Document 524 PRELIMINARY DESIGN REPORT CHAPTER: EWB...

Document 524 - Preliminary Design Report Rev. 09-2011

EWB-CCNY

Milla Tres, Honduras

Water Distribution in Milla Tres

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Document 524

PRELIMINARY DESIGN REPORT

CHAPTER: EWB-CCNY (http://www.ccny-ewb.org/)

COUNTRY: HONDURAS

COMMUNITY: MILLA TRES

PROJECT: WATER DISTRIBUTION IN MILLA TRES

PREPARED BY

Liza Billings, Benjamin Conable, Liam Byrne,

Rachel Lovell, Tristan Schwartzman, Eric Ilijevich

Michael Piasecki, PhD, Stephen Morse, PE

Submittal Date: April 15, 2012

ENGINEERS WITHOUT BORDERS-USA

www.ewb-usa.org

http://www.ccny-ewb.org/

http://www.ewb-usa.org/


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Table of Contents

Preliminary Design Report Part 1 – Administrative Information ........................................... 4

1. CONTACT INFORMATION ....................................................................................................... 4

2. Travel History ................................................................................................................................ 4

3. Project Discipline(s): ..................................................................................................................... 5

4. Project Location ............................................................................................................................. 5

Preliminary Design Report Part 2 – Technical Information .................................................... 6

5. INTRODUCTION ......................................................................................................................... 6

6. PROGRAM BACKGROUND ...................................................................................................... 7

7. FACILITY DESIGN ..................................................................................................................... 8

1. Description of the Facilities ...................................................................................................................... 8 2. Description of Design and Design Calculations ..................................................................................... 12 3. Drawings ................................................................................................................................................. 22

8. PROJECT OWNERSHIP ............................................................................................................ 29

9. CONSTRUCTABILITY ............................................................................................................. 29

10. OPERATION AND MAINTENANCE .................................................................................... 34

11. SUSTAINABILITY .................................................................................................................. 35

12. COMMUNITY AGREEMENT/CONTRACT .......................................................................... 36

13. COST ESTIMATE .................................................................................................................... 38

14. PROFESSIONAL MENTOR/TECHNICAL LEAD ASSESSMENT ...................................... 41

1. Professional Mentor/Technical Lead Name (Michael Piasecki, PhD) .................................................... 41 2. Professional Mentor/Technical Lead Assessment .................................................................................. 41 3. Professional Mentor/Technical Lead Affirmation .................................................................................. 42 4. Professional Mentor/Technical Lead Name (Stephen Morse, PE) ......................................................... 42 5. Professional Mentor/Technical Lead Assessment .................................................................................. 42 6. Professional Mentor/Technical Lead Affirmation .................................................................................. 43

15. REFERENCES .......................................................................................................................... 43

Table of Tables Table 1: Summary of Minor Head Loss Coefficient Values ....................................................................... 18 Table 2: Pipe Sizes with Calculated Velocities and Flow Rates ................................................................. 20 Table 3: Material Specification Transportation Labor ................................................................................ 32 Table 4: Construction Labor not including EWB team members ............................................................... 33 Table 5: Preliminary Labor Estimate, Conduction Line ............................................................................. 34 Table 6: Dam Materials and Constructions Costs Preliminary Estimate .................................................... 38 Table 7: Preliminary Conduction Line Costing Table ................................................................................ 39 Table 8: Preliminary Tank Materials Costing Table ................................................................................... 40 Table 9: Typical Chapter Travel Budget for 7 students, 1 advisor ............................................................. 41


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Table of Figures Figure 1: Dam Site Looking West - Wet Season Flow ................................................................................. 8 Figure 2: Path of Conduction Line from Source to Tank.............................................................................. 9 Figure 3: Tank and Location Schematic ..................................................................................................... 11 Figure 4: Rational Method Flow Calculations ............................................................................................ 14 Figure 5: Calculations - Shear in Foot ........................................................................................................ 15 Figure 6: Calculations - Moment in Foot .................................................................................................... 15 Figure 7: Contour Map with Pipe Path ...................................................................................................... 16 Figure 8: Elevation Changes Based on Contour Map Overlay, Conduction Line ...................................... 16 Figure 9: Milla Tres Impoundment Watershed ........................................................................................... 22 Figure 10: Milla Tres Water Impoundment - Dam Site Elevation .............................................................. 23 Figure 11: Milla Tres Impoundment - Plan View (NTS) ............................................................................ 23 Figure 12: Milla Tres Impoundment - Elevation (NTS) ............................................................................. 23 Figure 13: Milla Tres Impoundment - Section A-A (ref. Figure 12) (NTS) ............................................... 24 Figure 14: Section A-A (ref. Figure 12) for Impoundment Overtopping Analysis (NTS) ......................... 24 Figure 15: (a) Section B-B (ref. Figure 14) (b) Qualitative Moment (NTS) .............................................. 25

Figure 16: Shear and Moment Analysis Diamgram (Foot) (NTS) ............................................................. 25 Figure 17: Moment Analysis Diagram (Dam Face) (NTS) ........................................................................ 26 Figure 18: Preliminary Valve and Connection Details ............................................................................... 26 Figure 19: Preliminary Trenching Details (NTS) ....................................................................................... 27 Figure 20: Preliminary Anchorage Details, and Map of Likely Support Locations ................................... 27 Figure 21: Eventual Tank Condition - New Tank and Existing Tank in Parallel (NTS) ............................ 28 Figure 22: Signed Agreement Between EWB-CCNY and Milla Tres........................................................ 37


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Preliminary Design Report Part 1 – Administrative

Information

1. CONTACT INFORMATION

Name Email Phone Chap. or Org.

Name

Project Leads Liza Billings [email protected] 917-439-9161 CCNY

President Tristan

Schwartzman

[email protected] 347-981-2980 CCNY

Mentor #1 Michael Piasecki [email protected] 610-564-8184 CCNY

Mentor #2 Stephen Morse, PE [email protected] 917-273-8236 NYC

Health and Safety

Officer

Liza Billings [email protected] 917-439-9161 CCNY

Assistant Health

and Safety Officer

Sarah Martinez [email protected] 347-301-6513 CCNY

Education Lead Sarah Martinez [email protected] 347-301-6513 CCNY

NGO/Community

Contact

Alex Uriel del Cid [email protected] 011-504-2665-

0440

Municipalida d

Omoa, Honduras

2. TRAVEL HISTORY

Dates of Travel Assessment or

Implementation

Description of Trip

January 2012 Assessment Did community assessment and technical assessment for Milla

Tres potable water system. Found the project to be feasible, and

established agreement with the community.

August 2011 Assessment Did community assessment and technical assessment. Found

Tegucigalpita project to be not feasible or necessary.

August 2010 Implementation Implemented ventilation project in the community of La Nueva

Suiza. Did post-implementation assessments on prior projects in

Las Chicas and La Nueva Suiza

Jan 6-23 2009 Implementation Implemented work on water systems in Las Chicas, including

building latrines, water basin, water tank lids, a chlorinator,

replaced piping, installed values and grey water management

system.

Jan 2008 Implementation Nueva Suiza-building water tank lid and chlorinator

Aug 16-26 2008 Assessment Assessment trip for Las Chicas, Tegucigalpita and Nueva Suiza

ventilation project.

Jan 2007 Implementation Nueva Suiza-Building water tank and distribution system.


