all of the vertical boards (total of fifty-six) for the Support System. And this brings the total number of plywood sheets that need to be purchased to manufacture the Support System to eighteen. The total number of wedges at 6” long X 1 ½” X 1 ½” that need to be available will be at least [24 per ring X 12 rings = 288]. These can be cut from 2” X 4” X 8’ framing studs with a power circular saw by first splitting the stud in its length and then cutting the resulting 1 ½” X 1 ½” poles to 6” lengths. The ends of the individual pieces can be trimmed with a hand axe to shape them into the desired wedge shape. Each 8’ stud will render thirty-two wedges, so a total of nine studs will be needed to cut the required quantity of wedges. There are significant amounts of time and materials required to manufacture the components of this Shaft Wall Support System. This is a tool system that can be used for many other similar Hand Dug Well projects if the care is taken to ensure good quality workmanship at the onset. It is desirable to apply some form of waterproofing to the individual components – especially the Support Rings – in order to extend the life of the system. This could be a commercial grade sealer like Thompson’s Water Seal™ used to waterproof wooden decks, a homespun paraffin based sealing agent, or a urethane spar varnish, depending on what is easily available locally. To Summarize Materials & Tools Needed to Construct Shaft Wall Support System:

► 18 ea. 4’ X 8’ Sheets of ¾” Plywood.

► 9 ea. 2” X 4” X 8’ Framing Studs.

► 1 Gallon of Good Carpenter’s Wood Glue, Or if possible to obtain use Gorilla Glue™.

► 15 lbs #8 X 1 ¼” Wood (Sheetrock) Screws.

► Sufficient Quantity of Waterproofing Agent.

Circular

Saw

Power Drill

Screw Gun

Power

Jig Saw

Figure 11

Campus Development Series: Book One 16

Installation:

Figure 12 above shows that when the first course of Vertical Boards is installed their tops will extend above the top of the shaft opening by about 2’. With a full set of boards held tightly in place with the pressure of the wedges against the Shaft Wall the tops should be solid enough to place the 2” thick board across them at the edge in order to set the basket on it and slide the load out of the opening for unloading into the wheelbarrow. After the first re-positioning of the Vertical Boards their tops will be below ground level, so the 2” board will sit on solid ground again after this point. The Vertical Boards are re-positioned when the excavation reaches an additional depth of 3’ below the bottoms of the boards. This re-positioning is done by loosening each of the wedges for an individual board so that it slides freely up and down. Note that the wedges do not need to be removed completely, just tapped up so that they are loose. Next, allow the board to slide down to the new bottom of the excavation and retighten

its wedges. Repeat this procedure for each of the boards so that they are all resting at the bottom of the excavation. Once this is done the rings also have to be re-positioned. Do this by loosening all of the wedges around the bottom ring, then reset it at about 6” – 8” from the bottom of the boards. Do this again to reset the rings above at their respective 3’, 6’, . . . positions above the bottom.

Begin by placing two

Vertical Boards on

opposite sides of the

shaft. Set the bottom

ring first at about 6”

– 8” from the bottom

of the boards. Next,

place two more rings

at 3’ and 6’ from the

bottom of the boards.

Top View of the ring

centered and supported

on four sides with

wedges applying

pressure on the first

four Vertical Boards.

Continue by placing two more boards

offset by 90 degrees from the first two.

Figure 12

Once the first four boards are installed and the three rings are

centered and supported, then the remaining 20 boards and wedges

can be installed to complete the solid wall support system.

When the repositioning of the first course of Vertical Boards

lowers their tops down to a depth of 6’ below ground level, then the

second course can be installed. This is done in the same manner as the

first course, except that the bottom ring will be placed to overlap the joint

between the lower and upper boards. Otherwise, the rings will be placed

at spacings of 3’ and 6’ above this joint.

Figure 13

Campus Development Series: Book One 17

Critical Points: As mentioned earlier, the digging and re-positioning of the support system should be routine in the upper part of the shaft where the soil is dry and solidly packed. However, there are two Critical Points that will be reached as the excavation depth increases where it must be determined if the soil is firm enough to continue working in the manner shown above. The first Critical Point will occur at the depth where the Aquifer Zone is encountered, and the second will be at the actual Water Table. The Aquifer Zone presents a case for special consideration – different from the soil above – because it is subject to complete saturation by water on an annual / cyclic basis, and this has certainly been the case for some centuries at the least. Therefore, it is not characteristic of most aquifers / aquifer zones to contain large quantities of clay and other solids that tend to compact tightly. Aquifer zones do contain a lot of sand, gravel, and large stones through which water can flow easily, but for the most part the binding agents and organic matter found in upper layers of soil have long since been washed away or were never present at the depth of the aquifer. So when a shaft is dug into this soil composition there may be a tendency for this particulate aggregate to shift and slide to fill the void, even if there is not water present above the actual Water Table. Of course, it will be necessary to dig down a least a few and probably several feet into this zone to determine exactly what its characteristics are and how stable it will be under excavation. This should be done by digging out a smaller area no more than 2’ in diameter at the center of the shaft, thereby leaving the soil at the edges undisturbed. Hopefully, the region of the Aquifer Zone above the Water Table will be relatively solid – much like soft sandstone – so that excavation can progress down to the level of the Water Table without a worry that the Shaft Wall will collapse. Although the Shaft Wall Support System will protect against a catastrophic accident if the soil gives way while digging, it will eventually be necessary to extract this protection by up to 4’ at a time so that the work of placing the casing can be done. If at this point where the excavation enters the Aquifer Zone, or at any level below this, it is determined that the soil is not stable enough to continue digging down to the water table and then install the casing as desired, then the excavation must stop immediately and the alternate method of installing the casing / excavation below this point must be employed. However, in the case that the soil is stable, then continue the excavation as before until the Water Table is reached. Again, according to the statistics given in Table 1 on page 6 the active Aquifer Zone should be reached at a depth of around 10’ in the uplands of Kalahandi District. During the wet seasonal monsoon months (August – early November) the water in the aquifer will rise up to this level. However, by the end of the one year period before the rains begin, June being the driest month, this water level will drop to an average depth of around 20’ – 25’. It is at this lower depth where the actual placement of Ferrocement to form the casing will begin. But, the well must be dug to an additional depth of at least 5’ below the Water Table in order to create an Intake Chamber and allow for water to be drawn from the aquifer. Step Five – Working Below the Water Table: It is at the Water Table that the excavation technique will change. Of course, the soil below the Water Table will be saturated with water, so it may tend to be fluid like mud. Also, the water will tend to maintain a level at the top of Water Table regardless of how much soil is removed below this level. So, for one, it will be necessary to pump the water out of the bottom of the shaft when digging below the Water Table begins. And secondly, it will be necessary to lower the Shaft Wall Support System at nearly the same rate as the digging is done in order to prevent the fluid soil from collapsing.

Campus Development Series: Book One 18

Pumping the Water Out: It is desirable that the well has a good yield and recovery rate when it is in use, but this can present a problem when the excavation work is in progress. The higher the recovery rate, the faster the water has to be pumped out of the Intake Chamber to keep this space dry while digging. There will need to be at least one good submersible pump (sump) and possibly two on site in order to keep up with this recovery rate. Using the sump, which is electrical, will also require that there is a power source available. This power source will most likely be a portable generator. The water that is pumped out of the well below the Water Table while completing the Intake Chamber will be used to start mixing the concrete for the casing

and also the Bentonite / Cement Grout, so there needs to be some provision to contain it as it is pumped out. One method of doing this is to dig a small pit nearby the work area and line this with a plastic / visqueen membrane so that it can be used as a holding pond. This pond should have a capacity of at least 100 gallons. Another method of collecting this water is to have two 55 gallon barrels on site. Both methods are sufficient to hold enough water to mix the concrete. Note that the well will continue to produce water once the pump is set in the Intake Chamber, so the supply of reserve water will be replenished continually as the Ferrocement and grout work progresses to higher levels.

Step Six – Prepare the Intake Chamber: When the excavation has reached a depth of at least 5’ below the Water Table it is time to prepare the Intake Chamber. Start by filling the bottom with medium sized, firmly compacted gravel. Work in layers of 6’ at a time, lifting the Vertical Boards only enough to solidly pack the gravel around the edge of the shaft with each layer until a depth of not less than 3’ has been reached. Be certain that for a width of around 1’ around the perimeter the gravel is level all the way around the shaft; if necessary use smaller gravel and finely crushed chert at the upper 3” – 6” to ensure that a compacted level surface is obtained. Next, stack up rings of 8” X 8” concrete blocks to a height of at least 6” above the Water Table. Offset the joints by ½ block for each course, and fill the insides of the blocks with a dry

Keep the center

of the shaft dug

out at least 2’

below the

working surface

so that the

sump will drain

water out of the

way of the

work.

Loosen the wedges

on 3 or 4 adjacent

Vertical Boards at a

time and allow them

to slide down as the

edge of the shaft is

trenched out. Work

this trench all the

way around before

removing the

remaining soil in the

shaft.

Figure 14

Compacted medium

sized gravel at a depth

of at least 3’ to allow

intake from the aquifer.

The well casing is placed

directly on top of a wall of 8”

X 8” concrete blocks.

Figure 15

Campus Development Series: Book One 19 compacted mix of chert and Portland Cement. Do not lift the Vertical Boards of the support system higher than is necessary to install each course. With the blocks placed tightly together in each course they will act on their own as a retaining wall to prevent the collapse of the soil around them. Otherwise, the support system must be kept in place while working below the Water Table. Note that the sump must be kept pumping at a level at least 6” below the top of the compacted gravel in order to keep the Intake Chamber above this level emptied of water while placing the concrete blocks. It would also be preferable to keep the sump working until the first 3’ of casing is placed above the concrete block level. This will allow work to be done while standing on the dry gravel until it becomes necessary to set up a boson’s seat for working at higher levels. Step Seven – Placing the Ferrocement Casing and Bentonite / Cement Grout: Prior to this point while working below the Water Table the Vertical Boards of the Shaft Wall Support System have been lifted up only by 6” – 8” increments as the medium sized gravel and the concrete blocks are placed. However, in order to install the reinforcement wire & rebar and use the Slip Form to cast the casing it will be necessary to lift up the support system in increments of 3’ – 4’ at a time. Of course, the placement of the casing will start by raising the support system up to at least 3’ above the top of the concrete block wall. Since a concrete block wall with filled chambers is used as the foundation for the casing rather than placing it directly on the compacted gravel as shown in Figure 2b on page 4, it will not be necessary to put down a waterproof barrier to prevent the Ferrocement and Bentonite / Cement Grout from slumping into the gravel. However, it is necessary to be certain that the space between the shaft wall and the concrete blocks is solidly filled with soil to keep the grout slurry from flowing down into it. Begin by setting the Slip Form in place on top of the block wall with the spacers against the shaft wall so that it will be behind the reinforcement Armature when it is installed. Because all of the iron in the Armature has to be encased inside the concrete in order to prevent exposure to moisture and other elements that will cause rust and corrosion it will also be necessary to construct the Armature up off the brick wall by about 1 ½” all the way around the circumference. Do this by setting unused wedges on top of the bricks at about one foot apart. Position these so that they can be easily pulled out as the concrete is worked around them. Next, install the Armature up to a height of 2’ by first placing a ring of hardware cloth around the circumference. The casing will be 3” thick, so the first layer of hardware cloth should be inset from the outer circumference by around 1”. Attach vertical 2’-6” lengths of 3/8” (#3) rebar at 2’ intervals around the circumference by using bailing wire to fasten them to the hardware cloth; (this will be six pieces of rebar). There will be three rings of horizontal rebar attached with wire to the vertical rebar pieces at 2” from the bottom, in the center of the 2’ section, and at 2” from the top. These are bent to conform to the circumference just inside the direct center of the casing, which will be a radius of about 20 ½”. Because the inside diameter of the support system rings will not allow for these to be lowered into the shaft in one piece they are prepared as 3 arc sections per ring that extend 8” beyond 1/3 of the circumference. Cut these pieces to 51” lengths to provide a 4” overlap at the joints of the 3 pieces that can be wired together when they are in place. To complete the section of armature place a second ring of hardware cloth around the inner circumference of the three horizontal rings. This 2’ high section of reinforcement Armature will be a relatively solid structure that stands directly in the center of the 3” thickness of the casing. When the Armature is all tightly bound together like this with the bailing wire the wooden wedges can be removed and replaced with stones that will hold it up to the desired height above the brick wall and which will consolidate within the concrete of the casing.

Campus Development Series: Book One 20

Mixing the Concrete / Mortar: The ingredients needed to mix the mortar are Portland cement (available in 94 lb sacks), medium grit sand, and water. Typically, the mixture used for ferrocement well casings and water storage tanks is prepared at a ratio of between 3 parts sand to 1 part Portland cement (3 : 1) and 2 parts sand to 1 part Portland cement (2 : 1). For beginners who are not very familiar with the properties and performance characteristics of masonry products it might be best to select a ratio in the middle – which is 2.5 parts sand and 1 part Portland (2.5 : 1). This combination can be mixed in large quantities and set aside for mixing with water to make up small batches to send down into the shaft in the basket. For example, make up a full 94 lb bag of Portland with 235 lbs of sand for the proper mix ratio. Note that dry sand has a weight of about 103.7 lbs per cubic foot, so it will take about 2.3 cu ft of sand per bag of Portland to make the proper mix ratio. There are 7.48 gallons per cu ft, so if 5 gallon buckets are used to measure the quantity there will be 1.49 buckets full per cubic foot, and 3.44 buckets full of sand will be needed per 94 lb bag of Portland cement for a mix ratio of (2.5 : 1).

