COMPANY PROFILE

ABHAY OCEAN INDIA PVT LTD Established in 1998 at Mumbai, by Capt. Jagdish Khokhar an ex

Indian naval officer, having over 35 years experience in managing & executing wide variety of

projects in Marine/Offshore Construction Services.

ABHAY OCEAN INDIA PVT LTD is a Company which has acquired multi skill industry knowledge &

experience to have an extremely competitive & cost effective market presence.

We are a young and dynamic company with core skills established in the field of Marine / Offshore

construction services. We aim to provide innovative engineering construction solutions with

technical excellence and total commitment to our clients' needs with special emphasis on quality and

safety.

AbhayOcean India Pvt. Ltd. is a Mumbai

(India) based company engaged in Marine

engineering Projects such as Submarine

Pipelines, Marine Intakes/ Outfalls and

Dredging /Trenching etc. Some of the

Marine Outfall projects implemented by

AOIL are as fallows..

Project: Marine Outfall Dahej, Gujarat.

Client: PunjLloyds, New Delhi.

Description: The system consisted of a

20 tons Diffuser and submarine

C.S. Pipeline of 24” Diameter for Indian

Petrochemicals Ltd.

In Gujarat

b) Project: Effluent disposal Outfall,

Pondicherry.

Client: Pondicherry Distilleries.

Description : The system consisted of a

Diffuser and submarine HDPE

Pipeline of 8” Diameter and 1.2 Km.

Long at Pondicherry

c) Project: Effluent Disposal Outfall, Goa.

Client : ZuariAgrochemicals Ltd.

Description : The system consisted of a Diffuser and submarine HDPE

Pipeline Of 12” Diameter and 2 Km. Long.

d) Project : Effluent Disposal Outfall, Karwar.

Client : Ballarpur Industries Ltd.

Description: The system consisted of a Diffuser and submarine HDPE

Pipeline of 12” Diameter and 3.5 Km. Long.

Project Client: Gulf petro Chemialservice

Pipe Line of 1200 mm Diaas intake for Muscat Refibery.

Some of the recently completed prestigious jobs

a)AOIL has recently executed near shore Trenching for M/s Leighton India Ltd for Kochi

Refinery SPM & Pipeline 58 inches for crude transportation.approx550 Mtrs

b)AOIL was also involved and part completed trenching work for Indian Oil Offshore Project at

PARADIP -HALDIA CRUDE RECEIPT FACILITIES. For Iranian offsore

c)AOIL completed the Pipe Transportation work. For Lay Barge “ABOUZAR”

d) Cairn Energy-Provision & management of Dipper Dredger, marine equipment, etc., and

carrying-out 14 Kms. trenching & burial work for 24” submarine gas pipelines at Suvalipoint,

Suratin currents of upto5-6 Knots and tidal variations of upto8 meters, as a subcontractor to

Hyundai Heavy Industries (HHI). We also helped HHI for pipe pull.

e)ONGC-Dredging and trenching at Mindholariver in a current levels of 7 Knots, for SHBT

Pipeline on behalf of M/s HundaiHeavy Industries (HHI).

M/s De DongeHolding shall be keeping one of their Dipper Dredgers and two in number hopper

barges (value approx. USD 14.0 Million) in India, which we would be managing/operating and

carrying out dredging / trenching works.

DREDGING WORKS:

The equipment we have access:

· Dipper Dredger with LeibherrP 994

· Two nosself propelled Hopper barges 850 Cu M each.

· Trailer Suction Dredgers

· Cutter Suction Dredgers

PIPELAY WORK:

AOIL has Two Number Flat Top Work Barges (230ftX 60ftX14ft) along with Two 1800 BHP Tugs

for any Offshore work

These Barges are suitably modified for Pipe Line Pull or Pipe Lay mode to undertake work

AOIL has access to qualified & Experienced project Managers / Supervisors and

specialisedEquipment like heavy lift Barges to complete a project ON Time /ON Cost

2 BASIS OF THE PROPOSAL.

This Proposal has been prepared based on the documents made available by TEC by E-Mail.

The proposed 100 MLD sea water reverse osmosis desalination plant located in Nemmalivillage

on the east coast road, approximately 35 Km south of the town of Chennai requires 265 mldof

sea water from reliable source of water of consistent quality. The rejects having TDS of 67000

ppmfrom the SWRO plant is designed for 165 mld. The following were taken into consideration

for selection and design of sea water and intake facilities.

Scope of works includes the supply by

contractor of all material, machinery, plant

site, supervision, labour, safety personnel and

all expenses necessary for the installation,

testing & commissioning of the sea water

intake and the reject outfall system.

Moreover, the scope includes but it is not

limited to:

•The review of the contract documents

related to design and construction of sea

water intake and outfall system comprising of

offshore & onshore feildstudy reports, data

and related analysis, computer modelling

reports, design drawings etc.

•Review of the oceanographic survey data

enclosed in chapter-3, volume IIA, and it felt

necessary, carryout the survey of the area

offshore to verify the nature of the sea

bottom in order to confirm the results of the

boreholes and stratigraphicdata enclosed

with the tender and to find the correct means

for the marine works.

•Excavation of the appropriate trench in the

sea bottom as per design drawings with

appropriate and supply and receive the HDPE

pipes along with associated accessories

constituting the intake and the outfall.

•Backfilling of the trench, supply and

installation of the various sizes stones &

materials in the areas indicated in the

drawings enclosed with this tender

specification.

Supply, Welding, laying and connection of the high density polyethylene (HDPE) pipes in the

submarine trench in accordance with the specifications. Prefabrication and installation of

concrete blocks for the anchorage of the pipes.

Prefabrication & installation of the concrete blocks for the system towards protection against

trawling fishing & other possible causes of damage.

Fabrication & installation of the intake screen (head) at the extremity of the sea water intake

pipeline and connection of the pipeline with special expansion spool piece joint as indicated in

the drawing. Fabrication & installation of the reject outfall diffusers section & connection with

special expansion spool piece joint as indicated in the drawings.

Fabrication & installation of the expansion special spool pieces connecting the 1600 mm dia. and

the 1200 mm dia. Pipelines for intake & outfall system respectively with the structures at their

extremities onshore and offshore. The selection of spool pieces shall be done based on previous

experience of similar installation and the same shall be procured from a reputed manufacturer

after prior approval from client/consultant.

Supply & installation of all necessary flanges, pipes & structures for the completion of the system

in accordance with the drawings. Supply & installation of the necessary Navigational Aids like

buoy with red laternmarks to mark the position of the structures as per drawings.

The battery limit considered for commencement of the Marine Intake / Outfall Pipeline is the

termination point of pipeline on the Shore. TEC will provide a concrete inspection chamber for

this purpose. Only 2 nos. of Valves, one at the Battery limit and one at the diffuser assembly has

been included and no manhole is included in this Proposal. 3. Scope of Work: Scope of work,

Supply and services envisaged under this proposal is as fallows.

a)Scope of Services Alignment Survey for Marine Intake Outfall Pipeline. b) Proposed Pipeline

route and & Diffuser Intake Sructurelocation will be marked with the help Of DGPS. c) Bottom

topography –Bathometric Survey Depth contours covering an area 1 km on either side of the

proposed pipeline route d)Geotechsurveys with bore hole at every Two hundred meters on both

pipe lines roué. e)Design and Engineering Pipe lines designed & Engineering based upon surveys

i) HDPE Pipes 1600M. long ii) Diffuser Intake Structure Assembly and other attachment.

c) Scope of Work.

i)Supply & Preassembly of the Pipelines

ii) Dredging of Trench & Back fill BurrialInstallation of the Pipelines

iii) Insulation & Installation of the Diffuser System. / intake structure

iv) Testing.

v) Commissioning.

vi) Operation and Maintenance

4. PLANNING of SUBMARINE OUTFALL.

At the outset fallowing information will be obtained from available sources, Nautical charts,

bathymetric maps, oceanographic maps, SONAR charts and sounding, as bottom samples,

Meteorological records, oceanographic studies, reports of marine biology and any other

information available.