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3. PROJECT DISCIPLINE(S):

Water Supply

_x__ Source Development

_x__ Water Storage

_x__ Water Distribution

_x__ Water Treatment

____ Water Pump

Sanitation

____ Latrine

____ Gray Water System

____ Black Water System

Structures

____ Bridge

____ Building

Civil Works

____ Roads

____ Drainage

_x__ Dams

Energy

____ Fuel

____ Electricity

Agriculture

____ Irrigation Pump

____ Irrigation Line

____ Water Storage

____ Soil Improvement

____ Fish Farm

____ Crop Processing Equipment

Information Systems

____ Computer Service

4. PROJECT LOCATION

Longitude: 90 degrees 27 minutes 0.346 seconds West

Latitude: 4 degrees 47 minutes 18.311 seconds North


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Preliminary Design Report Part 2 – Technical Information

5. INTRODUCTION

During the chapter’s trip to Honduras for an assessment in Tegucigalpita in August 2011, the

team consulted with the municipal mayor and engineer. The municipal engineer took the to a

number of sites for advice and to encourage the chapter to do work in these communities in the

future. During these trips, it seemed that the implementation process that championed by the

municipality for each project was very similar to that of Engineers Without Borders, particularly

with respect to a three-spoke collaboration between the community, the engineers, and funding

agencies or sponsors. However, the municipality does not have sufficient resources to implement

all of the projects that are required. The chapter explained the process of applying for a project

with EWB, and the municipality expressed interest in pursuing this option. Within a month of the

team’s return to New York, the municipality and community of Milla Tres, a town which had

visited and where it was concluded that a project within the chapter’s capacity, provided the

information necessary for a project application and an initial assessment.

The EWB-CCNY chapter returned to Honduras in January, 2012, for a formal assessment of the

community. Milla Tres is a town of approximately 1050 people living in fewer than 150 homes.

Initially, the town had a limited but effective water distribution system. The system piped water

from a spring source to a tank, and then from the tank to a central location in the community. At

some point, a distribution network was introduced, so that every home has a tap. Three years ago,

a small magnitude earthquake disrupted the source, such that it no longer provides sufficient

water. Currently, the community water system functions at two levels: residents of approximately

45 homes at higher elevations use the disrupted source, with a resulting deficit of water in the dry

season. Homes located at lower elevations (approximately 90) are serviced by a secondary

source. The immediate need is for the homes at higher elevations to be served by a reliable

source, including growth for this portion of the community, with a future possibility for the lower

elevation homes to tap into the new system. The community has identified a new water source

that is productive enough to serve both areas of the town, including growth; however, they don’t

have the technical or financial resources to design and implement the system without assistance.

The community has taken a number of small-scale actions in an attempt to address this problem,

but has done so without technical advice and without success. In particular, they built a new tank

at a higher elevation in the hopes that this increased elevation would lead to increased flow. Their

effort demonstrates both their commitment to solving the problem and their need for technical

assistance in completing the project. The terrain between the new source and the community has

been assessed, and a technical design is being developed for the project, of which this report is a

portion. Additionally, a training plan is being developed for system maintenance.

The EWB-USA CCNY Chapter project in Milla Tres consists of the design and construction of a

new water system, from source to tank. The project will comprise a water impoundment at a pool


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below a consistent and sufficient spring source, a transmission line from the impoundment, and a

storage tank and treatment system sufficient for 20 years of growth in the community.

As we are a student chapter with a high member turnover rate, we are constantly mindful of

future members who will be coming in with less knowledge and experience. As a part of the

effort to provide chapter continuity, we are making an effort to produce a clear project

development and implementation template that future members will be able to use. In addition to

being a project that fits well with our capabilities as a chapter, a project such as the one in Milla

Tres should provide the framework for future work for our members.

6. PROGRAM BACKGROUND

The EWB-CCNY Student Chapter has had a presence in the Omoa region of Honduras since the

chapter started in 2005, completing 3 projects in 2 different villages, as well as doing an

assessment for a third project that resulted in finding the project to not be feasible. The current

members of our chapter feel that it would be beneficial to continue with similar projects in the

region, as we can effectively use the connections we have already established and learn from the

data and information already collected. In this light, the chapter has decided to continue with a

water-focused project in Milla Tres, Honduras.

The assessment trip to Milla Tres in January, 2012 included a community health survey and

alternatives analysis, which reinforced the importance of a new water system for community

health and quality of life.

Alternatives analysis was conducted for the Milla Tres water system for the following

parameters:

System Type

Possible Sources

Water Management at Source

Tank Location

Pipe Route

Conduit Materials

Dam Materials

Tank Materials

Treatment and Filtration Options

A gravity driven system has been determined to be the best option, conducting water from a

dammed reservoir slightly below the chosen spring to a new tank, in series with the old tank, via a

conduction line. Both the dam and the tank will likely be constructed with reinforced concrete,

while the conduction line will likely be designed primarily as a PVC conduit, with sections of

more durable steel or cast iron where necessary. Given the desire of the community to follow a


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particular pipe route that is feasible with regard to elevation changes, it is determined that

selection of that path is the best option. Water quality management options are still being assessed

but will likely include chlorine treatment at the tank as mandated by Honduran regulations, and

could include a settlement box or gravel filter at the impoundment for reduction of particulate

matter.

7. FACILITY DESIGN

1. Description of the Facilities Dam

The dam site is at the downstream mouth of a small natural pool. The pool is approximately 25

feet across and is cut from living rock. It contains one large boulder (>2000 lbs) and substantial

gravels and small boulders of unknown quantity. Estimates from assessment team members are a

few cubic yards or less of loose material in the pool basin.

Figure : Dam Site Looking West - Wet Season Flow

The site drains a natural spring with measured flows of 500 gpm in the wet season, May to

November, and 300 gpm in the dry season, December to April. The site also drains a 148 acre

watershed of mountain forest with no habitation and no agriculture (Figure 9, Drawings section

3.3). The furthest point in the watershed is less than one (1) km from the dam site in the east-

southeast direction. This area of the tropics may see extreme rain events and peak flows at the site

may be as high as 17,000 gpm for extended 1 in/hr rainfall as estimated using the rational method

(see Calculations). Rainfall above 1 in/hr would produce larger flows possibly up to twice the

high estimate. Such flows are expected to be of short duration after rainfall due to the small

watershed and steep terrain drained at the site.


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The stream mouth to be dammed is 4’-6” at the base and 12’-0” at the top, approximately 4’-0”

above the base of the pool (Figure 10, Drawings section 3.3). Both sides of the dam site are living

rock of semi-weathered condition. SSW of the dam site within ten (10) feet is a natural spillway

approximately 3’-0” above the floor of the pool. Building the dam to the full four (4) foot height

of the abutting rock will activate the natural spillway and protect the dam from all but peak flows.

The proposed design is for a cast in place concrete dam of one (1) foot thickness and four (4) foot

height in a simplified arch design. A filtered water collection port near the base of the dam will

provide constant head from the open reservoir to the water transmission line leading to the

storage tank above Milla Tres.

Conduction Line

The pipeline connecting the source impoundment to the storage tank will run between 2 and 2.5

km over mountainous terrain. The path from the source to the tank site was selected by the town

as being reasonably direct, lacking severe and sudden elevation changes, and covering land that

they are able to access. Given the community confidence that this is the best route, and the

experience of the chapter that finding another route whose elevation never exceeds the source

would be difficult, it was determined to be the best path option. Figure 2 shows the route from the

source impoundment location to the location of the tank.

Figure : Path of Conduction Line from Source to Tank

According to waypoints recorded with a Garmin GPSMap® 78 Series Track, the difference in

elevation between the two points is approximately 15 meters. There is some question related to


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the accuracy of this measurement, as dense tree cover can affect the accuracy of readings, and a

contour map of the same route shows an approximate 100 meter elevation change, as detailed in

the Description of Design section of this report.

Based on an evaluation of alternatives, it was determined that the primary piping material will be

PVC, due primarily to ease of accruement, cost, and comfort level of the community. While

materials other than PVC have higher durabilites and therefore would require less maintenance,

the capability of the community to make repairs when required is dramatically lowered, because

of both tool availability, and cost of parts. Where required, galvanized iron (GI) piping will be

used, for example, in locations with direct UV exposure where trenching is not possible, in areas

with high person or livestock traffic where trenching is not possible, and over long spans, where

high relative ductility of material is of greater detriment than weight.