First / Outer Layer

of Hardware Cloth

Vertical 3/8” (#3) Rebar

attached to the inside of

the Outer Layer

Horizontal Rebar Rings

attached to the inside of

the Vertical Rebar

The Inside Layer of Hardware Cloth attaches to the

inside of the Horizontal Rings so that the total

thickness of the Armature from outside to inside is

just at 1”

The Vertical Rebar pieces

are cut at 2’-6” long to

provide an extra length

above the 2’ height of the

Hardware Cloth for

attaching the next course of

Vertical Rebar with bailing

wire.

Likewise, the three Arc

Sections of the

Horizontal Rings are

bound together with

two tight wraps of

bailing wire at each

overlapping joint.

Figure 16

Campus Development Series: Book One 21 The mortar must be the consistency of a thick past, as stiff as possible, when mixed with water so that it will stand in place when it is formed up to 2’ high with a trowel as it is placed around the circumference in each course. This will be a Slump of about 2”, as noted on page 5. In order to make a mortar of this consistency, a mix ratio of water to Portland / sand mix should be about 0.4 parts water to 1 part dry mix (0.4 : 1) by weight. Water has a weight of 62.428 lb / cu ft. The dry Portland / sand mix will have an average weight of 116 lbs / cu ft. The ratio indicates that there will be 4/10 as much water as there is Portland / sand mix by weight in each mixed batch of mortar. Therefore, [116 lbs of dry mix X 0.4 = 46.4 lbs of water]. This 46.4 lbs of water is about 0.74 cu ft. Since there are 7.48 gallons per cu ft, then [0.74 cu ft X 7.48 gallons / cu ft = 5.559 gallons]. So there will be 5 ½ gallons of water added to each cubic foot of dry mix to make the mortar with a proper slump / stiffness. This ratio of water to dry mix is confirmed at

each of the sites researched.[8] The consistency of the mortar can be adjusted to be stiffer by adding dry

Portland / sand mix or softer by adding water once this initial ratio is thoroughly mixed and tested. Important Technical Note: The curing / setting up of concrete & mortar is a process called “slaking” whereby the water in the fluid mixture chemically bonds with the lime in the Portland cement and carbon

dioxide in the air to form the solid concrete substance.[9]

Therefore, the water does not evaporate away from the cement as in the hardening of clay / mud and ceramic applications. So the quantity of water used remains as a component of the overall volume and weight of the solid structure. The ratio of water / dry mix is determined by weight, not volume. In the case of this mortar mixture,

the weight of the water will constitute 4/10 of the overall weight of the concrete of the casing. However, in

order to determine how much water in gallons will need to be available to mix the mortar for the casing it

must be known what the mix ratio is by volume. Because the Portland / sand mix is denser per volume than

water @ 116 lbs / cu ft for the dry mix verses 62.428 lbs / cu ft for water, then the mixture ratio by volume

becomes 0.538 parts water to 1 part dry mix ( 0.538 : 1 ) rather than ( 0.4 : 1 ) by weight. At a height of

about 25 feet from the concrete blocks (water table in the dry month of June) to the top of the well, the

volume of the 3” thick casing will be about 68.722 cu ft. Giving that the volume of the Armature iron work

will be about 1.1475 cu ft, then the volume of the mortar will be 67.575 cubic feet. But to make a quick

calculation: [67.575 cu ft of mortar X 0.538 = 36.355 cu ft of water]. [7.48 gallons / cu ft X 36.355 cu ft

= 271.94 gallons of water]. In other words, 5 ea. 55 gallon barrels of water will be sufficient to mix the

mortar. And there will be a need for an additional quantity of water to mix the Bentonite / cement grout

slurry, which will be calculated below.

The quantity of Portland / sand dry mix in the casing will be, [67.5748 cu ft mortar volume – 36.355 cu ft of water = 31.22 cu ft dry mix ]. The (3 : 1) means that ¼ of the dry mix will be Portland

8 Brian Skinner, Bob Reed , Rod Shaw , “36. Ferrocement Water Tanks,” Leicestershire: WEDC Loughborough University Leicestershire

LE11 3TU UK, www.lboro.ac.uk/departments/cv/wedc/ wedc@lboro.ac.uk, Via, http://www.lboro.ac.uk/well/resources/technical-briefs/36-

ferrocement-water-tanks.pdf. (Accessed April 20, 2015)

Curt Beckmann, Eric Blazek, “Original:Ferrocement Applications in Developing Countries 9,” Web Page last modified 12:09, 14 July

2011. Via, http://www.appropedia.org/Original:Ferrocement_Applications_in_Developing_Countries_9. (Accessed April 20, 2015)

Ferrocement.com webpage, via, http://www.ferrocement.com/casa-ca1/ch1.en-ferroHouse-web.html. (Accessed April 20, 2015)

9 Andrew Alden - Geology Expert, “ Cement and Concrete,” About Education Website,

http://geology.about.com/od/mineral_resources/a/cement.htm. (Accessed April 20, 2015)

Campus Development Series: Book One 22 cement. Therefore, [31.22 cu ft dry mix X 0.25 = 7.81 cu ft Portland cement]. Since there is one 94 lb bag of Portland / cu ft, then there will need to be 8 bags of Portland present to make up the dry mix. Similarly, ¾ of the dry mix will be sand, so [31.22 cu ft dry mix X 0.75 = 23.42 cu ft of sand]. The sand may also be available in bagged quantities by weight, or it may be necessary to purchase this in bulk volume or by weight. Having a weight of about 103.7 lbs / cu ft, the total weight of sand needed will be 2,428.8 lbs or 1.25 ton.

Mixing the Bentonite / Cement Grout Slurry: As noted earlier on page 5, Sodium Bentonite Clay has the potential to expand to as much as 15 times its powdered form volume when mixed with water. Because of this, many professionals prefer to mix the Bentonite with water and allow it to expand to full volume for about 24 hours before adding Portland cement to make the grout slurry. This produces the highest level of impermeability of the grout but also reduces the volumetric stability of the grout. Proponents of this method contend that, “When using cement / bentonite grout, bentonite should be added to the water first, because if bentonite is added to a cement and water mix an

ion exchange takes place and the expansion of the bentonite is reduced significantly.”[10]

Mixing the water and Bentonite first and allowing for full expansion of the Bentonite renders the highest level of impermeability and also yields a higher volume of slurry per sack of Bentonite than mixing dry Bentonite to a premix of water and cement. On the other hand, when there is a strict concern for the compressive strength of the grout once it is set it is more desirable to mix the cement and water in proper proportions before adding the Bentonite. This ensures that a regulated slump of the cement mixture and consequently the strength and volume of the solid grout can be predicted. There are advantages and drawbacks to both methods, so the particular on-site conditions will be the

determining factors for which method to use. [11]

Note that most of the discussions of procedure and mixing

ratios for preparing Bentonite / cement grout pertain to applications where sensitive equipment is present in

the encased area or specific permeability requirements are desired to contain or hold out chemically hazardous

materials, so the recommendations therein are intended to meet strict regulatory specifications. The objective

here of sealing the Annular Space around the well casing is not so demanding. In this case, the main concerns

are that the grout will have a high level of impermeability and also that it is reasonably solid to reduce

plasticity and susceptibility to wash out of the Bentonite in the presence of flowing water. The second factor

to consider is that the Bentonite has reached a state of volumetric stability when the slurry is mixed so that it

10 M. Luan, C. Xu, Y. He, Y. Guo, Z. Zhaug, D. Jin, Q. Fan, “Experimental Study On Shear Behavior And An Improved Constitutive Model Of

Saturated Sand Under Complex Stress Condition,” Soft Soil Engineering: Proceeds of the Fourth International Conferences on Soft Soil Engineering,

Vancouver, Canada: David H. Chan, K. Tim Law, eds., Taylor & Francis Ltd, 28-Sep-2006, (pg. 99). Via,

https://books.google.com/books?id=_9mc9sz7XVgC&pg=PA446&lpg=PA446&dq=Soft+Soil+Engineering:+Proceedings+of+the+Fourth+Internatio

nal+Conference+on+...+edited+by+Dave+H.+Chan,+K.+Tim+Law&source=bl&ots=TjhwoVW-

ZC&sig=VoO8NK_2FHXpEfhDIAEzvREnynM&hl=en&sa=X&ei=Eyg2VYnCEM6zogSMhYHgDA&ved=0CCYQ6AEwAw#v=onepage&q=Soft%20Soil%20Engineering%3A%20Proceedings%20of%20the%20Fourth%20International%20Conference%20on%20...%20edited%20by%20Dave%

20H.%20Chan%2C%20K.%20Tim%20Law&f=false. (Accessed April 21, 2015)

11 P. Erik Mikkelsen, “Cement-Bentonite Grout Backfill for Borehole Instruments - Current Use of Bentonite Materials and Technology,”

GEOTECHNICAL INSTRUMENTATION NEWS website, Geotechnical News, December 2002,

Via, http://www.geosense.co.uk/media/BlockAttributeValueFile/129/file/CementBentonitegroutbackfillforboreholeinstruments.pdf

(Accessed April 20, 2015)

Campus Development Series: Book One 23 does not place excessive pressure against the casing, on the one hand, or tend to expand and overflow from the

Annular Space once the slurry is poured. The best method to obtain this consistent volume as well as the

desired permeability properties will be to mix the Bentonite and water together a day in advance, and then to

add the Portland at the time that the slurry is poured.

Table 2. Cement – Bentonite Grout Mixes (Adapted from DGSI Website)[12]

Application Grout Medium to Hard Soils Grout for Soft Soils

Materials Weight Ratio by

Weight

Weight Ratio by

Weight

Water 30 Gallons

250 lbs

2.5 75 Gallons

626 lbs

6.6

Portland

Cement

94 lbs 1 94 lbs 1

Bentonite 25 lbs 0.3 39 lbs 0.4

Since there is not a regulatory specification to meet in the case of sealing the Annular Space of this well, the mix ratio for Medium to Hard Soils is preferred because the quantities of water and Bentonite will be less than the ratio for the Soft Soil mixture. Due to the expansive properties of Bentonite these quantities will not be exact. However, the ratio given in Table 2 provides a means of estimating how much material to purchase and have available on site. The other factor needed to make this estimate is the sum of the volumes of the Annular Space, Annular Seal, and Apron that will be filled with the grout. The volume of the 1 ½” Annular Space from the concrete blocks up to the level where the Annular Seal begins (about 20’) is around 30.5 cu ft. The volume of the Annular Seal, which is about 4.5’ deep with a 6’ diameter, is around 77.53 cu ft. And the volume of the Apron that is an additional 3’ diameter from the outside of the casing and a depth of 10” below ground level will be around 56.25 cu ft. The total volume of Bentonite / Cement Grout will be around 164.28 cu ft. The 94 lb bag of Portland Cement has a volume of 1 cu ft. 30 gallons (250 lb) of water has a volume of 4 cu ft. Sodium Bentonite (dry) has a weight / volume ration of about 69 lbs / cu ft. Bentonite generally is available in 50 lb bags, which will have a dry volume of 0.7246 cu ft. And 25 lbs of Bentonite has a volume of 0.3623 cu ft. With all of the ingredients mixed together in the given ratio (as per 1 ea. p4 lb bag of Portland) the slurry batch will have a total volume of [1 cu ft Portland + 4 cu ft water + 0.3623 cu ft Bentonite = 5.3623 cu ft ]. The total volume of the Annular Space – Seal- Apron @ 164.28 cu ft divided by 5.3623 cu ft per batch of slurry = 30.63 batches of slurry (as per 94 lb bag of Portland) will be needed. Therefore, the estimated quantities of materials needed for the Bentonite / Cement Grout Slurry will be about; 31 bags of Portland: [30.63 / 2 = 15.32] to be 16 ea. 50 lb bags of Bentonite: [30.63 X 30 gal] to be 919 gallons of water. This is a good place to take note of the fact that the increased radius of the Annular Space and Annular Seal, which becomes a quantity squared X π in the calculation of the surface area of these features dramatically increases their volumes compared to the volume of the casing.

12 “Slope Indicator - Grout Mixes for Inclinometers,” DGSI Website, Durham Geo Enterprises, Incorporated, A Nova Metrix Company,

Via, http://www.slopeindicator.com/support/inclinometers/technote-groutmix-inclinometers.php. (Accessed April 20, 2015)

Campus Development Series: Book One 24

Placing the Mortar: Figure 17 shows what the beginning of the mortar placement on top of the concrete block wall will look like. Here it is seen that the wooden wedge used to hold the Armature up from the blocks is replaced with a stone that will consolidate with the mortar to be watertight and protect the iron of the Armature from exposure to elements. Next, with the Slip Form in place a quantity of mortar is “thrown” against the Armature near the block wall using a trowel so that it penetrates through the grid of the iron to form up solidly against the face of the Slip Form. Use a stick to work the mortar by poking so that it slumps into a solid, monolithic mass. Repeat this procedure of throwing the mortar through the Armature until a mass about 1’ high, 3” thick and as wide as the Slip Form has been placed. This will be about half the height of the Slip Form.