In planning a submarine outfall the first step should be to determine a suitable location for the

diffuser/ Intake Structure. The determination of the location and design of the diffuser for a

submarine Intake outfall would be based on obtaining adequate distance from sensitive areas

and sufficient depth, dispersion and/or die off of pollutants commensurate with the level of

treatment prior to discharge, to assure negligible environmental or health impact. Suitable

computer programs will be used to carry out the analysis to determine the location and the

basic.

design of the diffuser/ Intake structure. After the diffuser location is determined then the route

that the Marine intake outfall would follow will be established, the necessary internal diameter

to accommodate the flows anticipated throughout the useful life of the outfall will be

determined, and the method for protecting the outfall against the hydrodynamic forces of the

ocean would also be designed. The oceanographic information and data that is required to carry

this out includes following:

a) Topography, hydrography, and geomorphology of the sea bed which is used to determine the

route of the , Marine Intake Outfall

b) Wave and current data which are used to determine the method of physically stabilizing the

outfall.

c) Current data and salinity temperature profiles of the water column. This is used to

Determine the location and design of the diffuser, the static hydraulic head, and to the

Physical stability of the Marine Intake outfall.

5. SUBMARINE ROUTE SURVEY

Preliminary route survey of the Pipeline route will be conducted by using a DGPS System. By

establishing two control points on shore, it is possible to use triangulation to the buoys to record

the route with sufficient accuracy. The Marine Intake Outfall on-shore distance between the

triangulation points would not be less than

1/4 of the length of the Marine Intake Outfall.

Submarine route location survey will also be conducted by divers to locate problem areas such

as reefs, environmentally sensitive areas, large rocks, cliffs, drop-offs, high points, areas used for

ship anchorage, weak or unstable soils, and areas subject to erosion or deposition etc.

6. MARINE INVESTIGATIONS

Having established tentative Diffuser location and Pipeline route, fallowing activities may be

conducted.

a) Sonar determined bathymetry with horizontal control linked to a global positioning

System. Both the horizontal and vertical precision would be within one meter.

b) Side-scan sonar imaging to determine the geomorphology of the seabed.

c) Sea Currents.

c) Visual imaging of the possible Marine intake & outfall routes by use of video.

While carrying out activities related to Marine Survey fallowing precautions shall be taken

Safety

The generally hazardous nature of working at sea makes it imperative to have in place an

adequate safety program that will ensure the safe return of all personnel at the end of each

working day. Topics that should be addressed in any safety program include (but are not limited

to): Periodic first aid/CPR training,

Hazardous materials training,

The physical condition of the crew/field members and adequate training in the safe operation of

equipment used in the field to complete the survey.

Navigation

Accurate location of sites is important for any survey. In order to effectively meet this objective,

navigational equipment that will be aboard monitoring vessels is a Global Positioning System

(GPS) and a Fathometer. The GPS instrument would be capable of displaying Differential GPS

(DGPS) positions.

Throughout a survey work, the Team Leader will navigate to sites using a set of Nominal station

coordinates. The coordinates of each station location must be based on a determined Datum and

will be expressed in degrees, minutes,

and thousandths of a minute. Fathometer readings would be recorded in meters and

Direction (e.g. course and heading) would be reported as degrees from magnetic North. An

accurate log of general activities and specific site data sheets will be maintained.

Vessel and Site Data

A specific set of Vessel and site data will be recorded .

Following data would be recorded for each activity.

1) Date

2) Vessel

3) Crew

4) Check box indicating that the GPS system is functioning properly

Following standard data will be recorded

1) Date

2) Station coordinates of the actual work location

3) Time

4) Depth for each sampling position

5) Weather observations; sky, wind speed, and wind direction

6) Sea conditions; swell height, period and direction

7) Tide height, and time of low and high tides bracketing the sampling event.

8) Comments section

Additional specific types of data also will be recorded depending on the type of sampling being

conducted.

For water quality sampling these data might include:

1) Instrument identification if more than one CTD is used for sampling.

2) Specific depth information if any water samples are collected during a cast

For benthic sampling, additional data categories will include:

1) Time at which a replicate was sampled

2) Depth of sediment in grab

3) Sediment descriptions; to include color and type of sediment

4) Replicate identification; whether a sample was collected for community or

Chemical analysis

5) Checkboxes for each chemical constituents sampled

Hydrographic Survey shall be conductedtocollect information regarding Marine conditions. The

Proposed location of diffuser intake structure along with alignment of Pipeline shall be marked

with the help of DGPS and the Depth of the water column shall be measured by Echo Sounder.

Area covered under this Survey will be 1 Km. On either side of the Proposed location of the

Diffuser intake structure and 1 Km. Out towards sea. Equipment required for Survey shall be

mounted on a Survey Boat. Brief description of the system is as fallows.

BATHYMETRY AND

MICROTOPOGRRAHY.

In NMEA-0183 format for navigation

with high degree of accuracy. The

positioning data received will have

high reliability and integrity. The

system will be calibrated at a known

location within the survey area.

Navigation & Data Logging

HydroProis a world's leading

software solution provider for

navigation, hydrographic survey, data

acquisition and processing needs.

This will be interfaced to all the data

acquisition systems on board and the

data logged will be processed by

using Hydro Process data processing

software.

Vertical Control

Observed tides close to the survey area will be used for converting raw water depths to chart

datum.

Echo sounder

ODOM DF3200 MKII Dual frequency or equivalent Echo sounder, integrated with a DGPS

positioning system will be used during the entire survey to record geographically referenced

bathymetric data for measuring water depths. Sea

swell will be eliminated by SETEX MRU 5 motion sensor (heave compensator). Digitized data

will be confirmed by the inspection of analogue records.

Depth contours (Sea Bottom Topography) over the same area shall be studied by using Side Scan

Sonar as fallows.

Side Scan Sonar

EG & G 272TD dual channel `towfish' and an EG & G 260 recorder (or equivalent) will be

provided to investigate the sea floor for morphology and other features. The survey lines will be

run with a range setting of 50 meters either side at a scanning frequency of 100 KHz along the

survey lines. The tow system will be operated following recommended manufacturers

procedures. The tow fish will be towed astern of the survey vessel at a depth providing optimum

seabed return. Layback and cable-out will be logged from each survey line..

TIDES, CURRENTS AND CIRCULATION

Anderra(or equivalent) Current meters shall be used for measuring currents at various locations

and tide poles measurements shall be undertaken to measure the tides. Float drogues shall be

released and monitors to study the circulation patterns.

Processing of Data

The survey data logged in Hydro Profile format will be processed in Hydro Process software and

finally presented in drawing form using AutoCAD Rel.14 for windows.

WATER-COLUMN PROFILING

Purpose

Water-column profiles will be collected at sampling sites to characterize depth related gradients

in temperature, salinity, hydrogen ion content (pH), transmissivity, Dissolved oxygen (DO), and

chlorophyll fluorescence. For example, water-column

Profiles can describe whether stratification (layering) is present and, if so, the depth of the

thermoclineor pycnocline. Variation in these parameters at the same depth among Stations may

indicate anthropogenic or natural perturbations of the environment: low Salinity values at some

stations may indicate the presence of an effluent plume whereas high pH and dissolved oxygen,

and low transmissivitymay indicate a phytoplankton bloom.

Equipment

A conductivity-temperature-depth profiler (CTD) with an expanded compliment of Sensors will

be used to provide a continuous water-column profile of the attributes

Described above.

Pre Survey Equipment Checkout

A pre-survey equipment checkout will be conducted before calibrating the sensors and

Also within 24 hrs prior to starting the work. The inspection will include following:

1) Visually inspect the CTD for any obvious defects.

2) Check all metal components for corrosion and clean or replace as necessary.

3) Inspect and clean all of the sub sea connections with contact cleaner as

Necessary.

4) Lubricate newly cleaned connectors with silicone grease and ensure they are Securely

reconnected.

5) Check all cables for nicks, cuts, abrasions, or other signs of physical damage.

6) Test the CTD to see if connections and software work properly.