Given the length of the conduction line, and breadth of possible implementation obstacles and

situations, the final design will encompass standard details for the following elements, at

minimum:

Thrust block details, including typical construction details and situations requiring use

Staking details for steep grade, including maximum conditions between stakes and

installation requirements

Support structure requirements for ravine crossings, including bracing elements and

maximum unsupported span lengths for both pipe materials

Typical joinery details for both material types, including straight and angled connections

Typical valving details for both material types, including a schematic of anticipated

check, air release and gate valve locations, based on expected elevation changes and

pipeline geometry

Trenching details, including depth and drainage

Many of these details are outlined in the Description of Design section of this report (Section

3.2), and some preliminary figures are provided in the Drawings section (3.3).

Tank

The existing tank, approximate capacity of 3750 gallons, was determined to be inadequately sized

to meet anticipated future demand considering expected community growth and the additional

service load of houses from the lower elevation community, but adequate for the existing homes

in the upper town. Part of the chapter commitment includes providing facilities with the capacity

to meet peak water demand for at least twenty years, providing safe, treated water for the town

and being structurally sufficient to operate over this period of time. In order to ensure a successful

implementation that is within the capacity of the chapter and the town to execute, and given the

design team’s desire to obtain additional data regarding bedrock locations at the new tank site and

additional testing for water quality to determine best treatment methods, the conduction line will


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run to the existing tank. The new tank and treatment system will encompass a future

implementation, and will be built inline with the existing tank, offering some redundancy to the

system in the case of maintenance or other unforeseen issues.

A reinforced concrete tank with a volume between 7250 gallons will be designed and built for the

town of Milla Tres in a future implementation. The tank will consist of a reinforced cylindrical

curtain wall on top of a reinforced concrete slab. Figure 3 below provides a general schematic of

the site and the tank.

Figure : Tank and Location Schematic

The site located for the new tank is approximately 1200 ft south of and 170 ft higher than existing

tank, which is in turn approximately 200 ft south of and 60 ft higher than the closest residence.

The main factors that go into the design of the tank are the stability of the soil, crack control and

adequate steel reinforcement for bending and hoop stresses. Due to the location next to steep

grades, as shown in Figure 3 above, the slab and its support will need to be properly designed in

order to prevent any failure due to slope instability. The slab will be modeled as a square matt

footing and the possibility of anchoring the footing, due to the steep surrounding grades, is being

discussed. Other issues with the slab that need to be addressed are the possibility of hydraulic

uplift and cracking due to excessive settling.

The method of building the curtain wall is still under review. Three reinforced options are under

consideration; cast in place concrete, CMUs or masonry brick, in order of preference. Masonry

construction with a cast in place lid is typical for the region. The chapter design team prefers cast

in place concrete for all components due to its superior strength and stability. The community has

many skilled construction workers with experience in all three types of construction.


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The cap of the tank will be reinforced concrete cast in place. There will be an access hatch on the

cap with a metal rung ladder imbedded in the curtain wall to allow access to the interior of the

tank for repair and cleaning.

Either a drip feed chlorinator or a tablet chlorination system will provide disinfection. It is

believed that the tablet chlorinator would be easier to operate and maintain within the existing

community water budget. The availability of tablets to the community, and the comfort level of

community members responsible for maintenance with the tablet system, are still being evaluated.

There is a drip chlorination system on the existing tank that is unused. The chapter will attempt to

initiate its use with the implementation of the new source and conduction line through community

education and through operations and maintenance plan development. Assessment between the

first phase implementation and the tank implementation will further guide chapter and community

discussion regarding effective disinfection regimes.

2. Description of Design and Design Calculations Dam

Figure 11 (Drawings section 3.3) shows the plan view of the proposed impoundment. A

simplified arch design provides strength and stability by transmitting the force of the water acting

on the dam into the abutting living rock walls of the dam site. This abutment supported dam

design allows for significant material savings over gravity dam designs, an important

consideration given that all materials must be hand carried to the site over more than two

kilometers of rugged terrain. Steel reinforcement in the dam section protects against concrete

failure in tension and due to impacts against the dam from solid objects in storm condition flows.

The dam will have an elevation even with the top of the southeast abutment. When the pool fills,

it will not overtop the dam but will rather limit at the height of a natural spillway southeast of the

dam (Figures 12&13, Drawings section 3.3) This spillway will protect the top edge of the dam

from wear due to constant flow and will capture debris away from the water intake site. The

spillway location is directly opposite and in the path of the flow entering the impounded pool.

This suggests that during heavy storm flows, the majority of the energy and debris in the flow

will be directed at the spillway rather than at the dam. Nonetheless, efforts have been taken in the

dam design to account for overtopping and impacts at the dam.

28 day concrete strength of 2500 psi will be expected from the concrete mix (yet to be designed).

Concrete strength is sufficiently low to be placed without additional strength testing being

required by EWB-USA and is a reasonable value for carefully field-mixed concrete. Reinforcing

steel yield strength was assumed to be 40,000 psi. Should 60,000 psi steel be available, steel

reinforcement may be reduced based on similar calculations to those followed below.

The dam section will include a foot cast into a channel cut into the rock of the site to a width of

six (6) inches and a depth of three (3) inches (Figure 13, Drawings section 3.3). This embedded


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foot will provide strength against slipping downstream by bearing on the rock of the foot

channel’s downstream face. The foot will anchor the dam in the site. This method is familiar to

the local partners participating in the dam construction.

Steel reinforcement design in the dam was undertaken based on methods found in ACI 318-11

Building Code Requirements for Structural Concrete (ACI, 2011) and in Design of Concrete

Structures (Arthur H. Nilson, 2010). The method includes considering the dam as a slab made up

of adjacent one (1) foot thick beams. The beams are designed under the heaviest loading that any

of the beams endures and all points are designed to that standard. This analysis is very

conservative, as adjacent areas of concrete cast monolithically provide significant support to the

“beam” under consideration.

Analysis was carried out for four design considerations, shear and moment at the foot of the dam,

and shear and moment in the central span of the dam. Loading for analysis was taken at estimated

extreme flood conditions wherein the spillway’s ability to handle flow has been overwhelmed and

flow one (1) foot deep is moving over the dam. The dynamic load of the flow is approximated by

doubling the static load of the water, pooled to a depth of one (1) foot above the dam height

(Figure 14, Drawings section 3.3).

Shear in the Foot

Shear in the foot and moment in the upstream face were analyzed using a one (1) foot by one (1)

foot cantilever beam identified in Figure 15(a) (Drawings section 3.3) with loading shown in

Figure 16 (Drawings section 3.3). In addition to doubling the static load under flood conditions, a

live load factor of 1.6 and a strength reduction factor of 0.75 were included. Further, for

unreinforced sections, an additional penalty of 0.5 was included. Calculations show that an

unreinforced foot of 6.0” thickness is sufficient to withstand the shear load applied to the beam by

the total depth of water without any of the loading distributed into the abutments. As loading will

distribute into the abutments and some reinforcing is required for moment considerations at the

foot, 6.0” will be ample support against shear failure at the foot.

Moment in the Foot

Reinforcement against moment in the foot was determined assuming fixity at the foot. This is a

highly conservative assumption, as the depth and bonding of the foot is not sufficient to develop

full fixity. Additionally, as with the shear design, adjacent concrete and the arch abutments

provide counteracting moment to that applied by the force of the water. Even without additional

support, minimum reinforcement as defined in ACI 318-11 10.5.1 is sufficient to prevent tensile

failure in the upstream beam face and provides a safety factor of 1.83 in addition to factor load

and strength reduction factors. Reinforcement required is #4 bars, placed vertically 6.0” on center

with 3.0” of concrete cover and extending down into the foot. It is recommended that a number of

bars (4-6) along the central span be epoxy set into drilled holes in the rock below the foot to a

depth of 12.0”. This additional material at the dam – rock interface will further improve strength

contra shear failure and sliding downstream.


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Shear in the Dam Face

Maximum shear for the dam face “beam” is below the minimum for shear reinforcement and is

therefore not required.