If such a tool is available, a modified orbital palm sander is used as a vibrating trowel to shake and

thoroughly consolidate this first volume of mortar and to smooth over its face.[13]

The primary modification of this tool is that its sanding pad has been replaced with a metal plate that works as a trowel face. It may also be necessary to work this face over to ensure that it forms up smoothly and at a uniform 3” from the face of the Slip Form. And of course, if the electric palm sander is not available, then it will be necessary to do all of this work of shaking and consolidating the mortar using a hand trowel. Note that it is a good practice to insert two thin strips of wood – about 1/8” thick – behind the wooden spacers of the Slip Form so that once the casing section is formed these can be removed to release the form to move freely within the Annular Space. Keeping the form loose in this manner will make it possible to easily move it to a next position once this first section of casing is formed. Once this first mass and section of casing is worked to satisfaction continue by throwing a second batch of mortar above this up to nearly the top of the Slip Form and also across its width. Repeat the procedure to consolidate this mass with the one below and form up the total casing section, which will be about 2’ high X 3’ wide. When this section is all worked and standing solidly without slumping, rotate the Slip Form to the next adjacent position and repeat this procedure to form up another section. Note that it is very important to consolidate all of the mortar at the working edges between the previous section and the newly thrown mortar so that a truly monolithic casing is formed. And this procedure is repeated all the way around the circumference until the first 2’ high course is completed. And this is a good place to emphasize that once the work of placing the mortar is begun it must continue until the casing is finished to the top, so there will need to be at least two crews available to alternate shifts as this work will probably take more than a single day to complete.

13 Curt Beckmann, Eric Blazek, “Original:Ferrocement Applications in Developing Countries 9,”

The Slip Form maintains the 1 ½” Annular Space

between the Ferrocement casing and the earthen Shaft

Wall.

Armature

8” X 8” Concrete Block

A 1 ½” diameter stone holds the Armature

up off the block wall to ensure complete

encasement of the iron within the mortar.

Modified Palm

Sander used to

consolidate the

Mortar.

Figure 17

Campus Development Series: Book One 25 At this time lift the Shaft Wall Support System up another 3’. Also, lift the Slip Form out of the Annular Space so that it is void and ready to receive the placement of Bentonite / Cement Grout Slurry. As noted earlier, the volume of the 1 ½” Annular Space from the concrete blocks up to the level where the Annular Seal begins (about 20’) is around 30.5 cu ft. Therefore, the volume of this space for each 2’ course will be around 3 cu ft, and this is how much of the slurry should be mixed at a time to pour into this newly formed space. In order to be prepared to mix the slurry in small batches, it is necessary to have a conversion factor on hand in order to calculate the relative proportions of the ingredients. So, because the total volume of Bentonite / Cement Grout to complete the entire Annular Space and & Seal with Apron will be around 164.28 cu ft, and the volume per course is 3 cu ft, the conversion factor will be [3 cu ft / 164.28 cu ft = 0.01826]. By multiplying this factor by the quantities of ingredients for the total volume of slurry, the amounts needed to mix batches for a single course can be found. The actual proportions of the ingredients will be; 14 lb Bentonite (1/3 of a 50 lb bag): 17 gallons of water: and .5698 bag of Portland. Recall that the Bentonite and water will be mixed together in advance to allow time for the Bentonite to expand. In the absence of the Portland additive, this mixture does not harden like concrete so a large quantity of this pre-mix can be kept available in 5 gallon buckets. This pre-mix should be the consistency of a thick soup but not too viscous or creamy. According to the proportions given there should be about three and a half 5 gallon buckets of the pre-mix used for each course. The Portland is added at the time that a batch of slurry is needed to fill the Annular Space for each course. It may be advisable to pour the pre-mix into five separate 5 gallon buckets in equal quantities and add the Portland to each bucket in proper proportions: i.e., .11396 bag or 10.7 lb of Portland per bucket. The reason that some professionals prefer mixing the Portland and water together before adding the Bentonite is that this ensures that proper proportions for the concrete aspect of the grout is obtained, and this is desirable to meet a specified volumetric stability and compressive strength according to regulations. It can be difficult to predict that the entire recommended quantity of Portland can be added to the pre-mix without making it too stiff or too fluid. However, in this application it is possible to adjust the viscosity of the slurry by adding more Portland or more water at the time this is mixed without violating any regulatory specifications. The best method for mixing the Portland into the pre-mix is by using a paddle stirrer attachment on the electric drill – as would be used for mixing paint in a 5 gallon bucket. The desired consistency of the slurry is a thick, creamy batter that will pour like a cake mix. When the slurry is mixed, lower the buckets into the shaft with the block & tackle and pour this directly into the Annular Space, filling it up to just below the height of the mortar of the casing. Scrape as much of the slurry out of the buckets before sending them back up: in order to make the best use of the material and also to facilitate the clean-up process. Note that the Bentonite / Cement Grout Slurry is a slimy, gooey substance that needs to be contained as much as possible. This also contains Portland and will begin to cure as soon as it is mixed. Therefore, the buckets and any tools used in the mixing process need to be rinsed clean with water as soon as possible after they are used. But also, it is best to scrape out and wipe off as much of the unused slurry into a designated holding area before washing with water. This water that is used for cleaning the tools must also be disposed of in a designated area to prevent the Portland and Bentonite from being dispersed into the ground at random. With the grout in place the Slip Form can be set in position to form up the second course and another 2’ high ring of Armature can be installed. At the right, Figure 18 shows that the form is set at least 1” below the height of the first course of mortar. Also, since it does not have a solid surface upon which to sit as with the

Figure 18

Campus Development Series: Book One 26 first course, the Slip Form will need to be suspended at the proper height by driving two large metal or wooden spikes into the Shaft Wall and attaching the form to these with bailing wire. Otherwise, the Armature is installed as for the first course with the overlapping rebar bound together as shown in Figure 16 on page 18. The procedures for forming up the mortar and pouring the grout slurry are the same as for the first course. This will be the method of forming up the casing for the remainder of the height of the shaft, with only a slight modification when the top 5’ where the Annular Seal is located is reached.

At the Annular Seal the diameter of the Shaft Wall is increased to 5’, beginning at a depth about 12” below the boundary between the biologically active soil and the sand / gravel zone. Because of the added depth of the Annular Space it is necessary to increase the spacing on the back side of the Slip Form by 12” by adding a framework to the spacers. It also becomes impossible to use the spikes into the Shaft Wall to suspend the Slip Form in place, so boards laid on the ground above and extending over the shaft opening are used to provide this suspension. Note that the Shaft Wall Support System has been completely removed at this point. Since it is necessary to have the support system in place while working below this level, the additional excavation to increase the diameter is not done prior to this point. Otherwise, the installation of the Armature and placement of the Mortar are done in the same manner as below this level, working up by forming 2’ courses to reach the top. Of course, the volume of the Annular Space at the seal is greatly increases, so the quantities of the ingredients needed to mix a batch of the grout slurry need to be recalculated.

It is estimated that the depth of the bottom of the Annular Seal below ground level will be 5’, but it is also necessary that the Apron has a thickness of about 10”. The volume of the Apron should be calculated separately from the Annular Seal below it, so the actual depth of the seal within the 5’ diameter will be figured as 4’-6” to calculate this volume. On page 19 this was done to determine that the Annular Seal volume will be 77.53 cu ft. There will be 2 ¼ courses to fill within this 4’-6” depth. To find the conversion factor to calculate the amounts of water, Portland, and Bentonite to backfill a single course of the Annular Seal its total volume is divided by 2 ¼ : [77.53 cu ft / 2.25 = 34.46 cu ft per course]. Next, divide this volume by the total volume of the seal: [34.46 cu ft / 164.28 cu ft = 0.21]. Again, multiply the total quantities of each ingredient used for the total volume by this conversion factor to calculate the respective quantities needed for each course of the Annular Seal. [31 bags of Portland X 0.21 = 6.51 bags of Portland per course]. [800 lbs of Bentonite X 0.21 = 168 lbs of Bentonite per course (3.36 bags)]. [919.2 gallons of water X 0.21 = 193 gallons of water per course]. This will be a volume equal to 51.55 ea. 5 gallon buckets, so the grout slurry should probably be mixed in at least 60 bucket batches according to the method given for filling the Annular Space.

Boards overhanging the shaft opening are

used to suspend the Slip Form with bailing

wire.

Biologically

Active

Soil

Sand

Gravel

Zone

Figure 19

Campus Development Series: Book One 27 When the Annular Seal has been filled with grout and the casing is finished to a height of 6” above ground level, it is time to excavate the remaining soil from the space of the Apron and fill this volume with grout. This excavation is to a depth of 10” below ground level. Using the same calculation method as above, divide the volume of the Apron (23 cu ft given on pg 19) by the total volume of Bentonite / Cement Grout (89.5 cu ft) to obtain a conversion factor of 0.25698. Multiply this by the respective total ingredient quantities to calculate the respective quantities needed for the Apron grout. [17 bags of Portland X 0.25698 = 4.369 bags of Portland]. [800 lbs of Bentonite X 0.25698 = 168 lbs of Bentonite]. [919 gallons of water X 0.25698 = 193 gallons of water]. This will be a volume equal to 34.5 ea. 5 gallon buckets, and the grout slurry should be mixed in at least 40 buckets.

Step Eight – Install the Apron Cap and Stand-Up: The casing extends up to 6” above ground level. This provides an initial barrier to surface runoff water during the monsoon season. The remainder of this barrier is the result of the masonry work of the Stand-up and Apron cap. Using native stones to build these features, this stonework is very straight forward. There are really only three criteria that need to be met. The first of these is that when the Apron cap is installed the stones are selected so that this feature is slightly sloped downward from the Well Shaft to the outer edge; this does not to be much but enough to “flash” water away from the well. The second criteria is that the mortar joints are thoroughly consolidated so that the masonry is watertight. And finally, the Stand-Up should be at least 3’ above ground level.

Step Nine – Clean-up: The first and primary concern for clean-up is to ensure that all of the tools and buckets that have been in contact with Portland Cement are rinsed and cleaned as soon as possible and before the mixture cures. And as mentioned before, any surplus of mixed Bentonite / Cement Grout needs to be scraped and wiped clean from these tools and set aside in a holding area. The slurry will actually harden as it will within the Annular Space, Seal, and Apron, and it will become stone-like. This substance does not present a bio or chemical hazard, so this hardened mass can be buried in a place where it will not be a nuisance to agricultural or other landscaping work — perhaps as part of a backfill. The water that is used for this clean-up must also be placed in an area that is contained. The procedures for mixing and pouring the grout for the Annular Seal and Apron indicate that as many as 60 ea. 5 gallon buckets are used to mix the slurry. It is really not likely that there will be this many such buckets present at the work site, perhaps 10 but not 60. So this means that as the slurry is poured and the buckets are emptied they will need to be cleaned out and made available to mix more of the slurry, and this is where the 60 bucket batches are found. They should be wiped relatively clean at this time before mixing a next batch. But the key is that this work will happen at a relatively fast rate, so there is not a problem if there is some mixing of batches. It is once the mixing is completed that the buckets and tools need to be thoroughly cleaned.

3’

Figure 20

Figure 21

Campus Development Series: Book One 28 The other clean-up concerns are that the tools and any unused materials are properly stored and that the scaffolding apparatus is dismantled. There will probably not be a secure structure on the property at this time to serve as a storage facility, so these items will need to be transported off-site to another location until a next phase of construction begins. For the sake of security, this will include the electrical generator and the electric sump(s) used to draw water from the well.

The Finished Well: The purpose of this well is to serve as a water supply for the remaining construction work at the Campus site, so there is not a treatment system added to it at the onset in order to make the water potable. However, at some time in the future it will be desirable to have such a system so that this water can be used to supplement the overall water supply system for the Campus. Plans for such a filtration and treatment system will be given in another booklet. In order to take advantage of the water for drinking while the construction work is in progress, a portable, temporary treatment system can be used, and this will eliminate the need to transport potable water to the site. In addition to providing the initial water supply, this feature will serve as the first “test pit” for soil sampling at and below the depth of the foundations for the other structures on the Campus. Also, this particular project provides an essential exercise in the use of tools and materials that will be used in the remaining construction projects. In particular, the methods of placing Ferrocement and sealing underground tank structures with Bentonite / Cement Grout will be essential in the construction of water storage tanks and the Monsoon Friendly Septic Tank System. With the sump(s) removed from the well the water will rise up to the water table, which should be near the top of the concrete block wall constructed on top of the gravel of the Intake Chamber. However, this water table will be much higher once the Aquifer is replenished from the monsoon rains. In order to use this water upon demand without concerns over recovery time, it will be necessary to have a means of pumping it out at a slower rate over time and storing it in larger volumes. Therefore, the next structure to be built should be a storage tank for this supply of utility water, and the plans for this will also be presented in a separate booklet. It is expected that in the long term the Hand Dug Well for the Vision Bible College Campus will be an important part of the social and educational environment there. Therefore, the ultimate design of this feature will include not only the structure of the well, but also an amphitheater arena to provide a comfortable and attractive space for a variety of presentations and events as well as place for more private activities. For example, this will be a great place to hold baptism services. And what a great place this will be to teach the story of Jesus speaking with the Samarian woman at the well (John 4:6-30)! The illustration on the cover presents an idea of what such a setting might be like.