7) Clean or replace all accessory tubing as necessary.

8) Check the battery status for all units using RAM data storage.

CTD Pre-Survey Calibration and Equipment Checkout

Pre-survey Calibration

Equipment checkout and calibration will be carried out as per the specific recommendations of

manufacturers. General procedure is given below; however it is subject to change at the time of

actual work.

Hydrogen Ion Content (pH)

The pH sensor is calibrated by employing commercially available buffer solutions as Standards.

When sampling in the ocean it is best to bracket the

pH range by using the Three buffers, pH 7, 8, and 9. It is important that the buffer is thermally

Equilibrated with the water bath; this is best accomplished by keeping the CTD in the Water

bath and by using a holding bracket for the buffer container. Depending on the CTD model, the

appropriate readings for each of the three buffers (e.g. water

Temperature, pH, and voltage output) should be recorded on the calibration log. The pH probe

should be adjusted according to the manufacturer‟s specifications using this Information.

Agreement between the measured sensor output and the known buffer values should be within

+/-0.1 pH units. If this range is exceeded, the buffer readings should be used to calculate the

values necessary to properly adjust the pH sensor. When the calibration has been successfully

completed, the pH electrode should be stored in a KCL-saturated, pH 4 buffer solutions.

Dissolved Oxygen (DO) Ensure that the pump being used to supply water to the sensor during

the calibration is operating correctly and that it flows within the factory specifications. Compare

the sensor-measured DO values with the saturation values taken from the most recent edition of

Standard Methods; it should match to within 0.1 ml/L (0.143 mg/L). Sensor performance should

be Information. Agreement between the measured sensor output and the known buffer values

should be within +/-0.1 pH units. If this range is exceeded, the buffer readings should be used to

calculate the values necessary to properly adjust the pH sensor. When the calibration has been

successfully completed, the pH electrode should be stored in a KCL-saturated, pH 4 buffer

solutions.

Dissolved Oxygen (DO) Ensure that the pump being used to supply water to the sensor during

the calibration is operating correctly and that it flows within the factory specifications. Compare

the sensor-measured DO values with the saturation values taken from the most recent edition of

Standard Methods; it should match to within 0.1 ml/L (0.143 mg/L). Sensor performance should

be monitored over time and it must either be repaired or replaced if the results do not meet the

manufacturer‟s minimum specifications. TransmissometerThe transmissometershould be

calibrated prior to each sampling survey according to the manufacturer‟s recommended

procedures. FluorometerThis calibration is performed using a 50 μg/L solution of

Coproporphyrinas a substitute for chlorophyll (a) and distilled water for a blank. Pressure The

pressure sensor should be checked before each sampling survey. Again, follow the factory

recommended adjustment procedures. The pressure reading in air at sea level should be a

negative number between 0.00 and -0.60 decibars(db). If the correct pressure cannot be

displayed by adjusting the offset, the manufacturer should service the sensor as soon as possible.

CTD Deployment

The objective of water-column profiling is to collect data for every meter of depth while

Lowering the CTD. Ideally a scan-rate of eight scans per second or greater may be used. The

absolute minimum scan-rate is two scans per second and should be reserved for use in small

bodies of water, where deploying smaller units is more practical. In larger bodies of water,

where larger units are easier to deploy, it is strongly recommended that the scan-rate be eight

scans per second. Some manufacturers‟ software allow the descent rate to be monitored

digitally when the CTD is deployed using a real-time means of data collection by displaying and

viewing lowering rate variable. Descent rates should always be greater than the upward

acceleration of the instrument caused by the swell to minimize shed wake spiking of the data.

Onboard water bath will be used for the CTD to prevent excessive heating of the sensors while

traveling between stations. Rinse the lenses of the transmissometerwith deionizedwater to

remove any crystallized salt prior to each cast.

Before beginning a cast where dissolved oxygen is being measured, the sensor will be brought to

thermal equilibration with the ambient sea-water by soaking the CTD for a minimum of three

minutes at the first station of the day and for 90 seconds at every station thereafter. Surface

equilibration time is performed for two reasons; DO sensor re-polarization and thermal

equilibration. Additionally, air bubbles may become trapped in the CTD‟s tubing that can

adversely affect the performance of the DO sensor unless they are removed. The air bubbles can

be purged from the tubing simply by lowering the unit five meters below the surface for a short

time, then raising it back to the surface so that the top of the CTD is just below the surface prior

to starting the cast. The recommended optimal descent rate while lowering the CTD is 1 m/s.

BENTHIC SAMPLING

Purpose

The purpose of benthic sampling is to obtain at each site one or more samples of the

Seafloor sediment. The Sediment samples are used to describe the biological physical and

chemical Characteristics of the site. This information is particularly useful in characterizing the

Extent and impact of The discharge from an outfall relative to the prevailing natural conditions.

Equipment A 0.1 m2 modified Van Veengrab will be used to collect sediment samples for

physical, chemical, and infaunalanalysis. The grab may be galvanized, stainless steel, or Teflon-

coated. All surfaces of the grab must be clean and free of rust. Either single or tandem-rigged Van

Veengrabs may be used. Tandem-rigged Van Veengrabs are two grabs mounted on a shared

hinge pin.

Grab Sampling Procedures

Prior to deployment, the grab will be cocked and then the safety key will be put in place. The

grab is next hoisted over the side; the safety key is removed and then lowered at a rate of

approximately 2 m/sec until it is about 5 m above the bottom. From this point, it is lowered at 1

m/sec to minimize the effects of bow wave disturbance. After bottom contact has been made

(indicated by slack in the hydro wire), the tension on the wire is slowly increased which causes

the lever arms to close the grab. The grab is then brought back to the surface and retrieved back

on deck as quickly and as safely as possible to avoid any “washing” at the surface caused by the

boat rolling in the sea. Once the grab is back onboard, the top doors are opened so that the

sample can be inspected.

Criteria for Acceptable Grab Samples Before the grab can be processed, the acceptability of the

sample must be determined.

This determination is based upon sample condition and depth of penetration. Sample

condition is judged using criteria for surface disturbance, leakage, canting, and washing. An

acceptable sample condition is characterized by an even surface, with minimal surface

disturbance, and little or no leakage of the overlying water. Heavily canted samples are

unacceptable. A sample with a large amount of humping along the midline of the grab, an

indication the sample was “washed” during retrieval, is also Unacceptable. While some humping

might be evident in samples taken from firmer substrates, this is primarily due to the closing

action of the grab and is not evidence of nunacceptable washing.

If the sample condition is deemed acceptable, the overlying water is drained into an Underlying

container by slightly opening the jaws of the grab. This water must be Retained for later

screening with the sediments (see Sample Processing below). Extra Caution should be taken to

drain the overlying water from the grabs for chemistry and Toxicity samples so as to avoid

disturbance and loss of the surface sediments. The next step in processing the grab is measuring

the depth of penetration. For infaunalsamples, sediment penetration depth must be at least 5

cm; however, penetration depths of at least 7-10 cm should be obtainable in silt (fine sand to

clay). Inserting a plastic ruler vertically along the grab midline and measuring the depth of the

sediment to the nearest 0.5 cm determines the depth of penetration.

Sediment Description

Sediment characteristics will be described following the measurement of penetration depth. The

general sediment type will be characterized (e.g., clay, silt, sand, gravel, or any combination of

these) and if the sample contains large quantities of shell hash, this should also be noted on the

data sheet. The presence of petroleum tar should be recorded, as well as any obvious odors such

as sulfides (the odor of H2S or rotten eggs), oil (the odor of petroleum tar), or humicsmells (a

musty, organic odor). Sediments will usually have no particular odor. General sediment color

(e.g., black, green, brown, red, yellow) will also be recorded .

Sample Processing

Benthic InfaunalSamples

After the sample description has been completed, the sediment sample intended for

Infaunalanalysis is washed completely from the sampler, saving sediment, overlying

Seawater, and wash water for subsequent screening. All raw wash waters used on the

Sample are to be filtered in some fashion to preclude the accidental introduction of

Surface-water organisms. Two methods that may be used are an in-line filter in the boat's

seawater pumping system, or the fitting of all wash hoses with fan nozzles having small

apertures (<0.5 mm diameter).