Moment in the Dam Face

Finally, reinforcement in the downstream side of the dam was designed assuming the most

heavily loaded one (1) foot section of the central six (6) foot span of the dam was taken as a

simply supported beam (Figures 14&17, Drawings section 3.3) This is a very conservative

assumption as we see in Figure 15(b) (Drawings section 3.3) that forces normal to the side panels

of the dam provide counteracting moment which reduces the maximum moment in the section.

Using minimum reinforcement, though this time on the total thickness of the dam rather than just

the foot, there is sufficient strength to withstand the full load at the bottom of the dam. This

minimum reinforcement carried throughout the height of the dam will provide strength against

impacts at the top of the dam, where loads due to flows are light, but impacts due to objects in the

flow are possible. It is important to note again that the path of objects in the flow is not directly

downhill and into the dam. The stream at the far upstream end of the pool enters the pool mostly

down and toward the spillway. Objects moving with the flow would likely bounce off the bottom

of the pool and then be carried at below flow velocity in the direction of the flow. Consideration

of impacts on the dam is a precaution rather than an expected condition. Horizontal reinforcement

of #5 bars, 6.0” on center and extending the breadth of the dam will provide a 3.53 margin of

safety in addition to load factors and strength reduction factors.

Calculations:

Figure : Rational Method Flow Calculations


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Figure : Calculations - Shear in Foot

Figure : Calculations - Moment in Foot


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Conduction Line

Figure : Contour Map with Pipe Path

The color-graded contour map shown in

Figure 7 and the corresponding elevation

change map shown in Figure 8 can be taken as

indicative of the terrain, assuming relatively

constant tree cover. For the purposes of

design, the more conservative value of 15

meters obtained from waypoint data is used,

despite the appearance from the contour maps

that the elevation change is approximately 100

meters. An inline globe valve for flow

adjustment is included in the design up-line

from the tank, should the flow from the pipe

due to increased head be far larger than is

reasonable given the tank capacity.

Given the experience of chapter members

walking the conduction line path, the severe

changes in elevation shown at approximately

0.25 km from the source in Figure 8 are taken as outlier recordings, and the high point shown at

approximately 0.1 km should be taken as the source location. From the figure, it is apparent that

approximately 5-6 air release vales should be used, at the high points in the line. It is also noted

that a clinometer will be used during the implementation of the project for flagging the exact pipe

path while assuring that the elevation of the pipe never exceeds that of the source, as is prudent

for a gravity fed system.

Figure : Elevation Changes Based on Contour Map Overlay, Conduction Line


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As a first step in determining pipe sizing, the elevation difference between source and the tank

was taken to be 15 meters. Taking into account a conservative horizontal distance of 2500 meters,

by triangulation the minimum distance between the source and the reservoir was calculated as

√ meters. However, as the topography changes frequently between the

source and tank locations with elevation changes and curves, an estimate of a third more than the

minimum distance between two points was used for calculation, In feet, the estimated

pipe length 10,936.33 ft, and the elevation difference is 49.21 ft.

To obtain different flow quantities through pipe, the energy equation is used between two points

of interest (Hwang, 1996).

(

)

(

)

(Eq.1)

Where:

p: Pressure (psf)

: Specific weight (pcf)

z: Elevation (ft)

v: Velocity (ft/s)

g: Acceleration due to gravity (32.2 ft/s2)

hl,minor: minor head loss due to change in pipe geometry

hl,major: major head loss due to friction in the pipe.

As both source and reservoir are open to the atmosphere, the pressure at both points can be

approximated as zero (0) psf and difference in elevation between two points has already been

calculated as 49.21 feet. Moreover, the water level at the source can be approximated to remain

constant, leading to an approximation of velocity as close to zero (0) at the source. Equation 1

then simplifies to:

(Eq.2)

Minor head loss occurs as a result of changes in geometry. The general form of minor head loss is

given by:

(Eq.3)

Where

k: minor head loss coefficient, varying with each type of geometric change


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One (1) pipe will run from the source to the tank, therefore one (1) entrance and one (1) exit are

considered for minor headloss. The connection of the pipe at the source is assumed to be perfectly

straight with head loss coefficient of 0.5. Minor head loss coefficient the exit is 1 (Hwang, 1996).

As it is impossible to determine the number of joints required along a pipeline of this length with

certainty, values deemed reasonable were assumed. As typical commercial pipe is available in

20ft (6.1 meter) lengths, there will be at least 556 joints to connect all pipe ends. To account for

uncertainty and assuming that many pipes will be cut one or more times to fit to the terrain, it was

decided that calculation will be done with total of 900 joints (allowance of one additional

cut/joint for every other pipe length). Joints will include straight joints, 45° elbows and 90°

elbows. Typically, straight joints have almost no head loss if two pipes are connected well. 90°

elbows have higher coefficient of head loss than 45° elbows, by a factor of approximately two

(2). It is assumed based on the topography that most of the joints in the conduction line will be

45° elbows. Given this assumption, all 900 joints are assumed for calculation purposes to be 45°

elbows, with the number of 90° bends actually installed anticipated to be far less than the number

of straight connections, the balance of which results in a conservative calculation.

Minor head loss due to valves was also considered. At this stage of design, the exact number of

valves is unclear. It was decided that total of 15 check valves will be used for the calculations. Air

release valves do not have designated head loss coefficient, but the k value for T-type connection

can be used as good estimation. A total of 10 air release valves will be taken into consideration

during the calculation, greater than the anticipated need of six (6). Six (6) gate valves and two (2)

globe valves for flow shut-off and control are also allowed for. Table 1 summarizes the total

minor head loss due to all the components contributing to the minor head loss.

Table : Summary of Minor Head Loss Coefficient Values

Component Coefficient Total component Total loss

Entrance 0.5 1 0.5

Exit 1 1 1

45 degrees bent 0.4 900 360

Check valve 2.5 15 37.5

Air release valve 0.3 10 3

Gate Valve 0.18 6 1.08

Globe Valve 7.8 2 15.6

Total 418.68

Although coefficient values change with varying pipe diameter (typically displaying reverse

proportionality), for ease of iteration in selection of pipe diameter, the most conservative value is

used. For example, the head loss coefficient for a 45° elbow is 0.4 for a ¾” diameter pipe. The

value for a 4” diameter pipe is 0.27, but 0.4 is used for all minor head loss calculations.


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Major head loss in a pipeline is caused by friction between the pipe surface and water flowing

through the pipe. According to the Darcy Weisbach equation (Hwang, 1996), major head loss

can be described mathematically as:

(

) (

) (Eq.4)

Where

f: major head loss coefficient

L: length of the pipe (ft)

V: flow velocity (ft/s)

D: pipe diameter (ft)

For given pipe material, and assuming that flow in the pipe is neither laminar nor extremely

turbulent, the friction coefficient can be estimated using the Colebrook equation.

√ (

√ ) (Eq.5)

Where

e: roughness coefficient of the pipe (ft)

NR: Reynold’s number

The roughness coefficient of standard PVC pipe is ft (Hwang, 1996). The two

terms in the parentheses account for variations in ‘hydraulic smoothness’ behaviors, where the

first term considers the relative roughness of the pipe, and the second term considers the pipe

flow that exhibits enough of a laminar sub-layer to act as ‘hydraulically smooth’, or unaffected by

pipe roughness. NR, Reynold’s number, given as Equation 6, is a function of the mean fluid

velocity, V, the hydraulic diameter, DH, and the kinematic viscosity, ν.

(Eq.6)

For circular pipe, the hydraulic diameter is equal to the interior pipe diameter. For water at

standard conditions, the kinematic viscosity is 1.08 x 10-5

ft2/s (Hwang, 1996). Equation (5)

above can be iterated to solve for the pipe friction coefficient for varying pipe diameters, and

hence can be used in Equation 3 to find the major head loss along the conduction line. Given the

anticipated prevalence of PVC as the piping material of choice and conservative assumptions

elsewhere in headloss calculations, it is assumed that the increase in major headloss effects from

any sections of galvanized iron (GI) piping, are absorbed into the calculation safety, and major

headloss is calculated under the assumption that the entire pipeline is constructed of PVC.