Campus Development Series: Book One 29

Summary of Tools and Materials Used For This Project: Basic Hand Tools:

Framing Hammer

5 – 10 lb

Sledge Hammer

Pick Adz

Hand Maddox

Pointing Trowel(s)

Wheelbarrow

5 Gallon

Buckets

55 Gallon

Barrel(s)

Hacksaw

Fencing Pliers

Wide – Short

Handled Shovel Sharp Narrow

Shovel

Wheelbarrow

Tamping Rod

with Sharp Point

at one end and

Prying End at the

other

Crow Bar /

Wrecking Bar

Campus Development Series: Book One 30 Power Tools & Equipment:

Manufactured Tools & Equipment:

Gasoline or Diesel

Powered Electric Generator

Electric Lamp

Electric Submersible

Pump(s) / Sump.

At Least 50’ of Garden Hose for

each Sump in use. At Least 3 ea. 50’ Extension Cords

Electric Drill /

Screw Gun Paddle Attachment

For Mixing Grout

Orbital

Palm Sander Circular Saw

Jig Saw

Scaffolding Tripods and Cross Beam

Requires 7 ea. heavy Poles

Block & Tackle

Built from Plywood Basket built From ½

Sheet of Plywood

Block & Tackle

Campus Development Series: Book One 31 Manufactured Tools & Equipment, cont:

See Appendix A for Construction Plans for the Block & Tackle, Slip Form, Basket, and Bosun’s Seat:

Itemized Purchased Materials & Tools:

Materials Unit Price Quantity Total Qy.

Price Fencing Pliers 1 ea. Hacksaw 1 ea. Framing Hammer 1 ea. 5 – 10 lb Sledge Hammer 1 ea. Crow Bar / Wrecking Bar 1 ea. Pick Adz 1 ea. Tamping Rod 1 ea. Wide Short Handled Shovel 2 ea. Sharp Narrow Shovel 1 ea. Hand Maddox 1 ea. Pointing Trowel 2 ea. Wheelbarrow 1 ea. 5 Gallon Bucket 10 ea. 55 Gallon Barrel 2 ea. Electric Generator 1 ea. Lamp 1 ea.

Slip Form requires

2’ X 3’ X 1/8”

Sheet Metal and

1 ½” X 1 ½”

Wooden Spacers

200’ of ¾” Rope for Block & Tackle and

Bosun’s Seat suspension

At least 50’ of ¼” Rope for

Lashing and Rigging

Shaft Wall

Support System

Bosun’s Seat for

Working in the

Well Shaft

Campus Development Series: Book One 32

Submersible Pump / Sump 2 ea. 50’ Extension Cord 3 ea. 50’ Garden Hose 2 ea. Electric Drill / Screw Gun 1 ea. Paddle Attachment 1 ea. Palm Sander 1 ea. Circular Saw 1 ea. Jig Saw 1 ea. 200 feet of ¾” Rope 200 ft. 50 feet of ¼” Rope 50 ft. 1/8” X 2’ X 3’ Sheet Metal 1 pcs. 4’ X 8’ Sheets of ¾” Plywood.

20 pcs.

2” X 4” X 8’ Framing Studs 12 pcs. 1 Gallon of Good Carpenter’s Wood Glue,

Or if possible to obtain use Gorilla

Glue™

1 gal.

15 lbs #8 X 1 ¼” Wood (Sheetrock) Screws 15 lbs 5 Gallons of Waterproofing Agent 5 gal. Portland Cement – 94 lb bag 40 bags Sodium Bentonite – 50 lb bag 16 bags Sand 1.25 ton 800 lineal ft of 3/8” (#3) rebar – should be

available in 10’ joints

80 ea. 10’

pcs.

325 lineal ft of Hardware Cloth

reinforcement wire @ 2’ wide, or 162

lineal ft @ 4’ wide.

Bailing Wire 4 rolls 8” X 8” X 8” Concrete Blocks 78 pcs. Medium Sized Gravel / cu yd 3 cu yd Native Flagstone @ 3” thick – 0.5 cu yd Fuel for the Electric Generator

Human Accommodations: Constructing a Hand Dug Well in this manner is a group project, so there will inevitably be at least four people at the work site at any given time, and possibly even six or more. Although the site for the Vision Bible College Campus is not more than thirty miles from Naktiguda, it would be impractical, time consuming, and even costly to transport this personnel to and from the work site on a daily basis. For one thing, there is some security risk in leaving the site with materials and tools unattended for any length of time. And also, at a point when the Ferrocement work to form the casing begins it is necessary to work around the clock with alternating crews in order to cast a truly monolithic, watertight casing.

Campus Development Series: Book One 33 The practical solution to this problem is to establish a temporary campsite with accommodations for the crew for the duration of the project. Since there will be a need for a shaded area for the workers to retreat from the sun during the day it may be advantageous to set up a large tent near the well excavation site that will serve as a sleeping area with cots, a sufficient supply of fresh - potable water, a kitchen for preparing food, a first aid station, and other basic accommodations. A traditional style

“Tent Meeting” tent would work well for this purpose.[14]

It is probable that the time required to complete all of the excavation and masonry work will be at least two weeks. The amount of food to have available will depend on the number of people present, but this should be relatively non-perishable and easy to serve without elaborate preparations. It is recommended that

adults should have at least ½ gallon of water per day.[15]

The average temperature in Kalahandi District during the month of June is around – at least – 950 Fahrenheit, and this means that working in this heat will increase the need for water consumption and it would be good to plan for a water supply of around one gallon per person per day for drinking, with an extra two gallons per person for hygiene. A 55 gallon barrel of water will last a 6 person crew about 4 days. Having access to four 55 gallon barrels of water for a two week stay at the campsite would be a good estimate.

Of course, there will need to be some form of composting toilet available in the absence of a regular septic tank system. Additionally, a plan for waste disposal must be made. Organic food materials can be composted directly into the soil, but other items should be incinerated on site or packaged / bagged up for removal from the site to a proper solid waste disposal site.

Security for Tools and Materials: There will be a lot of materials and tools delivered to the work site. In particular, the Portland Cement, Bentonite, sand, and the wooden parts of the Shaft Wall Support System should be kept up off the ground and protected from moisture / rain. There should be enough pallets available for setting these products off onto and also a quantity of tarping material – perhaps heavy “Visqueen” – to provide cover. The power and hand tools can be kept under the protection of the tent when not in use.

Logistics: Altogether it is safe to estimate that around 5 tons of materials and tools will be delivered to the worksite, and there must be a sufficient and safe method of transporting these items. The most likely method of doing this will be to use a large, flatbed truck. The first concern in this regard is that there is good access on the property for such a truck to make the delivery directly to the well site. Are the soil conditions adequate

14

Hughesville Friends Church, (Hughesville, PA: Evangelical Friends Website,) Via, http://www.hughesvillefriends.org/15.

(Accessed May 2, 2015)

15

“Water: How much should you drink every day?,” Mayo Foundation for Medical Education and Research, Healthy Lifestyle - Nutrition and

Healthy Eating webpage, http://www.mayoclinic.org/healthy-living/nutrition-and-healthy-eating/in-depth/water/art-20044256.

(Accessed October 25, 2014)

Figure 22

Campus Development Series: Book One 34 to support the weight of such a vehicle? Is there good access from the roadway to the site that is free from ditches and gullies? Because it will be relatively expensive to secure the use of such a truck it should not be expected that it will be available for use longer than is necessary to make the initial delivery of the materials. And logically, this load should be well planned to be certain that everything that needs to be transported is included, and the workers who will be staying at the site may also travel by this method. Otherwise, a smaller vehicle – car or motorcycle – needs to be available at the site for emergency transportation. Necessarily, there will need to be a budgetary allotment for the truck rental and vehicle fuel use.

The Alternate Method of Excavation and Casing Installation: On pg 15 there are two Critical Points identified where the soil may become so unstable that it is not possible to continue the excavation as in the manner used in the upper part of the shaft. One of these is within the Aquifer Zone, and the other is below the Water Table. In particular, within the Aquifer Zone, which may start as shallow as 10 feet below the surface in the Kalahandi District Uplands, the soil composition may become sand and gravel that is not bound together with clay and organic materials so that it is very subject to collapsing if not supported. This condition excludes the option of digging all the way to the Intake Chamber and forming up the well casing as outlined earlier. So it will be necessary to revert to this alternate method if the unstable soil is discovered at the Aquifer Zone during the excavation. Unfortunately, it is not possible to know what the stability of the soil within the Aquifer Zone is before excavating to this level. And also it is very possible that the ground is stable for the entire depth of the shaft to the Water Table and Intake Chamber. Since it is preferable to use the original method of excavation, Shaft Wall support, and casing installation in this particular application, the excavation will be done using the original method at least to the depth of the Aquifer Zone and the soil stability test can be made there. If at this point where the excavation enters the Aquifer Zone, or at any level below this, it is determined that the soil is not stable enough to continue digging down to the water table and then install the casing as desired, then the excavation must stop immediately and this alternate method of excavation below this point and installing the casing must be employed. According to WaterAid – Technology Notes, “The safest method, . . . [of excavating with the shaft wall supported] . . . , is to excavate within pre-cast concrete rings which later become the permanent lining to the sides of the well. The first ring has a cutting edge, and additional rings are placed on it as excavation proceeds. As material is excavated within the ring, it sinks progressively under its own weight and that of the

rings on top of it. This method should always be used in unstable ground.”[16]

Of course this technique is necessary when working in primarily sandy soils that tend to collapse almost immediately when the volume of the well shaft is excavated. However, it is not as easy to work in this manner in more compacted soils containing clay, organic matter, large gravel, and larger stones, which is more like the composition of soil in the area where the Vision Bible College Campus will be located. But it is within the Aquifer Zone where this technique might be necessary.

16

Wateraid.org, Media Publications, “Section 6 – Hand Dug Wells,” Technology Notes, Via,

http://www.google.com/url?url=http://www.wateraid.org/~/media/Publications/technology-notes-

2011.pdf&rct=j&frm=1&q=&esrc=s&sa=U&ei=wz4bVceaGKThsATT2oLwCQ&ved=0CCIQFjAA&sig2=NCt6xam1v5lXH7-

OkZNmZw&usg=AFQjCNEQ9y30Ftwp9hO8N_ZKhEoKws3b5w. (Accessed January 20, 2015)

Campus Development Series: Book One 35 If it is determined that it is necessary to revert to this alternate method when the Aquifer Zone is reached, then it will also be necessary to form up the Well Casing above this level and placing the Portland / Cement Grout – completing the Annular Seal and Apron - using the original method. The main difference with starting the forming of the casing at this level rather than on top of the Concrete Block Wall at the Intake Chamber is that a Curb is used as the foundation for the casing. This Curb is cut into the Shaft Wall at least 1’ above the level of the Aquifer Zone where the soil is still solidly packed. It must be at least 1’ foot into the wall and 10” thick to provide an adequate footing for the casing. The vertical rebar of the Armature is bent to provide reinforcement within the Curb. Similarly, at least one additional Curb(s) is/ are formed into the casing at higher levels to secure the casing to the Shaft Wall. Challenges of Placing Pre-Cast Caissons:

Placing the precast rings, also called “Caissons,” in this manner presents some interesting challenges. To begin, these rings are lowered into the shaft inside the casing that has already been finished, so there must be about 1 ½” clearance all around between the inside of the casing and the outer circumference of the rings. Given that the Annular Space is 1 ½”, the casing is 3”, and the clearance is 1 ½”, then the outer diameter of the Caissons will only be 3’. If the walls of these rings are 2 ½” thick, then their inside diameter will only be an inch over 2 ½’ – or 31”. This makes for a very tight working space, but it is possible to do this.

The video at the URL in footnote[17]

shows this work being done using Caissons that are 3’ OD X 18” high. In the video, the crew is working from ground level and placing the rings directly on the stack without any block and tackle assistance. Because the well at the Vision Bible College Campus has already been dug down to the level of the Aquifer Zone it will be necessary to lower the Caissons down to that level using Block & Tackle. It is also necessary to use a sling that supports the Caissons from the bottom with rebar hooks, (see Figure 24).

17 “Digging Infiltration Absorption Wells,” Found via the SurvivallandUSA Website - http://www.survivallandusa.com/How-To-Dig-A-

Well.html. Video URL, https://www.youtube.com/watch?feature=player_embedded&v=PXqg5yiCvhg. (Accessed May 4, 2015)

Figure 23

Hard

Compact

Soil

Porous Sand

And Gravel

Aquifer Zone

Special hooks

grab the bottom

of the rings as

part of the

lowering sling

apparatus.

The ring stack

sinks into the

shaft as the soil

around the

circumference is

cleared away.

Figure 24

Figure 24

Campus Development Series: Book One 36 A second challenge is that the individual Caissons are heavy. At 2’ high these precast rings have a solid volume of 3.628 cu ft and weigh 545 lbs. Reducing the height to 18” as in the video the volume is 2.721 cu ft and the weight is 409 lbs. This is significantly more weight than any of the loads of soil and masonry that are moved with the block & tackle system in the original casing method. Therefore, it will be necessary to use two block & tackle to lower the rings into the shaft (as shown in Figure 25), and also these must be rigged to increase the mechanical advantage to a ratio of four to one ( 4:1 ).