A sediment-washing table is recommended for benthic sample processing. The table

Provides a flat, smooth surface over which to spread and wash the sample. This provides a

means of gently breaking up the sediment before it runs off the end of the table into the screen

box. The screen box must be equipped with a stainless steel mesh with 1.0-mm openings. Wire

diameter should be similar to that found in the Standard 1.00 mm Sieve . The surface area of

screen should be adequate to easily accept the sample without build up. Water pressure should

be controlled while washing the sample to avoid damaging the organisms. Minimize direct

application of water from the hose to the material and organisms collecting on the screen.

Once the sample has been washed through the screen, the material (debris, coarse Sediment, and

organisms) retained on the screen should be transferred to a sample Container. The sample

container should be labeled with an external, water resistant Adhesive label naming the station,

depth, date, replicate and "split number" (i.e. 1 of 2, 2 of 2, etc.), if applicable. This label should

be waterproof and marked using a pencil or indelible ink.

The sample container will have an adequate watertight closure and be sufficiently large to

accommodate the sample material, relaxant and fixative. If necessary, a sample may be split

between two or more containers, however, each container must have the appropriate labels

(described above) with the corresponding split number clearly marked. Splitting samples should

be avoided if possible. Splitting samples is usually unnecessary if the field crews have a broad

range of sample container sizes available.

The material retained on the screen should be gently removed in order to avoid damaging the

organisms. The sample container should be filled to approximately 40% (no more than 50%) of

capacity with screened material. After the sample material has been transferred to the container,

the screen should be closely examined for any remaining organisms caught in the mesh. Those

organisms should be removed with forceps and added to the sample container. The screen box

should be thoroughly washed and the mesh scrubbed with a stiff brush before the next sample is

screened.

It is recommended that all infaunalsamples be treated with a relaxant solution for

Approximately 30 minutes prior to fixation. Either an Epsom salts (MgSO4) solution or a

propylene phenoxytolsolution may be used for this purpose. The relaxant solution may be used

as the diluentwater for the fixative, or may be decanted after exposure and replaced with diluted

fixative.

If the relaxant is used as diluentwater, fill the sample container to 80% of its volume,

Close the container and invert it several times to distribute the solution. Leave the sample in the

relaxant for 30 minutes. After 30 minutes top off the container with enough sodium borate

buffered formalin to achieve a 10% formalin solution. Close the container once again and invert

it several times to assure mixing. Store the sample for return to the laboratory.

If the relaxant solution is not used as the diluentwater, the relaxant must be removed

From the sample container and replaced with 10% formalin. After the 30-minute

Treatment, decant the relaxant from the sample through a screen with a mesh size of less than

1.0 mm. Make sure that all of the material and animals have been removed from the screen and

placed in the sample container. Fill the sample container with a 10% solution of sodium borate

buffered formalin rather than with undiluted formalin. Close the container, invert it several

times to assure mixing and then store it for return to the laboratory.

Relaxant and fixative stock solutions are as follows:

1) Epsom salts relaxant solution: 1.5 kg Epsom salts (MgSO4· 7H2O)

per 20 L of freshwater.

2) Propylene phenoxytolsolution: 30 ml propylene phenoxytolto 20 L

of seawater.

3) Buffered formalin solution: 50 g sodium borate (NA2B4O7) per

liter of formalin.

4) Buffered 10% formalin solution: 1 part buffered formalin solution to 9

parts fresh or salt water.

Sediment grain-size and chemistry (e.g., TOC, trace metals, trace organics) samples will be

collected from the top 2 cm by randomly subsamplingundisturbed surface material with a

stainless steel, Teflon-coated, or plastic scoop. A metallic scoop should be replaced if any signs of

rust are visible. Sediment in contact with, or within 1 cm of the metal sides of the grab should be

avoided to reduce the chance of sample contamination (e.g. metals, organics, etc.). Care should

be taken not to touch any surfaces of the grab Sampler with the scoop. At a minimum, the scoop

will be thoroughly rinsed to remove any traces of sediment form the previous station then

stored to avoid being contaminated between stations. Chemistry samples should always be

placed in precleanedcontainers. Sediment grain size and some sediment chemistry (e.g., TOC and

trace metals) samples can be collected in glass or plastic containers, but trace organics samples

should always be made of glass. Sediment chemistry sample containers should have Teflon-lined

lids, although this is not a requirement for sediment grain-size samples. An air space should be

left at the top of each sample.

Quality Assurance

The quality of benthic sediment samples is dependent on following the field procedures

1) Prior to each deployment the interior of the grab must be thoroughly washed

With seawater to remove any sediment from the previous sample.

2) Once the grab is returned to the surface, it should be recovered as quickly as Safe handling

permits as a means of avoiding sample washing as the boat rolls in the sea.

3) The grab sample should be visually inspected to ensure the overall condition is Acceptable

and it should be measured to guarantee the minimum depth of Penetration.

4) Gentle water pressure should be employed when washing and screening the

Infaunalsamples to avoid damaging any of the organisms.

5) The screen must be thoroughly washed and scrubbed between samples.

6) A relaxant is recommended for use on all infaunalsamples to minimize Fragmentation of the

organisms during fixation.

7) The infaunalsample container should be filled no more than 40% full of Screening material.

After adding relaxant and fixative solutions, the container needs to be inverted several times to

assure a thorough mixing and exposure to Relaxant and fixative.

8) Timers should be used to ensure that fixation of the samples takes place 30

Minutes after being exposed to the relaxant solution A distinctive sticker may be Affixed to the

lid of the sample container to visually distinguish between the Samples being treated with

relaxant and those having been fixed.

9) Extra care should be taken when draining the overlying water from grabs

Intended for chemistry samples. This minimizes disturbance and loss of surficialSediments. Use

of a tygontubing siphon is highly recommended.

10) Field personnel must be thoroughly trained to recognize and avoid potential Sources of

contamination of chemistry samples (e.g., engine exhaust, winch wires, Deck surfaces, ice used

for cooling).

11) Grabs for sediment chemistry samples must be of similar sediment type and Have similar

penetration as the grab used for the infaunalsample. This is to ensure an adequate volume of

surface sediments for subsampling, and that the chemistry Samples come from sediments of

similar character as the infaunalsample. Tandem-rigged Van Veengrabs can facilitate this by

simultaneously collecting sediment samples from the same site for chemistry and benthic

analyses.

12) Sample devices that come in direct contact with the chemistry sample

sediment should be made of non-contaminating materials (e.g. plastic, glass, high

quality stainless steel, and/or Teflon) and should be thoroughly cleaned between

Sampling stations.

13) Chemistry sample containers must be of the recommended type of material

and must be carefully precleaned.

14) Sample holding conditions and holding times specified for chemistry samples

Must be followed explicitly.

SOIL INVESTIGATION

Soil Investigation will be carried out at the Proposed location of Diffuser and along the proposed

Pipeline route by drilling Boreholes. Location of the Boreholes will be decided in consultation

with Design Engineers. It is assumed at this stage that on Marine side 5 bore holes will be drilled.

Depth of the Boreholes considered is 20M.s

Wherever required by the Seabed conditions Rotary Drilling Method along with Mud Circulation

technique will be used in order to ensure borehole stability in unconsolidated soils.

Equipment to be used for this purpose will be Hydraulic Voldrill90 mounted on a Spud Barge.

Procedure to be fallowed will be in accordance with B.S. 5930-1999.The InsituTests and visual

analysis made during Site Investigation will be augmented by a series of Laboratory Tests. Tests

on Soil samples will be carried out in accordance with B.S.-1377(1990) “Methods of Test for Soil

for Civil engineering Purposes.” Test to be carried out will be as fallows.