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If a value is assumed for the friction coefficient f, Equations 2, 3, & 4 can be evaluated for a

given pipe diameter and known pipe length to solve for velocity, via Equations 7 & 8:

( (

) ) (Eq.7)

√

(

)

(Eq.8)

Having obtained a value for velocity, Reynold’s number can be calculated via Equation 6, and a

corresponding value of f can be calculated via Equation 5. If the value calculated for f varies from

that assumed by more than the accepted error, the calculated value for f is assumed and used in

the subsequent iteration. For these calculations, acceptable relative error is set as 0.10%

calculated as:

|

| (Eq.9)

After calculating the velocity of the water, the volumetric flow rate of the water can be calculated

by taking the product of the velocity and the cross sectional area of the pipe.

(Eq.10)

Where

Q: volumetric flow rate (L/s)

Table : Pipe Sizes with Calculated Velocities and Flow Rates

Diameter (inches) Velocity (ft/s) Flow rate (L/s)

2 1.210 0.7475

2.5 1.363 1.317

3 1.492 2.074

4 1.693 4.184

Given a desired minimum velocity of approximately 1.5 ft/s and a peak demand estimated at 3.3

L/s (refer to Tank Design Description section), it is likely that a 3” or 4” pipe diameter will be

selected for the final design. Additionally, the final design will include detailed recommendations

for pipe supports at steep slopes, joints, and ravine crossings. Some preliminary notes are

included in Figures 19 & 20 (Drawings section 3.3).


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Tank

A potable water storage tank provides a supply of safe, clean drinking water near to town. It is the

vessel in which disinfection occurs and may provide a certain amount of backup supply should

problems occur in the conduction line between the source and the town. This suggests that there

are two important considerations when sizing a tank, disinfectant residence time and emergency

supply. Both are a function of throughput and therefore a function of peak demand.

The municipality estimated a 4.5% annual growth rate for Milla Tres. That is more than double

both the five year averaged growth rate for Honduras of 2.0% and the 20-year averaged growth

rate of 2.2%. According to World Bank data, Honduras has not had population growth above the

1962 high of 3.33%. Taking the 20-year averaged growth rate and including both the upper and

lower town (135 houses), the expected town size for the village in 20 years as determined from

the exponential growth equation is:

(Eq.11)

With an average of seven (7) persons per household, the population in 20 years is expected to be

1463 people. Water use per capita per day is estimated to be 70 L for drinking, washing and

bathing. This is deemed sufficient from observed water use in the town and documentation for

water distribution systems in the area. Using a factor of 1.4 to account for a peak day demand the

maximum daily demand in twenty years is:

(Eq.12)

Assuming that all the water demand occurs within 12 hours of the day:

(Eq.13)

The minimum flow-rate at the source, about 19 L/s, is more than adequate for the peak demand of

3.3 L/s. This 3.3 L/s rate equates to a total peak flow tank capacity of 3.5 hours for an assumed

combined tank capacity of 11,000 gallons. The existing tank and demand yield a peak flow tank

capacity for the houses located at the higher elevation of:

(

) (Eq.14)

However, with no method for identifying when flow is interrupted to the tank, the amount of

emergency water is irrelevant. If cessation of service is the first time anyone knows there is a

problem, it means the emergency capacity is already gone. Conversely, with warning, even 3.5

hours of peak flow water is more than enough for a day of restricted service. Full tanks provide


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about 28 liters per person for the estimated 20 year growth population. This suggests that

identifying loss of flow to the tank is a priority in the tank implementation phase.

The chlorination treatment system needs to be selected in order to ensure proper dwell time and a

proper uniform concentration. Contact time above 20 minutes is deemed sufficient for

disinfection at proper chlorine residual levels. This contact time is easily achieved with the

discussed tank sizes at more than twice the expected peak flow.

The drip chlorinator needs to be calibrated properly to ensure a consistent amount of chlorine is

dripped into the water. The tablet chlorinator is attached to the in-feed just prior to the tank. The

tablets can be changed out easily, the exposure to water is constant and will not cause any spikes

in concentration. It will cut down on any added construction complexities that more arise from

mounting a drip system to the top of the tank. For these reasons the tablet system is being

considered.

Soil collected from the site was analyzed to determine the stability. The conclusion under the

Unified Soil Classification System (USCS) is that the soil is poorly graded sand with less than

15% gravel. This may be a factor in the stability of the soil and geotechnical expertise is being

sought in regards to this issue. Refer to Drawings section 3.3.

3. Drawings Dam

Figure : Milla Tres Impoundment Watershed


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Figure : Milla Tres Water Impoundment - Dam Site Elevation

Figure : Milla Tres Impoundment - Plan View (NTS)

Figure : Milla Tres Impoundment - Elevation (NTS)


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Figure : Milla Tres Impoundment - Section A-A (ref. Figure 12) (NTS)

Figure : Section A-A (ref. Figure 12) for Impoundment Overtopping Analysis (NTS)


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Figure : (a) Section B-B (ref. Figure 14) (b) Qualitative Moment (NTS)

Figure : Shear and Moment Analysis Diagram (Foot) (NTS)


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Figure : Moment Analysis Diagram (Dam Face) (NTS)

Pipeline

Figure : Preliminary Valve and Connection Details


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Figure : Preliminary Trenching Details (NTS)

Figure : Preliminary Anchorage Details, and Map of Likely Support Locations


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Tank

Figure : Eventual Tank Condition - New Tank and Existing Tank in Parallel (NTS)


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8. PROJECT OWNERSHIP

In Honduras, each community has a water board that is responsible for collecting a small tax from

the community for maintenance and repair of the water distribution system, and for making sure

that the system is kept working. In the community of Milla Tres, this ‘junta de agua’ is currently

led by Nicholas Cruz. A new board is elected each year in the community to ensure the continued

integrity of the board. All operational responsibilities for the water distribution system fall on this

board.

The chapter worked closely with the full board throughout the assessment process. The board was

engaged and supportive of the project, and expressed a full commitment to assisting in the project

during the implementation phase, and taking full ownership of the project into the future.

All facilities of the water distribution system will be located on publically owned land. Currently,

the site of the proposed storage tank is on privately owned land. However, the community has

come to an oral agreement that the land will be granted to the community. A written contract will

be provided in advance of construction of the storage tank.

9. CONSTRUCTABILITY

Implementation of the final design must be feasible. A number of factors must be considered in

determining this feasibility. The construction will take place in Milla Tres, Honduras. Therefore,

all required materials must be available regionally. Required construction equipment must also be

available, either directly through the community or with the help of the district government. The

community must also have the capacity for the use of this equipment. Construction schedule,

including transportation of materials, is also of concern, as all complex work needs to happen

under chapter supervision. Finally, construction requires moderate weather, as the dam site drains

a small watershed and flows there can be large for short durations. Access to dam and conduction

line may be inhibited by strong rains.

The new tank construction will not be part of the August, 2012 implementation trip and therefore

none of the constructability issues related to it will be discussed here. However, the tank is the

most standardized of the components of the new system. Tanks of the type considered exist in

many communities in Honduras, including the small, existing tank in Milla Tres. With the further

site analysis performed during the trip, no special problems regarding the tank are expected to

arise, given the tank sites proximity to town, the ease of access, and the availability of materials.

Role of the Chapter

EWB_USA CCNY Chapter members will act as construction managers for the construction of

the dam, the conduction line and the tank hookup. Additionally, they will participate in


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subsurface exploration of the new tank location, existing tank condition evaluation and repair,

and restoration of chlorine disinfection to the existing tank. The Chapter will communicate labor

and pre-implementation trip schedule to the community and confirm community preparations

with regard to material purchase and movement.