The third major challenge is that the Caissons will probably have to be cast on site. This requires that at least one precast form is available, and also it will impose additional labor time to the project since it is necessary that a Caisson cures in the form for at least 16 hours before the form can be removed and re-set for another casting. Supposing that the use of Caissons begins at the 10’ depth, then there will be a need for a 20’ stack of Caissons to finish the well to the base of the Intake Chamber. A total of 10 ea. Caissons at 2’ high or 14 ea. at 18” high will be needed to obtain this height. It is possible that precast Caissons of this type with a 3’ outside diameter at 18” or 2’ high are available locally. Unfortunately, these tend to be relatively expensive to purchase. Since the materials to construct the Ferrocement casing will be available at the worksite at this time anyway, it will be most feasible to use the available material and labor resources to produce the Caissons on site.

Building Forms for Precast Caissons: Step one – Assessing the Available Materials: The first resource to consider is that there are 96 Vertical Boards @ ¾” X 6” wide X 8’ long that were cut for the Shaft Wall Support System. Given that the casing has now been installed in the upper level of the shaft (10’) and the Support System is not used with this Alternate Method of sinking Caissons, then these boards are available to be modified into a set of precast forms.

Figure 25

The Caisson Sling

is designed to lift

straight up on the

rings from the

bottom. The

Caissons are cast

with four notches

in their bottoms to

allow the rebar

hooks to slip out

once they are

placed onto the

stack.

The mechanical

advantage of the Block

& Tackle is increased

from 3:1 to 4:1 by

adding a pulley to the

movable block and

fastening the rope to the

fixed block. So now

there are four movable

pullies in the system,

and a load of 200 lbs

can be lifted with a pull

of 50 lbs.

Figure 26 Figure 27

Campus Development Series: Book One 37 The 4’ diameter Shaft Wall requires 24 Vertical Boards to go around the complete circumference, which is 150.79”. The circumference of the outside diameter of the Caissons is 113.1”, so it only takes 18.85 boards @ 6” wide to go all of the way around. Likewise, the circumference of the inside diameter of the Caissons is 97.39” and only 16.24 boards are needed to go all the way around. Therefore, it takes 35 ea. 6” boards to make the walls for a single form. Due to the weight consideration and lifting capacities of the Block & Tackle system it is preferable to cast the Caissons at 18” high. So if the 8’ Vertical Boards are cut into 18” lengths there will be 5.33 pieces per board – or 5 full 18” boards available in each Vertical Board. Overall there will be 480 ea. 6” X 18” boards available in the 96 original Vertical Boards, which is enough to build 13 precast forms. This is enough to cast nearly all of the Caissons in a single batch. However, after considering the availability of other materials it will be seen that it is most efficient to build only 7 precast forms and to cast the total 14 Caissons in two batches. Next, there will be a difference in the quantities of rebar and hardware cloth used to make the Armatures for these Caissons at the smaller diameter than were calculated for the original casing. Consider that the diameter at the center of the Caisson wall is 33.5”, then this circumference is 105.25”. The Armatures will be built up in the same manner as for the casing wall except that they will only be 16” high, allowing an inch at the top and bottom of the Caisson for encasement of the Armature. There will be two horizontal rebar rings per Caisson and each of these will be made of two pieces @ 60” long bent to fit the circumference. These will have a 4” overlap at each end for binding together with bailing wire. There will also be 5 ea. vertical pieces of rebar at 16”. So the total footage of rebar per Caisson will be 26.66 lineal feet of rebar per Caisson, and with 14 ea. Caissons this will be a total of 373.25’ of rebar to precast the Caissons (38 ea. 10’ joints). The original materials calculation calls for 800’ of rebar to make the Armature for the casing. This becomes 32’ of rebar per 1’ of casing. At 10’ of finished casing there will only be 320’ of the 800’ of rebar used in the finished 10’ section of casing, so there will be 480’ of rebar available for building the Caisson Armatures. And there will be 106.75’ of the original 800’ of rebar that are not used in these Caissons. Of course, a small part of this material will be used to make the hooks for the Sling. Similarly, there will need to be 20 lineal feet of hardware cloth in the Armature for each Caisson. These lengths of wire mesh will also only be 16” high. So if this material is purchased in rolls that are 4’ wide it will be possible to cut three 16” pieces from this width. The materials estimate calls for 162 lineal feet of hardware cloth @ 4’ wide for the original casing, and this is 6.48’ per foot, so that only 65’ of this is used in the finished casing. There will be 97 lineal feet of hardware cloth available to build the Caisson Armatures, but only 93’ will be needed and there will be a 5’ length left over.

Step two – Building the Inside of the Form: In planning the design and construction of the precast forms the first and foremost consideration is how much pressure the walls of the forms must sustain. “This is the [horizontal] pressure that fluid concrete exerts on the forms that restrain it and is determined primarily by the height of the fluid concrete that is placed into the forms. This height of fluid concrete is commonly referred to as the liquid head. . . . The following formula provides a rough estimate of the pressure from liquid concrete:

p = 150 x h and: h = p/150 where: p is the pressure in pounds per square foot, psf; h is the height of the fluid concrete (liquid head), in feet. (150 is the weight of normal concrete pounds per cubic foot)

Campus Development Series: Book One 38 “A limited pour rate will provide time for the concrete to begin hardening and thus reduce the height of the fluid concrete. Therefore, placing the concrete slowly will result in reduced pressure on the forms and

diminish the possibility of form failure.”[18]

Applying this formula for a form height of 18” returns a value of 225 psf at the base of the form when the concrete is totally fluid. However, in this case there will be 7 separate forms to fill in each batch, so a limited pour rate will be possible as a height of about 6” can be placed into the first form, then repeating this in each of the other forms will allow for some set-up time in the first form before another 6” layer is added. Also, the same mortar mixture that was used in the original casing will be used. This has a slump of around 2.5, which is relatively stiff and will make for a faster set-up time. With these factors considered it is safe to estimate that the actual pressure on the form walls at any given time will be more in the range of 75 psf - 100 psf, and the forms need to be constructed accordingly. When finished the precast forms will look like Figure 28 at the right. There will be two wooden rings inside that support the inner wall in a manner similar to the rings of the Shaft Wall Support System. These rings also need to be manufactured, and similarly, arc sections of full rings will need to be plotted onto full sheets of ¾” X 4’ X 8’ plywood. Figure 29a below shows that each full plywood sheet will render a total of 18 one third circumference arc sections, which is 6 ea. full rings.

18 Scaffolding, Shoring, and Forming Institute, Inc. “Form Pressure and Pour Rate Basics,” SSFI Technical Bulletin, SSFI Forming Section

Website, Via, http://www.saiaonline.org/userfiles/file/SSFI/Form%20Pressure%20and%20Pour%20Rate%20Basics.pdf.

(Accessed May 5, 2015)

The outer wall is supported

with Hardware Cloth / Mesh.

Figure 28

Scabs for joining the

arc sections are cut

from the “off-drop”

in the voids between

the arc sections.

Figure 29a

Campus Development Series: Book One 39

Three ea. arc sections butt together at their ends to form a full ring. The joints are held together with scabs cut from the “off-drop” in the voids between the arc sections. Since there are 7 forms to build with 2 rings per form there will need to be 14 rings total. At 6 ea. full rings per sheet of plywood it will take 3 sheets to construct all of these rings. This is additional material that will need to be purchased.

The inside diameter if the Caissons is 31”. The thickness of the upright plywood boards is ¾”, so the diameter of the inside of the inner wall will be 29 ½”, and the relative circumference at the inside of the plywood will be 92.677” = 92-5/8”. It will be necessary to lay out 15 ea. boards at 6” width plus another that is cut down to 2-5/8” in order to create a length that will wrap around to form a circular wall at this dimension. Begin by laying the boards out side by side with their bottoms flush with the edge of a full sheet of plywood. Be certain that the boards are tight together and tape each joint securely along its full length with duct tape. If possible use Gorilla Tape™ brand tape. When the full 92-5/8” length has been taped together and the assemblage is stood up on end the tape joints will act as hinges to allow the wall to form up into a cylinder, functioning in the same manner as a “roll-top desk” panel. While the panel is still laid out flat set a row of screws in line at 3” from what will be the bottom of the wall and also mark the line at 3” from the top of the wall. To set the form there will need to be a flat, level space on the ground at least 3’ in diameter. When this is prepared, set the panel for the inner wall up on edge and form it into a cylinder, joining the two loose ends together with the tape. Drop a support ring into place so that it rests on the bottom screws. Next, set several screws around the circumference at the upper line and drop another support ring onto these. The wall should now be perfectly cylindrical and supported all the

Unlike the Shaft Wall Support System rings, which apply pressure to the Vertical Boards with wedges, the rings in the Caisson forms are in direct contact with the inside face of the boards of the inner wall. These rings define the circumference of the inner wall. They are installed at heights of 3” from the bottoms of the forms and 3” from the tops.

the liquid concrete the inner wall will tighten up against the rings. When the concrete has set up for about 16 hours these screws are removed and the rings are hammered up out of the form. This allows the boards of the wall to relax to the inside to release the concrete from the form.

The rings are supported inside the inner wall by screws driven into several of the upright boards around the circumference to act like shelf brackets. Under the pressure of

Figure 30

Figure 29b

Figure 31

Campus Development Series: Book One 40 way around by the two support rings. Finish the inner wall by taping each of the joints between the boards from top to bottom on the outside.

Step three – Install the Armature: Constructing the Armatures is done in the same manner as it was for the original casing except that it will only be 16” in height and does not bind together with another course at the top: i.e., it is entirely encased within the wall of the Caisson. The radius to the center of the Caisson wall is 16.75”, which is the radius to which the horizontal rebar pieces must be bent. The best way to obtain this bend is to inscribe an arc of this radius onto a sheet of plywood and work the 60” pieces of rebar by hand until they conform to the arc. When these pieces are properly shaped set them around the inner wall two at a time and bind the overlapping ends together to form a solid ring that is offset from the wall by 1” all the way around. Prepare two of these rings for each form.

Next, wrap the inner wall with a piece of hardware cloth that is cut at 16” high by 9’ long. This is

placed inside the circumference of the two rebar rings. Bind this mesh into a cylinder that is offset from the inner wall by 7/8” all around, and this should be tight against the inside of the rebar rings. Lift the top rebar ring up to 2 ½” from the top of the wire mesh and bind it to the mesh there. Likewise, lift the lower rebar ring up to 2 ½” from the bottom of the mesh and bind it there. Now bind the 5 vertical rebar pieces to the horizontal rings & mesh at equal spacings around the circumference. Finish the Armature by wrapping it again with a piece of hardware cloth that is also cut at 16” high by 9’ long. Place stones Beneath the Armature around the circumference to lift it up by 1” all around, which should also raise it to 1” from the top for encasement. When finished the Armature should be offset from the inner wall by 7/8” all the way around.

It is necessary to install a set of “block-outs” at the bottom

of the form to provide a void where the Sling hooks can slide out when the Caissons are set onto the stack. This is done by placing four pieces of 2” X 4” cut to 2 ½” lengths at the base of the form. These are placed to stand upright so that the resulting slots are 3 ½” high by 1 ½” wide. It will be necessary to cut the two bottom strands of wire in the Hardware cloth and bend these out of the way, and the blocks should fit just beneath the bottom of the horizontal rebar ring. These blocks are set at the four quarter arc positions around the circumference. It is important to ensure that these blocks do not shift position when the mortar is placed into the forms, perhaps by binding them in place with bailing wire. These block-out slots will be filled with mortar when the Caissons are in place.

Step four – Setting the Outer Wall: The outside diameter of the Caissons is 36”, which is a circumference of 113.1”. It will take 18 full 6” boards and one at just slightly over 5” in width to make a panel of this length. This panel is taped together in the same manner as the panel for the inner wall and then wrapped around the standing inner wall and Armature. It is only necessary to tape the outside of the joint where the two loose ends come together. The pressure of the fluid concrete will be held by a tight wrap of hardware cloth around the outside of the outer wall. This length of hardware cloth is also 16” wide but will need to be 10’ long to overlap sufficiently. These 7 ea. pieces of mesh (cut at 16” high X 10’ long) are available within an additional 30’ of the hardware cloth in a 4’ roll. This is also an additional material that must be purchased to build these precast forms.

With the hardware cloth wrapped around the form use bailing wire to pull up all of the slack at the

overlap joint to make the mesh fit as tightly as possible. Tie this overlap together as securely as possible with bailing wire so that this will not slip when pressure from the fluid concrete comes against it. This outer wall

Figure 32 Ground Level

Campus Development Series: Book One 41 does not have the advantage of the supporting rings to ensure that it is perfectly cylindrical, so it is important to be certain that it is offset from the inner wall by 2 ½” all around the circumference while placing the mortar. And now the forms are ready for the placement of the mortar.