1) Grain Size Analysis (BS 1377:1990: Part2)

2) Chemical Analysis (BS 1377:1990: Part3)

3) Natural Moisture Content Test. (BS 1377:1990: Part2)

4) AtterbergLimit Determinations (BS 1377:1990: Part2)

5) Bulk Density Test. (BS 1377:1990: Part2)

6) Organic Matter Content (BS 1377:1990: Part3)

7) Compaction Test. (BS 1377:1990: Part4)

8) Specific Gravity Test. (BS 1377:1990: Part2)

9) California Bearing Ratio Test (ASTM D1883)

10) Unconfined Compression Test (ASTM D 2938)

Based on the Observations and all the results obtained from insituTest and Laboratory Tests

Final Report shall be submitted. This Report will be used to derive recommendations on

Designing suitable Anchor foundations for the Diffuser and Pipeline.

DISPERSION MODEL

Dispersion Model test to show the practical suitability of the Sea Outfall and size the diffusers

required at the end of the in co-Marine Intake & Outfall ordination with MRMEWR. Services of a

well-experienced, very well known and well-equipped Organization in the field of marine

modeling will be utilized for undertaking this work. National Environmental Engineering

Research Institute (NEERI) will be associated with us for dispersion Model studies and EIA.

Their profile and facilities are attached as Annexure.

Hydrodynamics of an effluent continuously discharging in to a receiving body can be

conceptualized as a mixing process occurring in two separate regions. In the first region the

momentum flux, buoyancy flux and outfall geometry influence the jet trajectory and mixing. This

region is called as near field. At the end of the initial mixing region the waste field is established.

Conditions prevailing in the ambient environment will control trajectory and dilution of the

turbulent plume through buoyant spreading motion. This

region is referred to as far field or dispersion zone.

The Cornell Mixing Zone Expert Marine Intake & Outfall System (CORMIX) is a series of software

elements for analysis and design of submerged buoyant or non-buoyant discharge containing

conventional or toxic pollutants in to stratified waters with emphasis on the geometry and

dilution characteristics of the initial mixing zone. CORMIX2 addresses multyportDiffusers

/intake structure. This expert system developed by EPA of USA IS ACCEPTED internationally as

an excellent tool to provide information in initial Dilution.CORMIXsoftware is proposed to be

used to predict initial dilution under various tidal conditions. The inputs required for predicting

initial Dilutions in the pre design stage will be obtained from the Marine Surveys and

Investigations.

There are several mathematical models used for hydraulic studies for dispersion patterns at far

field of the. MIKE21 software developed by DHL Denmark can model wave transformation,

Currents due to waves and tides, advection and dispersion, water quality, mud and sand

transport etc. This software will be used to carry out the Dispersion Model of the far field.

MIKE21 is a well-proven professional engineering and extensively used software package for

simulation of flows, waves, sediments and ecology. T he two dimensional modeling system is

designed in an integrated modular framework with a variety of add on modules. It is possible to

match and study almost any real world free surface water phenomena using this software.

Further more these simulations tools facilitate easy application at all project stages. This

Software will be used at all the stages of the Project from feasibility through design, Construction

to Operation and Maintenance.

MIKE21 Provides

• A complete and effective design environment with flexible and easy water quality modeling.

• Advanced Graphical user interphasecombined with a series of efficient computational engines.

• GIS Integration

• Free tools e.g. for processing of model data in MATLAB.

• Modules for virtually any kind of 2D water modeling.

• Sophisticated tools for data handling, analysis and visualization.

• Multiple Computational grid option ensuring optimal model application.

The seawater quality and coral population, if any will be Periodically monitored, to assess any

change/impact due to discharge of wastewater.

DESIGN & ENGINEERING

After receiving the necessary approvals to the survey and modeling works, a Design Philosophy

Report for the Marine Intake & Outfall shall be prepared, that presents a conforming Outfall

option using the materials, pipe sizes, diffuser dimensions, burial, cover, rock fill and all other

arrangements for the Outfall, together with construction methods to install, secure, verify and

commission the Outfall.

Preliminary data based on Design at the Proposal stage is as fallows.

Intake Pipeline

• Pipeline material-OD 1600 HDPE pipe -1042m,2NosOD 90 HDPE pipe -1042m.

• Pipeline diameter -OD 1200 HDPE pipe 620m

• Diffuser diameter 1200mm, Tapered, length 50m

• Trench excavation depth to provide 1.5 mtrson top of the pipes.

• Depth of cover for offshore pipeline------------------------(will be installed by float and

( sink Method.

• Backfill and rock protection --------------------------------Only wherever required.

• Arrangement of diffuser ports -------------------------------Inclined at 45 degrees to the

axis Of Pipeline alternatively in Opposite direction.

Information stated above is subject to change at final Design stage.

The Design Philosophy Report shall contain a thorough design analysis and report

And the analysis will include following aspects

• Foundation conditions and settlement

• Marine Intake & Outfall hydraulics and air removal

• Loads on pipeline, including buoyancy

• Pipeline materials, including corrosion protection and service life

• Transition between different seabed materials and sediments.

• Concrete weights, tie-downs or anchors

• Protection of pipeline and diffuser risers and ports from Damage

Fallowing aspects will be taken in to account in designing.

• Materials selected for the pipeline and diffusers, and joints should prevent ingress of seawater

and sediment, and preclude corrosion as far as practicable

• The ports shall be designed (and opened over time) to prevent seawater intrusion into the

conduit. The FoudeNumber at every port shall exceed 2.0 at the minimum flow (but not when

the flow to the Marine Intake & Outfall is shut off)

• The diffuser ports should be designed to facilitate replacement in case of damage by a dragged

anchor, net or any other reason by providing a coupling or flange connection

in the riser above the sea floor and a designed weak point at the coupling or flange

• Diffusers and/or rock armourshall be designed to facilitate shedding of dragged nets and

trawls

• All portions of the Marine Intake & Outfall in navigable waters shall be sufficiently

protected by either depth of cover and/or armouringto survive anchors dragging across the

pipeline

• The ports shall be designed to facilitate entry by remotely operated inspection devices such as

TV cameras

• The pipe radius shall not exceed 20 % of the pipes critical radius of curvature during all pipe

handling operations, installation and service

• The minimum design pressure rating shall achieve a minimum factor of safety of 1.5 for the

maximum operating internal pressure

• Pigging of outlet to diffuser, prior to diffuser installation

• Pressure testing of Marine Intake & Outfall sections and entire Marine Intake & Outfall with

Diffuser / intake structure

• Post construction survey

• Head loss flow once flow is initiated

7. SUPPLY AND INSTALLATION

DIFFUSER / Intake Structure.

Design of the Diffuser envisaged in this Proposal will be with objective to achieve balanced flow

distribution under most of the operational conditions with minimized energy loss. The

hydraulics occurring both outside and inside of diffuser/ intake structure will be carefully

considered. Final design will be based on the external environmental hydraulics, which deals

with effluent mixing with the ambient fluid downstream of the ports and Internal hydraulics

including flow partitioning and related pressure losses along the manifold, which will result in

discharge profile along the diffuser.

.

Based on the data made available at this stage, the Diffuser / intake structure intake structure

shall be made out of a Pipe of 1.2 m. internal Diameter and 50 m. long, which disposes 5,796 Cu.

M. per hour under 10 water column head by gravity discharge. It may be tapered towards

upstream for increasing the diffuser / velocities for scouring purpose, and fitted with number of

risers at an angle of 45 degrees to the axis of the pipeline and alternately in opposite direction

(One to the right side and other to the left side of the Axis of Pipeline.)

DREDGING & TRENCHING

The work relating to dredging a trench for laying . Pipeline material-OD 1600 HDPE pipe -

1042m,2NosOD 90 HDPE pipe -1042m. Pipeline diameter -OD 1200 HDPE pipe 620m.

2. SCOPE OF WORK

2 2.1 SCOPE OF WORK

Excavation of trench upto35m water depth for laying 30inch submarine pipelines and back

filling with local material & engineered material as required

2.1.1 Excavation trench from LFP to KP , inter tidal zone KP 0. to KP and shallow water from KP

to KP along with pipe line route which is being laid for M/s PETROIRAN OFFSHORE FACILITIES

as per requirement and specifications of the client

2.1.2 Once the pipe is laid in the pipe line trench in the dredged channel, work involves back

filling the trench with local material earlier dredged or new material dredged from nearby or

transported from ashore & graded stones and an armourlayer of rocks ..