Role of the Community

Community members will provide skilled and unskilled construction and material transportation

labor before and during implementation. A specific schedule has not yet been developed, but

Chapter estimates suggest that the project will require 15 - 20 total workers during the

implementation trip and 5 – 10 workers for a week prior to the implementation trip. Improved

estimates will be developed in the next phase of planning and in consultation with the

community. The community includes many skilled construction workers who will lead the

construction of the system under the supervision of travel team members. The travel team is

cognizant of the construction expertise within the community and will ensure conformity with the

engineered plan while deferring to the community in all matters in which they are expert

including but not limited to material transportation in the area, working with draft animals, and

construction methods and processes.

Schedule

With the long cure times of concrete construction, the need for Chapter members to conduct

testing on completed system components and collect data from which to finalize the Operations

and Maintenance plan, the Chapter is considering splitting the implementation trip into two,

staggered trips of regular 10 day duration but with fewer Chapter members in each trip. The

Chapter has more than enough members and sufficient mentors to staff two staggered trips.

Details regarding expected transport and construction times for each system component are

outlined below. Final decision regarding one trip or two staggered trips will be made prior to

TAC review.

No specific schedule has yet been completed, but in general, the dam and all other concrete work

will commence immediately upon first team arrival in expectation of system testing toward the

end of the second team’s trip. In order to facilitate this tight schedule, the Chapter is negotiating

with the community to purchase and stage materials prior to the arrival of the first team. Planning

is underway to ensure that mission critical pre-trip schedule items are completed and verified with

the Chapter.

Material Availability

The dam and some support foundations for the conduction line will be constructed of reinforced

concrete. The conduction line will be made of PVC and galvanized iron pipe with appropriate

fittings and valves. All of these materials are available locally, based on August, 2011 soundings

by Chapter Mentor, Stephen Morse. Certain materials related to the temporary coffer dam and

conduction line will come with the Chapter team or be specially sourced as discussed below. The

tools required to construct the project components are available locally, including a concrete


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mixer, which the community verified was available for rent from a local hardware store. The

Chapter is bringing a gas-powered concrete and stone saw to cut in the toe of the dam. Horses and

donkeys are available within the town to help with material transport.

Dam

Material for the dam construction must be taken to the site, or prepared at the site, prior to the

travel team’s arrival. These materials include fine aggregate, purchased and transported to the

site, and coarse aggregate, screened from the gravel pools at and below the site. Rebar and lumber

should also be moved to a safe location near the site and protected from weather with tarps. There

is little or no danger of theft at the dam site, due to its location high in the mountain jungle, far

from any habitation other than Milla Tres.

The first phase of the project is the construction of the cofferdam to divert the water to a higher

elevation spillway adjacent to the dam location. The materials to be used for the cofferdam

include large plastic bags to be purchased in the U.S. and brought to Honduras with the travel

team. The bags are to be filled with aggregate from the site and the larger pool downhill from the

site. An alternative method is outlined below, which utilizes a large water bladder. The advantage

is speed and ease of installation, the disadvantage is the water bladder’s large size and expense.

Coffer Dam Option 1 – Water Bladder Dam

This is the most time efficient and easiest way to build the coffer dam. The device consists of an

inflatable rubberized material, which is filled with water and then uses the weight of this water to

resist and block the flow of the stream. Its installation requires about one extended day of work.

The installation is not labor intensive, as the majority of the work is done by the free flowing

water which will fill the bladder, using its weight and special straps to keep it docked in place. A

coffer dam built using this method needs to be at least one foot higher than the water level.

Assuming a water level of about three (3) feet, the water bladder dam would need to be four (4)

or more feet tall, including any berm upon which the bladder rests. There are several suppliers of

such products in the US, with their products slightly varying from each other, but utilizing the

same principles and concepts.

Coffer Dam Option 2 – Plastic Bags Dam

The coffer dam can also be built using plastic bags filled with some kind of aggregate easily

obtainable from the river bed. Assuming a dam of about 20 feet, and using a safety factor of 1.8

the material required for such a dam would be close to 5 cubic meters. Using 90-110 lbs bags,

which can easily be moved around by workers, 320 bags would be needed. Note that the number

of bags needed could be reduced, if stones or other heavy bulk materials were used to build part

of the dam. Assuming that half of the material can be obtained from locations close to the dam

site, and half of it from further away an average filling rate of 4 bags/person-hour is within

reasonable limits. That means that if 8-9 people were available to work, a ten hour working day

should be enough to build the coffer dam by this method. If the filler comes from more than 200

feet away, the time needed may increase to two days.


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To reduce the possibility of any flow through the wall of bags, a plastic sheet needs to be used.

The area covered by the plastic sheet will be approximately 15 square meters, with 6mm plastic is

placed in two layers to reduce the likelihood of through flow due to manufacturing defects.

Syphon

It is expected that some seepage will occur under the coffer dam, regardless of the method chosen

to build it. The flow due to this seepage will be moved off site by a siphon system consisting of a

PVC pipe or flexible hose with a length of about 30 feet. A two inch diameter pipe should be

enough to carry the flow, depending on the efficiency of the coffer dam.

Once the cofferdam is complete, a 3-inch deep, 6-inch wide channel will be cut as described in

the dam drawings using a concrete saw brought from the U.S. The formwork for the dam will be

assembled with lumber and nails. Lumber will be carried to the site before or during the

construction of the cofferdam. The materials to be used for the dam as well as required labor for

transporting them are listed in Table 1 and will be carried to the site before and during formwork

construction. The bags of Portland cement can be divided into smaller bags to make transport to

the site easier.

Table : Material Specification Transportation Labor

Material Specification Units Labor

Tools Various Various 1 person days

Wood Various 30 3 person days

Aggregate:

Coarse

1.5 cy of 1” clean

aggregate (collected near site) 1 person days

Gravel 5 cy (collected near site) 2 person days

Aggregate: Fine .5 cy well graded clean

sand 40 4 person days

Cement Portland Cement 10- 100# bags split into

~50# bags 3 person days

Rebar Not Yet Calculated 30-ft 2 person days

Water Uncontaminated water for

concrete mix (collected on site) NA

Food, Drinking

Water,

Miscellaneous

Various Various 4 person days

Total 20 person days


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Table : Construction Labor not including EWB team members

Material Labor

Site Preparation 2 person days

Coffer dam

Construction 4 person days

Form construction 4 person days

Pour 4 person days

Total 14 person days

The concrete will be mixed and placed by hand on site. The mold and cofferdam will be removed

at the judgment of the Junta de Agua and EWB-USA CCNY members not less than 7 days after

concrete placement (75% strength development) based on flow conditions and whether doing so

is deemed safe. Non-storm flow conditions are more than a factor of 2 reduced from design

conditions, and so are well within the 7 day strength of the dam.

Conduction Line

The path of the pipeline presents several challenges, as the terrain and accompanying conditions

change repeatedly over the approximately 2.5 km distance. Prior to arrival of the travel team,

community members will cut back vegetation along the pipeline path, allowing for increased ease

of movement for chapter members, materials staging, and labor. Upon arrival of the

implementation team, the exact route of the pipeline will be marked. As the terrain makes

transportation of survey equipment very difficult, and the heavy affects the accuracy of GPS

equipment, a clinometer will be used to approximate slope, assuming that the line does not rise

above the elevation of the source, and to determine required locations of air release and pressure

release valves.

Where possible, the pipeline will be trenched for protection from person and animal traffic, and

UV damage. Some areas exhibit steep grade, making trenching a hazard for slope stability. A

final design of stakes constructed to anchor the exposed pipeline to the hillside, and method for

UV protection of these sections (if constructed with PVC) will be provided prior to TAC review.

Where changes in pipe direction occur, particularly in portions of the pipeline that are exposed,

concrete thrust blocks or another effective anchoring technique must be used to prevent excess

movement that could cause joints to loosen.

As it is impossible to determine with accuracy the number of each type of obstacle or condition

along a pipeline of this length, the final design will provided typical details of strategies for

dealing with any expected installation condition. Table 5 presents a preliminary labor time


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estimate for conduction line construction. It should be noted that allowances for trenching and

exposed conditions are assumed.