Placing the Mortar Into the Forms: The first two Caissons to be lowered into the shaft will make up the 36” depth of the Intake Chamber that is also packed with gravel. Logic suggests that these need to be porous in order to allow for water infiltration into the well. The Intake Chamber of the original In-Situ casement procedure is constructed entirely of medium sized gravel for a depth of 3’, and the remainder of this 2’ up to the top of the Water Table is a concrete block wall. So there is plenty of void space in the structure to accommodate a desirable recovery rate. If the bottom Caissons are made with a thoroughly consolidated mortar mix so as to be watertight then the only porous openings into the Intake Chamber are at the floor of the shaft below the level of the Caissons and also at the joints between these first two Caissons. The question is, does this provide sufficient percolation to support an adequate recovery rate and yield? As in the case of mixing the ingredients for the Bentonite / Cement Grout, there are proponents of both methods here: i.e., using either porous or solid Caissons in the Intake Chamber, and both methods seem to have their advantages. According to Stephen P. Abbott, a specialist in dug well and sanitation system constructions in rural India, “There is almost never any need for perforations of the caisson rings or for the use of permeable mixtures of cement. The water enters easily through the joints between caissons and from the bottom. Some workers in the field have speculated on the need to use porous caissons in the intake section of the well. Such misconceptions likely result from the very real need for these measures in the case of In-Situ lining. In India in the 50's and 60's, only solid concrete caisson rings were in use for well construction. We are not aware that the water ever had any difficulty entering the wells. “Those who felt it necessary have tried both porous concrete, and weep holes cast in the caisson walls. We do not encourage the use of either of these solutions, as one weakens the concrete drastically and can cause spawling due to corrosion of the reinforcing rod, and the other vastly complicates and increases the cost of the necessary moulds. If designers insist on using porous caissons, however, we suggest they opt for the use of

weep holes, as the use of porous concrete is far more dangerous.”[19]

The primary danger that Abbott refers to is the possibility of Caisson failure due to the weakened cement composition. Naturally, if the support capacity of the Armature is compromised due to the corrosion of the iron then this potential for failure is increased. Such a failure could be catastrophic because these two Caissons in question are at the very bottom of a stack of 14 Caissons and are essentially supporting a weight of around 5844 lbs (almost 3 tons) above them. These two rings (the bottom 3’ of the Intake Chamber) will be completely filled with firmly packed medium sized gravel once the well is completed and operational. This should provide plenty of support to prevent any collapsing at that point. However, if there should be a failure of these Caissons as the stack is lowered during the excavation process there is no chance that they can be replaced. At best it may be possible to remove their debris from the shaft, thereby allowing the third, solid

19

Stephen P. Abbott, Hand Dug Wells: Choice of Technology and Construction Manual, pgs 11-12,

Via, https://www.google.com/url?url=https://www.oxfam.org.uk/equipment/catalogue/resources-included-available/water-and-sanitation/well-

digging/handdugwell-

BOOK.pdf/at_download/file&rct=j&frm=1&q=&esrc=s&sa=U&ei=yaZLVYKQJ8vWoASK34H4DQ&ved=0CDYQFjAH&usg=AFQjCNHU0MxQ

wJTr3-Nhbj7VZ3M432ngnA. (Accessed May 6, 2015)

Also Found Via, http://www.sswm.info/sites/default/files/reference_attachments/ABBOT%204000%20Hand%20Dug%20Well%20Manual.pdf.

(Accessed May 6, 2015)

Campus Development Series: Book One 42 Caisson above them to assume the position of being the bottom Caisson. The safety factor of doing this additional work is questionable to say the least since the entire stack of Caissons will tend to fall into place as the debris is removed. And overall, if such an incident should occur this would dictate that additional time and materials are spent to not only clear away the debris but also to re-cast two solid Caissons to replace those that have failed in the total height of the stack. On a similar note, it is impossible to predict in advance what the exact characteristics of the ground within the Aquifer Zone at a level below the Water Table will be. For example, it is not known in advance how deep the Aquifer Zone is or how far below the Water Table this zone reaches before a layer of solid bedrock or impervious clay is reached. It is hoped that the shaft can be excavated to a depth of 5’ below the Water Table, with the lower 3’ of this Intake Chamber filled with compacted gravel. However, if it happens that at this depth the ground has become relatively impervious to water flow, then depending on the opening at the bottom of the Caisson stack may not be adequate to support the desired recovery rate and yield. It is for this reason that logic suggests the use of porous Caissons for this first 3’ in the Intake Chamber. This choice must be made before the lowering of the Caissons begins because it is also impossible to change those two bottom Caissons after that point.

The only way to really determine if the Porous Caissons can be cast at the worksite and be sufficiently strong to lower into the shaft with a full load of Caissons on top of them is to make them up with the first batch of Caissons. There is no difference in the way the forms are set up except that it is recommended that twice as many vertical rebar pieces are used in the Armature (total of 10) than for the Monolithic Caissons. The difference in the casting is in the cement mix. To make a porous concrete mix pea sized gravel – about ½” to ¾” in diameter – is used instead of sand. Also, much less water is added to the mix than for the 2.5” slump mortar used in the Monolithic Caissons. In fact, porous concrete mixtures are not considered to have a slump as this is figured for fluid concrete mixes.

Note that the bottom of the first Caisson to be lowered is often cast with a knife edge for cutting the soil as it sinks. This may provide an advantage in some soil conditions, but as is seen in the video referenced on page 33, this is not essential as the undercut digging actually removes any soil blocking the path of the sinking Caisson stack. Because the proportions for pervious concrete mixes are so critical three competent sources are cross-referenced here to ensure that proper proportions are given. Each source also provides a good technical discussion of the characteristics of permeable concrete as well as methods of placement and performance parameters. According to the first source, Earthcare Landscaping; “The basic pervious concrete mix is: 3 parts rock - 1 part loose cement - just enough water. “Unlike regular concrete, the correct amount of water to add to pervious concrete lies within a very narrow range, if you add a little too much you could end up with impervious concrete and if you add too little you might get raveling (loose rocks on the surface) later. The general rule of thumb to know if the water amount is correct is to make a ball (wearing gloves of course) and the ball should hold together and have a

nice shine to it.”[20]

(See Figure 34 below).

20

EarthCare Landscaping, “How To Make Pervious Concrete,” How to make porous / pervious concrete for homeowners, (2010, )

Via, http://earthcareland.com/blog/tag/how-to-make-pervious-concrete/. (Accessed May 7, 2015)

Peas sized gravel

creates voids in the

Caissons.

Figure 33

Campus Development Series: Book One 43 Similarly, the National Ready Mixed Concrete Association has this to say; “Proportioning pervious concrete mixtures is different compared to procedures used for conventional concrete and the mixture proportions are somewhat less forgiving than conventional concrete mixtures—tight controls on batching of all of the ingredients are necessary to provide the desired results. “When developing pervious concrete mixtures, the goal is to obtain a target or design void content that will allow for the percolation of water. The void content of a pervious concrete mixture will depend on the characteristics of the ingredients, how they are proportioned and how the mixture is consolidated. Pervious concrete is typically designed for a void content in the range of 15% to 30%. Generally as the void content decreases, the strength increases and permeability decreases. For pervious concrete mixtures it is even more important to verify through trial batches that the mixture achieves the characteristics assumed or targeted when developing mixture proportions. Frequently one finds that even though the design void content is 20%, when the pervious concrete mixture is proportioned, the experimentally measured void content is considerably

different. This depends on the workability of the mixture and amount of consolidation.”[21]

Table 3 - Typical Ranges of Materials Proportions in Pervious Concrete (Adapted from “Materials and Mix Design”)

Proportions, lb/yd³ Proportions, kg/m³

Cementitious materials 450 to 550 267 to 326

Total Aggregate 2000 to 2500 1190 to 1480

Water: cement ratio*** (by mass) 0.27 to 0.36 ——

Fine aggregate 0 to 500 lbs 0 to 297

Figure 34. Samples of pervious concrete with different water contents, formed into a ball: (Adapted from “Materials and Mix Design”)

(a) too little water, (b) proper amount of water, (c) too much water.

And finally the UN – FAO proposes this ratio for well casing / Intake Chamber porous mixtures; “A suggested ratio of cement: sand : coarse aggregate is 1:1:4. Porous concrete thus made is considerably less

21 “Materials and Mix Design,” Concrete Answers Series for Architects, Engineers and Developers, (Silver Spring, MD: National Ready

Mixed Concrete Association, 2011, ) Via, http://www.perviouspavement.org/materials.html (Accessed May 7, 2015)

Campus Development Series: Book One 44 dense and strong than normal concrete. It should, therefore, be made with more reinforcing and be handled more carefully than conventional concrete. This method does, however, provide a large infiltration area and

prevent fine material from entering the well.”[22]

Note that this proportion includes a small quantity of sand, which is not included with the other mixtures. This amount is practically negligible compared to that used in the mortar for the Monolithic Caissons and it only serves to help suspend the Portland Cement in the mixture.

If the mixture contains too much water, as shown in picture (c) of Figure 34, the Portland will wash down to the bottom of the form, filling the voids there and causing this area to become impervious while not providing enough binding capacity in the upper part of the form to hold the aggregate together. In the optimum mixture, as shown in picture (b), the Portland and water is mixed to the consistency of a thick paste much like peanut butter that does not flow – just enough moisture to hold the aggregate together.

Two additional feature of pervious concrete that are important to note are, for one, it is not a fluid concrete mix and does not apply a “liquid head” pressure in the form like the mortar does. Also, because of the low water content the mixture sets rapidly, and because of the nature of the mixture it is not possible to add water in order to retard this curing time. Therefore, it is necessary to place the pervious mixture and work the forms as fast as possible once the ingredients are mixed.

It is most efficient to mix the pervious concrete in a wheelbarrow where it can be turned with a shovel to thoroughly coat the aggregate with the Portland paste. To place the concrete, use a shovel to drop the mixture into the forms, working around the circumference by a shovel-full depth at a time. As the mixture falls to the bottom of the form use a piece of rebar to tamp it so that it compacts as much as the gravel size will allow, but being careful to not over-consolidate so that the Portland paste tries to flow into the voids. The objective is to ensure that there are no large holes in the casting where the mixture has failed to compact. Because the volume of the total void in each Pervious Caisson is unpredictable it is not possible to estimate exact quantities of Portland, gravel, and water in the needed mixture. But it is known that the full volume of each precast form is 2.721 cubic feet. Given a general ratio of 3 parts gravel to one part Portland with a small amount of water, then there will be about 0.55 cu ft (51.1 lbs) of Portland and 2.04 cu ft (194 lbs @ 95 lbs / cu ft) of gravel in each Caisson. Otherwise, work the mixture up in smaller batches in the wheelbarrow to ensure that the proportions are correct for the desired consistency – working quickly so that the batches do not set while the placement is in progress. Fortunately, the calculations made on page 18 provide a ratio for mixing the mortar to fill the remaining forms for the Monolithic Caissons. Each form @ 2.721 cu ft will require 29.54 lbs of Portland, 97.76 lbs of sand, and 3.36 gallons of water (169 lbs). So to fill the 5 ea. forms for the first batch the mortar mixture will require 147.7 lbs of Portland, 488.8 lbs of sand, and 16.8 gallons of water (845 lbs). The mixture for the second batch of 7 ea. Monolithic Caissons will require 206.78 lbs of Portland, 684.32 lbs of sand, and 23.52 gallons of water (1183 lbs). And again, as this mortar is being placed fill each form to a height of only 6” and work to consolidate this first before going back to add another level of 6” to each form in succession. This will allow the mortar at the bottom of the forms to begin curing and thus reduce the “fluid head” pressure in the forms to a range of 75 – 100psf. When the concrete has cured for a minimum of 16 hours it is possible to release the forms. Begin by releasing the bailing wire bindings at the overlap joints of the Hardware Cloth that is wrapped around the outer walls and remove this support. Next remove the tape on the butt joint of the loose ends of the outer

22

Food and Agricultural Organization of the United Nations, “5. Large diameter wells,” Produced by: Natural Resources Management and

Environment Department, Fao Corporate Document Repository, Via, http://www.fao.org/docrep/x5567e/x5567e06.htm (Accessed May 7, 2015)

Campus Development Series: Book One 45 wall panels and remove the panels. Now use a hammer to tap the top inner support rings up and out of the forms. Note that the screws that supported these top rings will have to be removed before the lower rings can also be tapped up and out of the forms. Note that it may be necessary to remove the support rings by removing one or more of the scabs holding the butt joints of the arc sections together. Now it is possible to remove one of the tape joints on the inner wall panel and flex the two adjoining boards inward to create slack in this panel so that it can be removed. And the Caisson rings will be free-standing at this point. It is good to wash over the Monolithic Caissons with water to add moisture and extend the curing time, but not good to risk any wash out of the Portland in the Pervious Caissons by doing this. Allow the Caissons to stand for another 8 hours in open air before lowering them into the shaft. However, it is possible to reassemble the forms to prepare the second batch of Caissons as soon as they are removed.

Lowering the Caissons Into the Well Shaft: When working from ground level to use Caissons for the entire depth of the shaft it is not necessary to use any elaborate lifting apparatus. However, in this case the In-Situ Ferrocement casing has already been installed to a depth of around 10’. Therefore, it is necessary to lower the bottom Caissons down to this level using the Block & Tackle with the Sling. It is expected that if the Caissons are used for the entire depth of the Aquifer Zone, which may begin at the 10’ depth, the total Caisson stack will be around 20’ high. This means that 7 ea. Caissons may be stacked up before the undercutting begins, and this will raise the top of the stack up to ground level. At this point it will be possible to add the remaining 7 ea. Caisson rings to the top of the stack at ground level as the undercutting begins and the stack sinks. But still, it is necessary to use the Block & Tackle to build the stack up to ground level in order to begin. Once the total of 14 ea. Caissons have been stacked up together the top of the stack will then lower down into the shaft until the desired depth of the excavation is reached.

Figure 35 at the right[23]

illustrates the cross-section of a well with an In-Situ Ferrocement casing for the upper level and a sunk Caisson stack for the remaining depth of the shaft into the Intake Chamber. When fully installed the overlap between the base of the Ferrocement casing and the top of the Caisson ring stack will be about 1’. There should be a 1 ½” gap all around the circumference between the larger diameter casing and the smaller Caisson, and this will be filled with mortar to make a watertight seal.