2.1.3 The trench to be excavated will have width of 2 Mt. At bottom and depth of 3 Mt

2.1.4 Provision of Survey equipment and personnel to carry out the survey of the trench for

correct dimensions.

The dredged material shall be disposed of at approved dumping ground about 1000 Mts. away

from the pipe line route as approved by the port authorities.

The side slopes shall be such that the trench shall be stable under the site conditions that prevail

at the site for the time required.

3

4 2.2 SEQUENCE OF ACTIVITIES

-Mobilisationof marine spread, vessels, crafts for dredging and trenching.

-Provide manpower for the dredging and trenching works.

-Project Management for dredging and trenching works.

-Planning, organisingand progress monitoring.

-Provide positioning services.

-Pre-dredging survey

-Intermediate dredging surveys

-Post dredging surveys

-Dredging and trenching by dipper Dredger and Cutter dredger

-Dumping of dredged material at designated dumping location.

-Conduct/Perform maintenance dredging until pipeline laying.

-Measure progress of dredging and trenching works

-Clear site of all debris and construction equipment

-Demobilisationof marine spread, vessels and crafts, personnel, site office etc.

5 2.3 TRENCH DIMENSIONS

The trench dimensions etc. envisaged in the tender are proposed to be modified partially as

under, after detailed study of site conditions etc and all relevant drawings including trench

profiles, alignment and cross sections etc.

Note: Side slopes shall be 1 : 3

3.0 PROCEDURE FOR PRE-TRENCHING BY DREDGING

6 3.1 INTRODUCTION

Work involves Pre-trenching by dredging from ChainageKP to ChainageKP dredging of coral

rufsoil like corals, sand stone / clay and other materials not exceeding compressive strength of

3.2 .

7 3.2 TRENCHING IN SOFT SOIL

MARINE SPREAD

The following Marine Spread for dredging and disposal of soft soil and clay will be utilized

-Shallow portion with Excavators -Shallow zone upto5 mtrsdepth with cutter section dredgers

-Up to ---mtrswater depth with Dipper Dredger in combination with hopper barges and tugs

The dipper Dredger (1 No.) and Cutter section Dredger (2 No.) and Excavator ( 1 No. ) will be

utilized for excavation of the trench by dredging. Hopper barges and tugs shall be used for

transportation of the dredged material from the dredging area to the designated dumping

grounds and disposal.

Dipper dredger –working method

Non propelled dipper dredger will be towed to dredging place and positioned with the help

DGPS system using navigation software. Necessary data will be fed into the onboard computer to

maintain trench section profile and depth. Dredging operation involves lowering of the

excavator‟s bucket to the sea bed level, excavation of the material and discharging dredged

material in the along side placed hopper barge. The barge is utilized for transportation and

disposal of the dredged material at designated dumping with the help of a towing tug.

CUTTER SECTION DREDGER

Cutter section dredger will be positioned on pipe line route with the help of DGPS system. The

dredged material will be discharged about 500 Mts. away with help of pipes. .

8 3.3 PRE-TRENCHING –SEQUENCING IN SECTIONS

Land portion trenching will be done with help of excavators.

Shallow water upto5 mtrsdepth -Will be carried out with the help of Cutter section dredgers.

Shallow water /deep water dredging we propose to mobilisea Dipper dredger “Obscured By

Clouds”. The dredger is fitted with 16 Mts. boom, 9.5 Mts. stick suitable 4.5 M3bucket.

The Boom and stic6s can be changed for required depths.

The Dipper dredger will be supported by two number of hopper barges of approx. 450 M3 and

towing Tugs to collect the excavated material and for dumping.

The excavated material shall be disposed off at a distance of approx. 1000 Mtrsaway, along the

pipe line route near the beach for reusing the same material for backfill. Floating buoy will be

placed to mark the position.

Survey Boat duly fitted with echo sounder will keep on checking the trench till the pipe lay barge

is mobilized and pipe is pulled in the trench.

We expect considering the soil a trench with 4 Mtrsat the bottom and 1:3 slope should stabilize

and trench should stay till pipe pull is completed.

9 3.5 DUMPING GROUND

The dredged material is transported through hopper barges and dumped at dumping ground or

1000 m away from the pipe line route as explained above.

10 3.6 DREDGING -CONTINGENCY PLAN

UNEVEN BED LEVELS / OVER DREDGING

The dredger “Obscured By Clouds” is fitted with Seatecon board, every bucket operation is

monitored and there is very little scope of over dredging. However, over dredging, if any, over

the permitted tolerances will be known immediately upon survey of that area and excavation

will continue at this level to bring the trench bottom close to natural flexibility tolerance.

UNDER DREDGING

After completion of dredging, post-dredging survey shall be conducted. In case, the designed

depths have not been achieved, the area shall be re-dredged to attain the designed level.

TOLERANCES

Vertical –0 to + 30 cm and horizontal –Nil tolerance as required shall be maintained. There is no

tolerance above the bed level or within the minimum trench width stipulated in the contract.

SIDE SLOPES

Dredging plan shall take care of 1:3 side slopes as required in designed width of the trench

before the pipeline is laid

MAINTENANCE DREDGING

Before the pipeline is laid, the area shall be surveyed to see whether profile of the trench is

maintained or not. If the profile is not maintained, the area shall be re-dredged and the trench

profile is obtained as per the design.

BACK FILLING -The excavated material dumped near the beach, KP and KP will be loaded into

the split hopper barges with help of Excavator/dredger and transported to the pipe line. With

the help of survey boat, split hopper barges will be guided across the trench , to discharge, in

order to lock the pipe in the trench at every 50 ML. After locking the pipe in the trench, hopper

barge will discharge the material over the pipe line route travelling over the trench and

discharge, still with help of survey boat, second hopper barge material overlapping the discharge

from the previous hopper barge and so on to complete the back filling operation alternatively.---

---------------

Cutter section shall be placed about 100 Mts. away parallel to the pipe line route and discharge

shall be guided in to the trench

REPORTING

Daily Progress Report indicating the KP chainagevalues, environmental parameters, survey

analysis of trench profiles, quantity dredged, number of loads shall be furnished. Individual daily

progress reports for each hopper barge will be prepared and enclosed with the main report.

4. SCHEDULE OF OPERATIONS

11 4.1 WORK SCHEDULE

The work schedule for execution of the work is furnished in Bar Chart attached

4.2 IHS surveys shall be conducted in following phases of work to determine trench

profiles:

1) Pre-dredging survey to ascertain the existing bed levels

2) Intermediate surveys as required to access the progress

3) Post-dredging survey to ensure that the levels after dredging complies with the specifications.

5. EXECUTION PLAN

One dipper dredger, one cutter section dredger and excavator 300 supported by hopper barges,

tugs and other supporting vessels shall be deployed for execution of the work

PIPELINE.

This Proposal is based on Pipe Diameter as 1600 HDPE –1042 MTRS 2 NosOD 90 HDPE pipe -

1042mtr –OD 1200 HDPE pipe –620m. mm and length of the pipeline

3 Km. The pipe material proposed to be used is HDPE Pipe, Manufactured by Amiantitof Oman or

equivalent.

Pipe of these materials have fallowing advantages:

a) It is light in weight and, thus, requires no specialized handling equipment.

b) An outfall pipeline can be quickly fabricated on shore by butt fusion.

c) Correctly butt fused joints are stronger than the pipe itself essentially precluding future leaks

at the joint due to settlement or movement.

d) HDPE pipe is sufficiently flexible for it to be installed on a tortuous route

e) The butt fusion method of joining is sufficiently rapid to enable the fabrication of long

Ocean Marine Intake & Outfall.

f) Polyethylene is essentially immune to the corrosive effects of seawater and attack by marine

organisms.

g) The HDPE pipe is light enough, yet strong enough to be pulled and floated into place using a

tugboat for towing and small boats for alignment of the outfall.

h) If necessary, the pipe can be re-floated by injectinof compressed air.