Table : Preliminary Labor Estimate, Conduction Line

Task

Est. Time

(person-

day) Equipment/Tools

Development of Access 4 Machetes, shovels

Marking Pipeline 3 flags, level

Connection at Dam 0.5 drill, mallet, piping

Connection at Tank 0.5 drill, mallet, piping

Trenching to ~16" (allowance of 1.5

km distance) 8 shovels

Stake-Driving at mountain-side

(allowance of 1 km distance) 5 sledgehammer, staking materials

Laying of Pipe, including all

connections and valve installs 8 piping, connections, valves, tape, glue, saw

Installation of 'thrust blocks' 6 wood for forms, cement, aggregate, water

Materials Transport (throughout

construction) 5

Sum 40

10. OPERATION AND MAINTENANCE

Required maintenance of the facilities should be within the skills of the community and should

not include components that are unavailable or difficult to use/install. EWB-CCNY will create a

master document written in Spanish and English that will describe and illustrate the water system

from source impoundment to tank. This document will be given to the leader of the local water

board, Nicholas Cruz. It will include descriptions, definitions, illustrations, maps, maintenance

instructions and procedures, troubleshooting guide, and a materials list. The final document will

likely contain some combination of descriptive diagrams and photos of as-built conditions for

clarity. As such, sections of the O&M manual for each system element will be completed and

delivered after implementation of the facility. As the tank will be constructed on a later

implementation trip, the manual will be updated at its completion. A preliminary bulleted list of

items to be included in the manual follows:

Dam:

Inspect dam, clean filter and remove pool debris weekly

Note dam site conditions and water turbidity

Complete log book entry for each weekly inspection

Cut back vegetation biannually


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Conduction Line:

Pipe route walk of exposed sections weekly, and as soon after significant storms as

possible, with repairs as necessary

Weekly stake and ravine crossing structural support inspection section, with repairs as

necessary

Map of all valve locations, types, and replacement costs

Instructive diagrams for valve replacement and typical joinery

Complete log book entry for each weekly inspection, and note all repairs occurring at this

time or otherwise

Tank:

Inspect and replenish tank treatment system operation as required, dependent on final

design of treatment system

Drain tank, remove sediment, scrub interior and clean filter every two weeks

Note tank conditions: tank cracking, leaking, surrounding soil erosion, influent and

effluent pipe and valve inspection for cracking, leaks, or deterioration.

Repointing of mortar joints annually or as needed, especially after seismic activity

Complete log book entry for each inspection, and note all repairs occurring at this time or

otherwise

11. SUSTAINABILITY

The project will be sustained through ongoing maintenance by the Junta de Agua and community

members. EWB-CCNY is a recognized community partner in this area, having worked on several

projects over the last 5 years with neighboring communities on lasting water and ventilation

projects. Keeping with this tradition, EWB-CCNY is nurturing a relationship with the community

of Milla Tres. The group spent a significant amount of time with community members during the

assessment trip in January 2012. The chapter members spent extensive time discussing the

proposed system with the leader of the local water board, Nicholas Cruz. The travel team was

able discern his understanding of the water distribution system, water treatment, dam and

retention tank, and learn how they maintain the current system. This helped to inform the

chapter’s design of a training, maintenance and education program that will ensure the

sustainability of the installed system. Mr. Cruz, has signed an official agreement between EWB-

CCNY and Milla Tres stating that they will provide manual labor, basic materials and tools, and

that they will maintain the system after it is completed.

Currently, the Junta de Agua collects 20 Lempira (~$1) monthly from each household in Milla

Tres, which is used to pay for the operation and maintenance of the system. The estimated O&M

costs per month of the new system are dependent on the final design. Completion of the

anticipated O&M requirements should be feasible within the framework of current community


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contributions. A more thorough analysis follows in the design completion report, including

review of maintenance costs for similar completed projects.

EWB-CCNY will create a manual written in Spanish and English that will describe and illustrate

the potable water distribution system. This document will be given to the local water board. It

will include descriptions, definitions, illustrations, maps, maintenance instructions and

procedures, troubleshooting, and a materials list.

EWB-CCNY will conduct an information/training seminar with Nicholas Cruz and the other

members of the water board. This will include a classroom-style information session followed by

a site inspection/demonstration. EWB-CCNY will also conduct a community-wide

information/education session in order to inform the residents about the newly installed system.

This session will include information about the necessity and function of the chlorine water

treatment component of the new system, about the importance and need to adopt recommended

water conservation measures and proper usage practices.

The EWB-CCNY team is committed to providing the community the necessary tools and

information needed to understand, to operate, to maintain and sustain their potable water

treatment and distribution system. Through these efforts, the newly installed system will be

sustained for many years to come.

12. COMMUNITY AGREEMENT/CONTRACT

The EWB-CCNY Chapter made a formal agreement with the community of Milla Tres in order to

establish and define the roles of both the community and the EWB team. By signing the

document the community agreed to contribute with manual labor and basic materials, such as

sand and gravel, during the construction of the system. Additionally, they have agreed to develop

methods for maintaining the new water distribution system. In return the EWB-CCNY chapter

agreed to develop a new water system, to include a dam at the source, a water tank and a

connecting conduction line.

In advance of traveling to Honduras to implement the project in August of 2012, this chapter will

send a copy of the design plan to the community for confirmation of the contract. Construction

will begin with a signed reaffirmation of the mutual commitment of EWB-CCNY and the Milla

Tres water board.


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Figure : Signed Agreement Between EWB-CCNY and Milla Tres


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13. COST ESTIMATE

Best estimates of project cost from the current stage of the design are presented here. Tables 6, 7,

& 8 present estimated costs for each facility, while Table 9 presents a the most recent travel

budget for a team of seven (7) students and one (1) advisor. After a more thorough analysis of the

best approach to travel in August 2012, the anticipated budget will more accurately reflect travel

costs dependent on team size and trip duration.

Prior to TAC review, the chapter will provide a detailed project budget, including amended

expected costs and available funds for a thorough assessment of the financial feasibility of the

project.

Table : Dam Materials and Constructions Costs Preliminary Estimate

EWB Milla Tres Dam - Form 524 Cost Estimate (Trip: 08/2012)

Coffer Dam: Option 1. SF 1.5 for transport

Materials Specification Units Cost/Unit

Aqua Dam 3'H x 7'W 25' $28.00/ft with 3 @ $40 collars

PVC Pipe Siphon System 4 $2.12/30 ft. Pipe

Option 2 backup as below 1 $530

$1,772.00

Coffer Dam: Option 2. SF: 1.5


Plastic Bag Heavy Duty 4 $75.00/bundle (100 bags = 1 bundle)

Plastic Sheet 6mm , 2 Layers 1 $45.00/15 sq. meters

PVC Pipe Siphon System 4 $2.12/30 ft. Pipe

Total: $530

Dam ~ 2cyd. SF: 1.5


Aggregate: Coarse 1" clean 1.4 cyd (collected on site)

Aggregate: Fine Fine clean sand .5 cyd $16/m^3

Cement Portland Cement 10 bags $5.09/100lb. Bag

Rebar

Not Yet

Calculated

$-----/30 ft. $100 est.

Water Uncontaminated 10 cft (collected on site)

Wood 1" x 12" x 14' 20 $11.02/pc.