23 Stephen P. Abbott, Hand Dug Wells: Choice of Technology and Construction Manual, pg 10,

The upper level

of the Well Shaft is cased

with In-Situ Ferrocement

to a depth of 10’. Note

that Curbs are included in

the design to serve as

footings to prevent the

sinking of this casing.

Once sunk to the

full depth of 30’ to the

level of the Intake

Chamber, the top of the

Caisson stack will only be

about 1’ above the base of

the upper Ferrocement

casing.

Figure 35 Illustration from: Hand Dug Wells: Choice of Technology and Construction Manual

Campus Development Series: Book One 46

Attaching Caissons Together:

“One of the greatest challenges in caisson sinking is to prevent the bottom ring in the stack from falling out of line. In order to sink the caissons, they must be undercut. Without suitable precautions, one side of the bottom ring can fall ahead of the other. When this happens, that side tends to fall inwards. When the other side is induced to come down, it tends to move outwards so that the caissons are no longer aligned. After this happens it is very difficult to correct the situation or to prevent it from worsening. There is, however, a simple and effective method to prevent the problem.

“During caisson sinking the bottom three to six caissons are temporarily bound together with steel rods. . . . It is recommended that the binding rods be attached as soon as there are more than two caissons to join together. When problems develop it is already too late. In the event that one side of the bottom caisson separates before the rods are in place, the excavation should be stopped while the attempt is made to lift the bottom ring back into place and

attach it.”[24]

The situation that Stephen P. Abbott

describes here and illustrates in Figure 36 is easily prevented by bending 4 ea. of the 10’ joints of 3/8” rebar to act as cleats to hold the bottom 6 ea. Caissons together while the excavation progresses. One end of the joints is bent into a hook similar to those used in the Sling. The hooks grab the bottom of the Caisson stack through the same knock-out slots used by the Sling hooks. The tops of the joints are bent at 90 degrees so that the cleats are about 106” long. Short wedges hold the rebar tightly to the top of the Caisson stack, allowing the knock-out slot of the 7th Caisson to straddle the rebar, and thus the bottom 6 ea. Caissons are held tightly together.

24

Stephen P. Abbott, Hand Dug Wells: Choice of Technology and Construction Manual, pg 27,

Figure 36 Illustration from: Hand Dug Wells: Choice of Technology and Construction Manual

Figure 37a

Figure 37b

Campus Development Series: Book One 47

Positioning the Caissons Over the Well Shaft:

According to “Weight per Volume” calculations

for concrete structures[25]

, the weight of the 18” Caissons at 3’ diameter with a 2 ½” wall is around 409 lbs each. The actual quantities of materials in the mortar mixture per Caisson given on page 42 indicate that this weight is more at 350 lbs, including the iron in the Armature. In either case, the individual Caissons are heavy and require a crew of three or four people to move around. In particular, the Caissons need to be moved from where they are cast into position on top of the Well Shaft so that the Sling and Block & Tackle can be set to lower them into the shaft. For the most part the Caissons can be rolled around, but they will eventually need to be lifted onto the shaft, where they are supported by two 2 ¼” thick planks while the Sling is set and tension is taken up with the Block & Tackles. Recall that the ferrocement casing is built up to a height of about 10” above ground level. This means that there must be a safe method of raising the Caissons up to this level in order to maneuver them onto these plank supports. Perhaps the best way to do this is to build up a ramp using another pair of 2 ¼” thick planks. These four planks can be constructed by laminating the Vertical Boards used for the Shaft Wall Support System together, using 3 ea. boards per plank. It is advisable to screw the individual boards together to facilitate solidity and the overall support capacity.

Figure 39 at the left[26]

shows a Caisson suspended with a single Block & Tackle with the support planks removed. Note that with this set up a “Break Post” is used to provide control over the rope. This safety measure is particularly essential in a system where two Block & Tackles are used in order to regulate the rate at which the ropes are paid-out so that the two sides of the Sling are lowered in concert. It is assumed that the two Pervious Caissons are sufficiently solid to use in this application. If it turns out that

they are not adequate, then set them aside and use Monolithic Caissons to begin the stack. Build the stack up to a full 7 ea. Caissons, which should be at the same level as the top of the Ferrocement casing, and set the four cleats on the lower 6 ea. Caissons before beginning the excavation to undercut the rings and lower the stack. Add a next Caisson each time the top of the stack levels off at the top of the casing until all of the 14 ea. Caissons have been placed. Although most discussions of this procedure recommend sealing the Caisson joints with mortar to make them watertight, it is really impractical to do this while the stack is being lowered because there is too much potential for shifting at the joints, thereby breaking the watertight seal of the brittle mortar. Also, all of these Caissons will be within the Aquifer Zone anyway, and there is really no danger of biological contamination of the water at this level. However, it may be useful to adhere these joints with Gorilla Glue™

25 Concrete Calculator - Volume vs. Weight, Via, http://www.traditionaloven.com/conversions_of_measures/concrete-weight.html.

(Accessed November 12, 2014)

26 Food and Agricultural Organization of the United Nations, “5. Large diameter wells.” (Section 5.5 , Figure 50).

Figure 38

Figure 39 Illustration from: UN – FAO, “5. Large diameter wells”

Campus Development Series: Book One 48 or a good silicon masonry adhesive in order to keep the Caissons from slipping out of alignment during the lowering process. But note that both of these products require a setting time of at least 30 minutes to provide the desired adhesion. Do this for all of the Caissons except for those that will be below the Water Table. This is the Intake Chamber and it is necessary that these joints between Caissons here are NOT sealed in order to provide infiltration of water.

Excavating the Undercut: There is much less working space within the 31” inside diameter of the Caissons than there is inside the original Ferrocement casing. Obviously it will not be possible to use the same tools for this excavation that were used in the original excavation. For one, it is not possible to lower the basket used for removing soil into this small space, so a small bucket is used instead. Also, even the small handled shovel is too large for working within the Caissons, so a smaller hand scoop is used to load the loosened soil into the bucket. The method of loosening the soil so that it can be scooped away is also different. This will require the use of a small hand pick, a small mining bar, and a chisel and hammer for breaking up rocks. And the actual undercutting around the circumference is done with a pointing trowel.

Continue undercutting the Caissons around the circumference and removing the soil in the shaft until the stack is lowered to the desired depth of 5’ below the water. It will be necessary to use the Sump(s) to evacuate infiltrating water when digging below the water table. When the bottom of the Intake Chamber is reached it is necessary to install a footing beneath the Caissons to help prevent continued settling of the stack over time. To do this, undercut the soil beneath the bottom Caisson only wide and deep enough to tightly slip in a 4”X8”X16” concrete block. Move to the opposite side of the Caisson and place another block there. Repeat this block placement at the sides at 90 degrees from these first two.

Small Mining Bar

Hand Scoop

Small Hand Pick

Hammer & Masonry Chisel

Small Bucket

Pointing Trowel

Figure 40

Campus Development Series: Book One 49 With these first four blocks in place continue undercutting the Caisson and setting the block footings one block at a time until the entire circumference has been supported. If done properly there should be no additional sinking of the stack as the undercutting is done. Once the footing is in place and the Intake Chamber is filled with gravel the installation of the casing using the Alternate Method is complete.

Additional Materials & Tools Used For Alternate Method:

Materials Unit Price Quantity Total Qy. Price

Small Mining Bar 1 ea.

Hand Scoop 1 ea.

Small Hand Pick 1 ea.

Small Bucket 1 ea.

Masonry / Stone Chisel 1 ea.

Additional Block & Tackle 1 ea.

30’ Hardware Cloth in 4’ width 30 ft

¾” X 4’ X 8’ Plywood Sheet 3ea.

2” X 4” X 8’ Framing Stud 2 ea.

Duct Tape / preferably Gorilla Tape™ 100 ft.

Pea Gravel – 5 cu ft (1/4 ton) ¼ ton

4”X8”X16” concrete block 10 ea.

Water 600 Gal

Note that the Water Table has not been reached in the excavation process before sinking the Caisson stack into the Intake Chamber when using the Alternate Method, so there is no water accessible from the well for pre-casting the Caissons or mixing mortar for the ferrocement casing. Therefore, the entire amount of 1500 gallons of water used for this masonry work must be transported to the worksite.

Biologically

Active

Top Soil

Aquifer

Zone

Loose

Packed Sand

and Gravel

Water

Table

Fill the Bottom

3’ of the Intake

Chamber With

Firmly

Compacted

Medium Sized

Gravel

Figure 41

Figure 42 Footing Blocks

Compacted

Sand, Clay,

Gravel, &

Stone

Campus Development Series: Book One 50

APPENDIX A: Manufactured Tools.

Slip Form: The Slip Form is fairly simple to construct and requires only 1 ea. sheet of 1/8” X 2’ X 3’ metal, 2 ea. 1 ½” X 1 ½” X 22” wooden spacers, 6 ea. screws, and perhaps to use some Gorilla Glue™ to fasten the spacers to the back side of the metal in addition to the screws. The main challenge is that the metal must be bent to a perfect 22 ½” radius from top to bottom. This is done by plotting an arc of this radius onto plywood and carefully bending the sheet metal to fit the shape.

Well Shaft Support System: This is discussed on pages 11 – 12. Precast Form Inner Wall Support Rings: Detailed on pages 32 – 33.

Block & Tackle: Since it is possible that the Block & Tackle will be used to lower the Caisson rings with the Alternate Method, and that there will need to be two of these tools available, it is advantageous to manufacture both of these at the same time and build them so that they can be easily rigged to operate with a 4:1 mechanical advantage, having 4 ea. movable pullies in the system. But since it is also desirable to use a 3:1 mechanical advantage for lifting the lighter loads of soil and masonry mixes for the ferrocement casing casting it is still easy to rig these for that operation by fixing the rope to the forth pulley in the system rather than to the fixed block – similar to the set-up in Figure 6 on page 8 – so that there are actually only 3 ea. movable pullies in the system. The Block & Tackle are constructed mainly from plywood and have six basic parts; The wooden blocks: The Pullies: 3/8” bolts for the pulley axels: 3/8” “allthread” stretchers with hex nuts for frame supports: The rope: And metal hooks for load lifting.

Campus Development Series: Book One 51

Start by laminating 2 ea. of the Vertical Blocks together with Gorilla Glue™ to make up the total of 12 ea. Vertical Blocks at 1 ½” thick. Center the allthread stretcher rod through the lower hole in 4 ea. of the Vertical Blocks, using a small dab of Gorilla Glue™ on the threads at that center point and fastening this in place with 2 ea. Hex Nuts. Thread two more Hex Nuts onto the ends of the allthread so that two more of the Vertical Blocks can be slipped on at the proper spacing. Fasten the first layer of Top Block to the Vertical Boards using Gorilla Glue™ and screws as shown at the right. Fasten the second Top Block in a similar fashion. Thread on the outer Hex Nuts and tighten these down to secure the proper spacing. Install the ½” allthread in the Top Blocks. Install the pulley wheels using 3/8” washers as spacers on both sides of each wheel to prevent friction. Note that all of the Hex Nuts need to be set with Gorilla Glue™ to prevent loosening. Use the allthread spacer to fix the end of the rope to in order to set this up with a 4:1 Mechanical Advantage.

Basket: The Basket, made from ¾” plywood, is also simple to construct. The most complex aspect of this is fitting and fastening the beveled joints. The only pieces necessary are two ends, two sides, the bottom, strips of ¾” X ¾” plywood to serve as corner blocks, and the ¼” ropes fastened at the corners. The acute angle of the bevel is 760. This is easy to lay out and cut on the ends and sides. However, it is necessary to set the circular saw to this angle to cut the sides of the bottom and also the bottom support strips. Use Gorilla Glue™ on all of the joints.

24 ea

Vertical Blocks

16 ea. 3” Diameter

discs @ ½” thick

28 ea. 3/8”

Hex Nuts 8 ea. 1” Diameter

Discs @ ¾” Thick

4 ea. Pieces of ½”

“Allthread” @

12” Long with 8

ea. ½” Hex Nuts

4 ea. 3/8” Bolts @ 9” Long

4 ea. 3/8” “Allthread” @ 9” Long

4”

5 ½”

8 ea. Top Blocks

8 ¼”

4”

Campus Development Series: Book One 52

Bosun’s Seat: The simplest way to construct a Bosun’s Seat is to laminate a 1 ½” thick board @ 12” X 16” from plywood and suspend this from its center-point with ¾” rope.

1’

1’ 16”

18” 22”

2 ea. Ends 2 ea. Sides 1 ea. Bottom Cut To Fit

Inside the Box On Top

of the Bottom Supports.

The corners will also need

to be notched out to fit

around the corner blocks.

Use the square cut

strips on the side

edges of the ends as

corner blocks.

Use the bevel cut strips on the bottom edges

of the ends and sides as the bottom

supports.

The side pieces will butt

squarely to the end

pieces. Notice also that

the screws are driven in

at an angle to help

prevent stripping out.

Detail of the bottom joint.

Campus Development Series: Book One 53

Caisson Sling: The Caisson Sling is simply two boards used as spacers to keep the ropes pulling up vertically, and a set of rebar hooks.

APPENDIX B: Measurements & Calculations.