HDPE pipe is suitable for bottoms of sand, mud gravel and small rocks but requires external

weights (usually concrete) or mechanical anchors to hold it in place and prevent it from floating

of from moving due to hydrodynamic forces. It can also be placed on a seabed of rock as long as

the pipe itself is not resting on a point or sharp ridge.

PIPE DIAMETER SELECTION

Selection of pipe diameter for HDPE Marine Intake & Outfall is made through the same series of

determinations as for other pipe material. This is usually done through a balancing of friction

loss reduction against the flow velocities necessary to maintain sufficient scour to prevent

deposition of suspended solids, or grease build up on the pipe wall. New HDPE pipe has excellent

flow characteristics. Because of its exceptionally smooth its Hazen and Williams Formula

coefficient of C = 155 but for outfalls that have been in use the C is usually estimated to be 140

due to build up of grease on the pipe wall.

For sewage outfalls utilizing HDPE, the flow velocity ranges that have proven satisfactory

from both a friction and a cleansing standpoint usually fall within the ranges of 2 to 3 m/s. The

amount of and characteristics of the suspended solids and grease in the effluent influences the

necessary velocity for self-cleansing.

It is important that cleansing velocities be achieved at least one time every day for a sufficient

period of time to obtain complete flushing of the line. If this does not occur, depositions of solids

and bacterial growth on the walls will occur and it will be necessary to send a cleaning plug (a

pig) through the outfall at regular intervals to prevent pipe constriction or closure. When

designing an outfall for a 100-year projected flow it is important

check the velocities at the present maximum flows to see if sufficient scour velocities are

obtained during the first few years of operation. If not, then a maintenance schedule utilizing a

cleaning plug would have to be implemented until such time that flows reach a level to obtain

cleansing velocities. Facilities for the removal of grit and grease from the effluent prior to its

discharge into the outfall will help minimize problems due to deposition and is recommended.

This removal of grease along with floatable serves a second purpose of maintaining

Acceptable aesthetic conditions. Computer programs will be used to develop a head loss-

discharge curves for of Pipe to facilitate the selection of an optimal diameter. HDPE plastic pipe

is described by a specified exterior diameter and by a minimum wall thickness needed to obtain

the pressure rating of the pipe. it may well be assumed that the highest tide and peak sewage

flow can probably occur simultaneously. The submarine outfall and appurtenances such as flow

equalizers of pumps should be designed accordingly, so as to avoid undesirable surcharge of

gravity sewers that have service connections. The fact that seawater has a density that is

approximately 2.5 percent greater that the density of sewage also to be taken into account. This

static head must be overcome by the gravity head available.

In the ocean normalytidally driven strong currents occur twice a day. Tidally generated

movement of water can also reach high velocities on a daily basis. Frequently such areas have

geomorphologicallysheltered from the open ocean and are thereby protected from large waves.

In such cases the currents are the critical factor in determining the method of stabilizing the

outfall. An equation that can be used to evaluate the necessary ballast weight necessary to

stabilize a HDPE Pipeline against a current perpendicular to the centerline of the outfall is…

WB= the buoyant weight (submerged weight of the Marine Intake & Outfall) of length L

CD = the drag coefficient

CL = the lift coefficient

r = the mass density of seawater (the unit weight of seawater divide by acceleration of gravity)

ms = the static friction coefficient between the ballast anchor (or pipe wall) and the seabed

D = pipe diameter

L = length of pipe section considered (usually a length of 1 meter)

V = the velocity of the current moving perpendicular to the pipe

It is important to note that WB is the submerged weight of the outfall not the weight in air. This

can be calculated by multiplying the weight in air by (the sink factor –1). The sink factor is

explained in the following sections. The friction factor ms varies between about 0.6 and 1.4 for

sand and between 0.2 and 0.7 for silt and clay.

It is critically important to take into consideration the forces that are exerted by ocean waves on

a submarine Marine Intake & Outfall Pipeline particularly where the outfalls extend from a

coastline facing the open ocean especially in regions that are frequented by hurricanes or other

violent storms. The first step is to decide on a recurrence interval of a rare but possible deep-

water wave that would travel to the Marine Intake & Outfall site during the useful life of the

submarine outfall being planned. For ocean outfalls a common

Recurrence interval (return period) is 50 years and sometimes a rather conservative interval of

100 years is used.

Historical database of storms and hurricanes that pass within a selected radial distance of the

outfall site will be analysed. A distance of 300 nautical miles is a common figure used for this

purpose. One of a number of hurricane/tropical storm hindcastwind models is applied to each of

the storms/hurricanes. These models incorporate into them such factors as the storms

maximum wind speed, the speed that the eye of the hurricane travels, radius to maximum wind

speed, and distance from the eye of the storm to the maximum wind speed. The model is used to

determine the maximum deep-water wave height and period at the outfall location for each of

the storms. After this a statistical analysis is used to determine wave heights and periods for

different return periods. The results are usually presented in tabular form that correlates

various return periods with the respective maximum wave height, wave period, standard

deviation, and probability of excedence Return periods commonly presented are for

2,5,10,20,25,50, and 100 years.

Now the person designing the submarine outfall must use the derived design wave to determine

the Hydrodynamic forces that this wave will cause to be exerted on the outfall. The first step is to

determine the maximum velocity and maximum acceleration that the deep-water design wave

would generate at the water depths in which the outfall is to be located. The maximum velocity

is used to determine the drag force and the acceleration is used to determine the inertia force

that the design wave exerts on the outfall Pipeline as it passes over the outfall.

Entering the maximum velocity and maximum acceleration into any of several available

computer programs the maximum horizontal and maximum vertical forces exerted by the

design wave can be calculated. It is also necessary to adjust the coefficients of these equations to

account for the angle of incidence of the design wave‟s approach to the axis of the outfall pipe.

Knowing the maximum horizontal and vertical forces to which the outfall Pipeline would be

subjected during its design life it is possible to make a decision on how to assure the stability of

the outfall. It may be necessary to bury the Marine Intake & Outfall Pipeline in the seabed to

adequately protect it. It might be feasible to fasten the outfall to the seabed with mechanical

anchors that are screwed or driven into an unconsolidated seabed. It also might be possible to

stabilize the HDPE outfall by attaching sufficiently heavy ballast anchor weights onto the HDPE

pipe to affix it to the seabed.

The outfall may be stabilized with a combination of these methods.

STABILIZING HDPE OUTFALLS WITH CONCRETE BALLAST ANCHORS (WEIGHTS)

HDPEoutfalls Pipeline stabilized by concrete ballast anchors rarely fail because the HDPE pipe

and anchors tend to settle into the scour excavation without causing breakage of the pipe thanks

to the flexible characteristics of HDPE. HDPE can also tolerate movement better than almost any

other submarine pipeline material.

10.1 Determination of the spacing of anchor weights

The worst beam-stress condition usually occurs during installation and this is due to the weight

of the anchors during the floating and towing of the pipeline. It may also occur from

hydrodynamic forces due to currents and possibly from the sinking of the anchors into a soft

seabed. It is important that distances between anchor collars not be too great. The stress exerted

can be estimated as a uniformly loaded simple beam with a unit-loading equal to the unit

buoyancy of the pipe. The greatest

Stress and deflection occurs during the sinking of the Marine Intake & Outfall during the

installation on the seabed.

Determination of anchor collar weight

There are two distinct considerations in determining the amount of weight to adequately anchor

ocean outfalls of HDPE. One consideration is the ballast necessary to preclude flotation in areas

outside of the surge-surf zone, the other is to prevent movement inside the surge-surf zone

during worst expected storm conditions. Two altogether different approaches are used.

The term sink factor is used in HDPE submarine pipelines to describe the ratio of the total

downward force to the total upward force of the pipeline system including pipe, pipe contents

and anchor weights (collars). The sink factor is nothing more than the systems "specific gravity".