Total: $567.00

Total (USD): $1000 - $2375


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Table : Preliminary Conduction Line Costing Table

Item Description/Use Unit Qty

C/U

(Lempiras) Sum

Galv. Iron Sleeve, 3" diam

for use where durability

requirements are not met

by PVC

c/u 8 115 920

45 deg. Elbow, Galv. Iron, 3" diam c/u 8 240 1920

90 deg. Elbow, Galv. Iron, 3" diam c/u 2 170 340

Galv. Iron Pipe, SCH40 (6m), 3"

diam

(6m

length) 20 1825 36500

Pressure Rated Coupling, GI-PVC

for connection between

pipe materials c/u 6 n/a

PVC RD26 (rated 160psi) (6m), 3"

diam standard piping material. If

PVC is not 'flared',

additional unit cost for

couplings

(6m

length) 450 345 155250

45 deg. Elbow, PVC, 3" diam c/u 800 108 86400

90 deg. Elbow, PVC, 3" diam c/u 10 115 1150

Reducer from 3" to 1/2" diam, PVC T joints, with reducer and

air release valves, for high

points along pipe route

c/u 10 60 600

T-joint, PVC, 3" diam c/u 10 185 1850

Air Valve, 1/2" diam c/u 10 420 4200

Bronze Check Valve for flow management and

shut-off

c/u 15 565 8475

Bronze Gate Valve c/u 6 1620 9720

Bar

for installation of 'thrust

block' where necessary

c/u 10 490 4900

Portland Cement (bag) 2 133 266

Sand m^3 1 320 320

Gravel m^3 1 320 320

flags for marking pipe path

TBD

stakes for securing pipeline to

hillside, materials TBD

sleeves

blade

miscellaneous necessities,

or possible needs

c/u 10 19 190

saw c/u 0 135 0

PVC pipe glue (gallon) 2 620 1240

Teflon Tape (roll) 4 290 1160

Pipe Cutter (GI), 2-4" c/u 1 2450 2450

Sum in

Lempira 318171

**all listed quantities are estimates for preliminary pricing/budgeting only, and

not intended for purchase

Sum in US

Dollars 16745.84


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Table : Preliminary Tank Materials Costing Table

7,400 gal Water Tank

Material # Units Unit Cost Cost

HG elbows 2 x 90 1 $81.29 $81.29

HG Nipple 2 x 12 1 $116.25 $116.25

PBC Nipple 4 x 4 m R26 1 $170.32 $170.32

PVC elbows 4 x 90 potable 1 $170.00 $170.00

3” hg cup cover 1 $96.77 $96.77

HG nipple 3 x 1 m 1 $433.55 $433.55

1” PVC threaded adaptor 1 $6.88 $6.88

2” ball valve with smooth PVC adaptor 1 $240.00 $240.00

PVC nipple 1/2 x 1m 1 $5.59 $5.59

PVC elbow ½ “ x 90 degrees 1 $3.55 $3.55

PVC Adaptor M ½ “ 1 $2.97 $2.97

HG Pipe reducer bushing 1 1/2 x 1/4 1 $26.67 $26.67

½ “ Hg elbow 90 degrees 1 $9.38 $9.38

bronze spigot 1/2" 1 $65.27 $65.27

½ “ Italian bronze valve with door 1 $82.97 $82.97

Portland cement 122 $123.95 $15,121.90

Smooth rebar ¼ “ x 30 actual 63 $41.14 $2,591.82

galvanized rebar 3/8 “ x 30 56 $110.48 $6,186.88

red masonry brick 1776 $4.33 $7,690.08

1/8 “x4’x8’ sheet metal 1 $157.50 $157.50

Tie wire 19 $14.94 $283.86

Total (Lps.) $33,543.50

Total (US) $1,765.45


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Table : Typical Chapter Travel Budget for 7 students, 1 advisor

Direct Costs Total Budget

Travel

Airfare $4152

Gas $130

Rental Vehicle $1420

Misc. $0

Sub-Total $5702

Travel Logistics

Exit Fees/ Visas $320

Insurance $120

Sub-Total $440

Food & Lodging

Lodging $2072

Food & Beverage (Non-

alcoholic) $750

Sub-Total $2822

Project Materials &

Equipment (details needed)

Sub-Total $0

TOTAL $8964

14. PROFESSIONAL MENTOR/TECHNICAL LEAD ASSESSMENT

1. Professional Mentor/Technical Lead Name (Michael Piasecki,

PhD) Michael Piasecki, PhD

Associate Professor for Water Resources Engineering

2. Professional Mentor/Technical Lead Assessment The base for the preliminary design report was laid during the last trip to Milla Tres in January of

2012. The team discussed the need of a new system with municipality officials and local water

board members. Furthermore, the team discussed the process by which the source was selected

and the reasons why the current system is inadequate. These discussions clarified the viability of

the source and the eventual necessity of a new tank at a different location. In this regard the team


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(Tristan Schwartzman, Liza Billings, Eric Ilijevich, Rachel Lovell, Liam O’Byrne, Ashley

Kebreau, and Sarah Martinez) did a fine job elucidating additional and all relevant information to

make this assessment. No full assessment of alternative designs were carried out, however the

group discussed at length the selection of source, the need for a new tank, how to run the feeder

pipe from new source, to new tank location, and also using the old system as a backup that

remains integrated into the newer system. The selected source makes sense (it is the only

available source that has constant productivity throughout the seasons and sufficient volume to

sustain population growth for the next 10-20 yrs.

In developing a preliminary design report, the team worked closely with myself and a number of

other mentors and professors both within and outside of the City College of New York campus.

The analysis combined research with this advice to produce a cohesive and clear report that

demonstrates that the team is well on their way to developing an implementation plan that will

meet the standards of EWB-USA. The design team has responsibly concerned all of the facets of

the final water distribution project, and feasible plans are well on their way to finalization for

each of these facets. Additionally, the team has given sufficient thought to scheduling and

financial issues for this step in the process.

In depth research is currently underway to make sure that the project is financially sustainable

both during the construction and the maintenance phases of the project. The team is also very

attuned to the potential difficulties in implementing a water distribution project of this size within

the time frame that will be available to the team. To address this concern, the team is looking at a

number of possibilities, including delaying building the storage tank to a second trip and

staggering travel teams to increase the amount of time available for implementation. I am

confident that a clear and feasible schedule will be developed in advance of the trip.

3. Professional Mentor/Technical Lead Affirmation I have been engaged in this process from the beginning and also traveled with the team to

Honduras. Therefore, I have intricate knowledge of the situation at the locale. The group has been

very proactive in engaging me in the design process and as such I feel comfortable accepting

responsibility for the course the project is taking.

4. Professional Mentor/Technical Lead Name (Stephen Morse, PE) Professional Mentor – Stephen A. Morse, PE

VP of EWBNY Professional Chapter

5. Professional Mentor/Technical Lead Assessment This preliminary design document was prepared through collaboration of approximately 12-15

students over the course of a 3 month period with the oversight and advisement from myself and


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Professor Piasecki. Weekly progress meetings were held by the entire team with multiple break-

out sessions held weekly. Studies and research were conducted across multiple engineering,

planning, public health and economics disciplines and specifically included structural

engineering, hydraulics, watershed analysis, pipe flow, soil and rock stability and construction

costs and constructability analysis. Project management was performed by individual task leaders

responsible for smaller design teams. Individual task leaders perform internal QA before

presenting findings and recommendations to the broader team where ideas were critiqued and

peer-reviewed by the larger group, the project lead, and the professional and academic mentor.

6. Professional Mentor/Technical Lead Affirmation I hereby acknowledge my involvement in the preliminary design phase of this important project

as well as an understanding of the community, having traveled with CCNY to the North Shore

area of Honduras in Summer 2011. I accept professional responsibility for the course that the

project is taking.

15. REFERENCES

ACI. (2011). ACI 318-11 Building Code Requirements for Structural Concrete. Farmington Hills:

American Concrete Institute.

Arthur H. Nilson, D. D. (2010). Design of Concrete Structures, 14th ed. New York City: McGraw-Hill.

Fischer, G. (n.d.). Piping Systems. Retrieved March 18, 2012, from George Fischer Piping Systems:

www.harvel.com/pipepvc-sch40-80-dim.asp

Hwang, N. H. (1996). Funtamentals of Hydraulic Engineering Systems (3rd ed.). Prentiss Hall.

The Engineering Toolbox. (n.d.). The Engineering Toolbox. Retrieved March 18, 2012, from

www.engineeringtoolbox.com/surface-roughness-ventilation-ducts-d 209.html

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