Balance Arm Scale for Measuring Weights: The proportions for the dry ingredients used in the Ferrocement Mortar, the Pervious Concrete, and the Bentonite / Cement Grout Slurry mixtures are measured by weight, not volume, so it is necessary to have some method for measuring these quantities. A Balance Arm Scale provides a good method of doing this, and the apparatus is easy to set up. Although this is technically a manufactured tool, it is much more an application of scientific principle and mathematical calculation, so it discussed here rather than in Appendix A. There are two main categories of Balance Arm Scales; the equal arm balance, and the unequal arm balance: and further, there are two types of unequal arm balances that are of interest here.

Equal Arm Balance Scales

By far, the most recognizable style of Balance Arm Scale is the Equal Arm Balance. This is a simple device where the Standard Weight and the Unknown Weight are suspended from the Balance Arm at equal distances, A and B, from the pivot point. In order to determine the weight of the Unknown on the right side of the scale, standard weights are added to the left side of the scale until a perfect balance is obtained, indicated by the pointer that aligns with the vertical center-line below the pivot point. When this balance is achieved the Unknown Weight is equal to the amount of Standard Weight added to the system.

Campus Development Series: Book One 54

Unequal Arm Balance - Steelyard Scales[27]

A steelyard has a beam with unequal arms. The load / Unknown Weight is suspended from the short arm of the beam. The Standard Weight is suspended from the long arm and is moved until equilibrium is obtained. This style of Unequal Arm Balance is used to measure loads that are equal to or heavier than the Standard Balance.

Unequal Arm Balance - Bismar Scales A Bismar has a Standard Weight fixed permanently to one end of the beam. The load / Unknown Weight is fixed to the other end. The pivot is moved along the beam until equilibrium is obtained. The ratio of the respective distances of the Standard and the Unknown from the pivot point becomes a factor which, when multiplied times the Standard, will return the value of the weight of the Unknown. For example, at the right the pivot is about ¼ of the way from the Standard to the Unknown. If a load became balanced with the pivot point in this position, then the weight of the Unknown would be 0.25 X Standard Weight.

Variation of the Steelyard:

The drawing on the next page shows a variation of the Steelyard Scale that can be applied when measuring Unknown Weights that are less than the Standard Weight and also those that are heavier than the Standard. The difference between these two operations depends on which weight is fixed to the short arm and which is movable.

As mentioned above, loads that are heavier than the Standard are fixed to the short arm, and the Standard is movable along the long arm. To explain this principle of “Torque” simply, if the Unknown Weight in the bucket balances when the Standard is set at the 1x position, then these two weights are equal, and there is a 1:1 ratio between them. However, if the balance is obtained with the Standard at the 2x position, then the Unknown is twice as heavy as the Standard (2:1) ratio. Likewise, if the beam balances with the Standard is positioned at 2.5x (2.5:1 ratio), then multiply the Standard by 2.5 to find the weight of the Unknown. . . . . Suppose the Standard is 10 lbs and it balances with the Unknown when in the 3.66x position. Then the Unknown Weight is 3.66 X 10 lb = 36.66 lbs.

27 International Society of Antique Scale Collectors, “Scale Types,” ISAAC Website Via, http://www.isasc.org/Tutorial/Scale-Types.html.

(Accessed May 14, 2015)

Illustrations Via: “Scale Types”

International Society of Antique

Scale Collectors –ISAAC- Website

http://www.isasc.org/Tutorial/Scale

-Types.html

Campus Development Series: Book One 55

Note that the weights of the containers used to hold the Standard Weight and also the Unknown Weight become factors in these equations since they are not actually the quantities being measured. However, in the case of the application here, the weights being measured are relatively large compared to the weights of the containers used, which will probably be 5 gallon buckets. Therefore, the differences in the proportional weights of the containers as the system is adjusted will be relatively negligible compared to the much larger measured quantities. Also consider that water provides a very reliable Standard Weight to use in this system: i.e., water weighs 8.346 lbs / gallon or 41.73 lbs / 5 gallons.

Volume Measurements: Ferrocement Casing, Annular Space / Seal, and Caisson wall volumes:

The Casing and Caissons are basic hollow cylinders. Calculations to determine the volume of these structures is a matter of subtracting the volume of a smaller solid cylinder from that of a larger cylinder, but it is possible to skip a step by first calculating the cross-sectional surface areas of the respective cylinders and then subtracting the area of the smaller disc from the larger. The resulting surface area is then multiplied by the height of the cylinder to find its volume. But to find the surface areas and volumes of the features of this Hand Dug Well the following calculations are made; Volume of the Annular Space: The outside diameter of the Well Shaft is 4’ (48”) and the Radius is 2’ (24”). The formula for calculating surface area of a disc is: Pi (π = 3.1415) X Radius2 = Surface Area. Therefore, the surface area of a 4’ disc is π X 2’2 = 12.56637 ft2. Next, find the surface area of the disc defined by the inside diameter of the Annular Space. Since the Annular Space is 1 ½” thick all around the circumference, the diameter of the inner disc is 48” – [2 X 1 ½” = 3”] = 45”, which is 3.75’, and the Radius is 1.875’. The surface area of this disc is π X 1.875’2 or π X 3.5156 ft2 = 11.0466 ft2. So the cross-sectional surface area of the Annular Space is 12.56637 ft2 – 11.0466 ft2 = 1.51977 ft2. Since there are two possibilities for how high the Annular Space will be depending on whether or not the Alternate Method is used, it is best to find the volume per foot of height value, then multiply this times the actual height required to find the total

Conversely, when the Standard is fixed to the short arm and the Unknown Weight is movable, then weights that are equal to or less than the Standard are being measured. In this case the Standard Weight is divided by the proportional distance of the Unknown’s position from the pivot point. For example, if the Standard is 10 lbs and the Unknown balances at the 2.5x position, then the Unknown Weight is: 10 lbs / 2.5 = 4 lbs.

Diameter of

Smaller Disc

Diameter of

Larger Disc

The difference is the cross-sectional

surface area of the hollow cylinder

Campus Development Series: Book One 56 volume of the Annular Space. And of course, for one foot of height the volume will be 1.51977 cu ft. If the Annular Space is a full 20’ from the base of the casing to the Annular Seal, then the Annular Space volume will be 30.3954 cu ft. If it is only 5’, as indicated with the Alternate Method, then the total volume will be 7.59885 cu ft.

Volume of the Annular Seal: Since the Annular Seal is a foot larger in the radius its total outside diameter is 6’, and the radius is 3’. So the surface area of the larger disc in this case is π X 9 ft2 = 28.27433 ft2. The inside diameter will be the same as for the inside of the Annular Space, which is a radius of 1.875’. The surface area of this disc is 11.0466 ft2. The difference in these surface areas is 17.2277 ft2, and the volume of the Seal at a depth of about 4 ½’ is 77.5247 cu ft. Note that this is calculated for the Seal as it is about 10” below ground level beneath the Apron. Volume of the Apron: The Apron extends out 3’ from the outside of the casing, so it will have an outside diameter of 10’ and radius of 5’. The surface area of this disc is π X 25’2 = 78.5398 ft2. Again, it’s inside diameter and radius will be the same as the Annular Space and Seal @ 11.0466 ft2. So the surface area of the Apron is 78.5398 ft2 – 11.0466 ft2 = 67.4932 ft2. At a depth of 10” or 0.83333’ the volume of the Apron will be 56.2443 cu ft. Volume of the Ferrocement Casing: The outside diameter of the casing is a total of 3” less than the 4’ diameter of the excavated Shaft Wall, accounting for the 1 ½” Annular Space. This is 45” or 3.75’, and the radius is 1.875’. As calculated above, the surface area of this disc is 11.0466 ft2. The inside diameter of the casing is 6” less than this @ 39” or 3.25’, and the radius is 1.625’. This surface area is π X 2.6406 ft2 = 8.29577 ft2. The difference between these surface areas is 2.7508 ft2. The volume of the casing at the full 25’ depth from the Water Table is 68.77 cu ft. At the 10’ depth with the Alternate Method this volume will be 27.50 cu ft. Volume of the Caissons: The outside diameter of the Caissons is 3’ and with a 2 ½” wall the inside diameter is 31” or 2.5833’. The surface area of the larger disc is 7.0686 ft2, and that of the inside disc is 5.2547 ft2, so that the difference is 1.8139 ft2. At 18” or 1 1/2’ deep the volume of the Caissons is 2.7208 cu ft. Rebar and Hardware Cloth for the Armature: The volumes of these materials seem comparatively small compared to the masonry products. However, in the larger structure they constitute a significant portion of the overall volume and must be know in order to accurately calculate the amounts of the masonry ingredients that will be used. It is also may seem a bit disproportional to calculate these volumes in terms of cu ft. However, since the volumes of all of the other materials are figured in these quantities it is advantageous to have the volume values for the iron available in cu ft also. Volume of the #3 – 3/8” Rebar: The diameter of the rebar is 0.375”, which is 0.03125’. This figures out to be a cross-sectional surface area of 0.00076699 ft2. Multiplied by a factor of 1’ this becomes the volume of the rebar in cu ft per lineal foot. Multiply this value by the total lineal feet of rebar in a particular depth of structure to calculate the total volume of the rebar. For example, The Caissons contain 4 ea. 60” pcs plus 5 ea 16” pcs of rebar for a total of 320” or 26.666 lineal feet of rebar. The volume of this rebar is 26.666 lineal ft X 0.00076699 cu ft / lineal foot = 0.02045 cu ft. For the total 20’ stack of Caissons this is about half a cubic foot of rebar.

Campus Development Series: Book One 57 Volume of the Hardware Cloth: In a similar manner, the volume of the Hardware Cloth is figured in a quantity per square foot of mesh. At 1/8” diameter of the cross-section of the wire the radius is 0.0625”, which is 0.005208 ‘. This is a surface area of 0.00008522 ft2. To calculate the volume of material per square foot of Mesh it is necessary to know how many lineal feet of the wire is in this area. In this case, a Mesh of 2” squares has been called for. Therefore, there will be 6 ea. wires in a one foot square in both dimensions, for a total of 12 lineal feet of wire. 12 lineal feet X 0.000008522 ft2 = 0.001022653 cu ft / square foot of Mesh.

Basic Materials Data: Water Weight / cu ft = 62.428 lbs / cu ft Water Weight / gallon = 8.346 lbs / gallon Water gallons / cu ft = 7.48 gal / cu ft Protland Cement: 94 lbs / cu ft Sand: 103.7 lbs / cu ft

Sodium Bentonite: 69 lbs / cu ft Gravel: 95 lbs / cu ft Fluid Concrete: 150 lbs / cu ft #3 Rebar: 0.38 lbs / lineal foot

APPENDIX C: Well Construction Records. Constructing a Hand Dug Well is an experience that should be devoted to a journal record. It is a group effort that takes a period of several days of coordinated teamwork to complete. Not only does such a journal preserve the social and educational aspects of the event, but also important technical data that can be referenced at a later time may be kept in the journal. For example, daily entries should include data pertaining to the following;

Names of workers at the worksite: A record of any accidents: A record of any visitors to the worksite: Climatic conditions such as temperature, rainfall, etc.: An accounting of the delivery of materials to the site: Details of concrete mixes and quantities involved: and a Description of work, including depth of well excavated.

The journal should also provide a record of information for maintenance and the construction of future wells. As mentioned early in this booklet, the digging of this well provides a “test pit” for determining the soil conditions for other constructions at the Campus site. Therefore, an important notation is a record of the strata through which the well has been sunk. Other important details include; The level and depth of Aquifer Zone: The depth and nature of any rock encountered: The actual finished length of lining and caissons: Top and bottom levels of the permeable section of the shaft: Whether water enters through the side and/or bottom: Thickness of gravel lining at the bottom of the well: The Static head – the pump down head – and the recovery rate of the well: and any other such pertinent data that will significantly affect the maintenance and operation of the well. Pages at the end of this booklet provide space to make these and other pertinent notations.

Campus Development Series: Book One 58

Summary

Campus Development Series: Book One 59

Works Cited

Abbott, Stephen P., Hand Dug Wells: Choice of Technology and Construction Manual,

Via, https://www.google.com/url?url=https://www.oxfam.org.uk/equipment/catalogue/resources-included-available/water-and-

sanitation/well-digging/handdugwell-BOOK.pdf/at_download/file&rct=j&frm=1&q=&esrc=s&sa=U&ei=yaZLVYKQJ8vWoASK34H4DQ&ved=0CDYQFjAH&us

g=AFQjCNHU0MxQwJTr3-Nhbj7VZ3M432ngnA. (Accessed May 6, 2015)

Also Found Via,

http://www.sswm.info/sites/default/files/reference_attachments/ABBOT%204000%20Hand%20Dug%20Well%20Manual.pdf. (Accessed May 6, 2015)

Alden, Andrew - Geology Expert, “ Cement and Concrete,” (About Education Website,)

http://geology.about.com/od/mineral_resources/a/cement.htm. (Accessed April 20, 2015)

Ban, Cheah Chee, Mahyuddin Ramli, “Optimization of Mix Proportion of High Performance Mortar for Structural Applications,”

(Penang, Malaysia: Sustainable Housing Research Unit, School of Housing, Building and Planning, University Sains Malaysia,

American J. of Engineering and Applied Sciences 3 (4): 643-649, 2010.) Via: http://www.google.com/url?url=http://www.researchgate.net/profile/Chee_Cheah/publication/49619589_Optimization_of_Mix_

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A-Well.html. Video URL, https://www.youtube.com/watch?feature=player_embedded&v=PXqg5yiCvhg. (Accessed May 4, 2015)

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