It is used as an indicator of the pipeline's stability and resistance to the various hydrodynamic

forces exerted by the ocean, and rules of thumb for appropriate use of sink factor values range

between.

Polyethylene pipe in soft sediment shall be secured by concrete weights or piles against flotation

with a factor of safety against uplift of 1.5.

Key design details are as follows:

• Minimum cover for all reinforcement shall be 75 mm.

• Rubber sheet 5 mm thick between block and PE pipe.

• PVC sleeves cast into blocks for connecting bolts.

• Each nut shall have a zinc nut of the same size.

• Weight blocks and collars on pipe shall be designed with a low center of

gravity to Prevent rolling and twisting of the pipe.

• Connecting bolts can be 316 SS or galvanized steel, with zinc Anodized

• Concrete used for blocks shall have minimum 28-day strength of 36 MPa.

• Typical spacing of blocks shall be 2.5 m to avoid gas pockets.

• Concrete blocks shall not extend more than 250 mm above the top of the pipe.

Ballast anchor design

Ballast anchors for HDPE submarine outfalls are usually made of reinforced concrete because of

concrete's suitable density and durability in seawater. There are many possible designs, but

generally a trapezoidal or square design is used in the open ocean so that the ballast anchor will

resist rolling when subject to lateral forces due to currents or wave action. In any case the

specific design chosen would be based on:

a) Ease of fastening the anchors to the pipeline;

b) Fasteners resistant to salt water corrosion;

c) Ease of bending and placing the reinforcing steel and:

d) Ease of casting the concrete.

particular variation uses two bolts of saltwater corrosion resistant material. It is possible to also

use fiberglass bolts, or polyethylene plastic pipe with heat formed ends as a means of fastening

the halves together.

Concrete ballast anchors may be factory cast and hauled to the outfall assembly site or cast at

the assembly site by the same labor crew to be used for installing and assembling the HDPE

outfall. Ballast anchors cast at worksite In casting the two halves of the Type A design, the form

shown in Figure 6 is usually constructed so that both halves of the collar can be cast at the same

time, using a short piece of the HDPE outfall pipe to achieve an exact fit. The two halves are

separated by 1/2 cm (1/4 inch) plywood. This provides sufficient play to insure a tight fit when

the two halves are bolted together when the anchor collar is attached to the pipe. The holes for

the bolts are formed using thin wall PVC pipe with an internal diameter 50 percent larger than

the diameter of the bolts to be used. They are held in place by a rod extending through the form

so as to help assure bolt alignment.

It is important to schedule casting of concrete anchor collars to be completed at least one month

in advance of outfall installation to allow adequate time for curing. Consideration should be

given to casting the anchor collars at the outfall shore line site to avoid unnecessary handling

and transportation.

It is also a good idea to number the matching halves when they are removed from the form

to assure compatibility of bolt holes. In any case, a little extra care in form precision will pay for

itself many times over during the attachment process.

The concrete used in the ballast weights should have a minimum cement content of 375 kg/m 3

and a 28 day strength of 300 kg/cm2 so as to be resistant to the salt water environment and

reduce the potential for corrosion of the reinforcing steel. High early strength cement may be

used to allow early removal from the forms, thus, reducing the number of forms needed over the

casting period. The type of cement used should be for marine use.

.

JOB SITE FOR BUTT FUSION AND ANCHOR COLLAR ATTACHMENT

Careful planning of the butt fusion and concrete ballast anchor attachment operations is always

necessary. The primary objective is to get the outfall constructed properly and into the water as

quickly and as easily as possible. The strategy to accomplish this should include the following

components:

a) Material storage in a convenient, easily accessibly location.

b) Adequate size and number of pieces of heavy equipment to handle material.

c) Selection of butt fusion equipment that is adequate for the diameter and DR of the outfall pipe

and which automatically records the essential details of the fusion of each joint. Experienced

fusion equipment operator will be employed for the job.

d) Protection of the butt fusion process from wind, dust, rain, snow. If necessary an enclosed or

semi-enclosed shelter for this operation will be provided. The pipe manufacturer‟s

recommendations for the fusion process will be strictly fallowed. Assure adequate time (at

least 35 seconds for each cm of diameter) for the newly fused joint to cool sufficiently before

the pipe is removed from the clamps of the fusion machine and an additional 20 minutes

before the joint is subjected to traction or flexure.

e) Adequate temporary facilities will be provided on which to fabricate the outfall Pipeline and

from which to launch the outfall Pipeline in to the ocean. The temporary facilities should be

designed to require as little motion and as little handling of materials as possible, especially the

ballast anchors.

e) The system for attaching the ballast anchors should enable the ballast anchors to be

accurately spaced at the designated intervals on the outfall Pipeline.

g) The temporary facilities should enable the completed outfall assembly to be moved into the

ocean as efficiently and quickly as possible with as little handling as possible.

h) Doing all this in a safe manner.

It will be planned to construct a temporary facility ( a small rail system) on which butt fuse and

fabricate the entire outfall with the ballasts, end plates, and pulling heads securely attached .

After pressure testing the outfall it will then pulled and towed down the rail system to launch it

into the ocean. The entire outfall will then towed into place and carefully submerged by

releasing air and allowing water to enter the outfall. It will be guided into the desired seabed

route by divers that instruct the boats for direction of pull and advise a person at the terminal

end when and how much air to release.

A variation of this method is to fabricate the outfall, with ballasts attached, in 2 or 3 long sections

and then launch the sections consecutively and butt fuse them together during the launching

process. It is important that the methodology chosen for ballast anchor installation make the job

as easy as possible.

When this method is used it is common practice to install a temporary working platform at the

waters edge so the concrete anchor collars can be attached immediately before the pipe is

dropped into the water. A gantry with block and tackle will be installed at this platform for

handling and attaching the concrete anchors. Typically a system or rollers is used to guide the

pipe from the butt fusion area to the platform and facilitate the forward movement of the butt

fusion area to the platform and facilitate the forward movement of the pipe.

TRENCHING FLOATING, SUBMERGING AND PLACING THE OUTFALL

The HDPE submarine outfall is designed to be buoyant with the anchor collars attached and the

pipe filled with air and to be strongly negatively buoyant when it is subsequently filled with

water. Air is contained in the pipe by means of a sealed and plug or plate securely attached to the

end of the pipe. The plate or plug is fitted with an air release/inlet valve and then it is attached to

the terminal end of the pipe. By gradually releasing air from this valve and allowing water to

enter the outfall at the shore end. The rate of descent is controlled through the release of air at

the terminal end and the controlled entrance of water at the shoreline. It is important that the

pipe be sunk from the shore progressing to the terminal end so as to preclude entrapment of air

in a high spot.

A number of small boats are needed to tow the pipeline out from shore as it is fused together

and the anchor collars are attached and to tow it into place for submergence. Several boats are

stationed at intervals along side the pipe on the up current side of the route pulling the pipe into

place. During the sinking, the boat at the terminal of the pipe operates the air release valve. The

boat at the terminal end of the pipe does not have to be in place until the final length is sent into

place. Three placement boats are usually required in the vicinity of the section being sunk.

It is usually easier to allow the pipe to flex with the current gradually pulling it into place along

the route as it is sunk.

Divers on the pipeline communicate with both the three or four placement boats, which are

towing the pipe into place, and the boat on the terminal end releasing the air. The divers advise

the placement boats to move the pipe to right or left, or hold, so as to keep the pipe on alignment

as it reaches the bottom and also advise the air release operator when to release the air to obtain

descent of the pipe.

Air is released in a series of short bursts with sufficient time between bursts to receive

communication from the divers. Release of the air should be controlled slowly. It should be

equivalent to the pressure of water at the depth of submergence. The end plate (or plug) must be

securely fastened to the terminal end. The pulling head should be fitted with a check valve and a

quick connect coupling to permit attachment to an air compressor if needed. It should also be

fitted with a strong, corrosion resistant air release valve of a diameter appropriate for the

diameter of Pipe. The terminal/air release boat will have a small air compressor with a hose at

least 50 percent longer that the depth of the end of the outfall to allow refloating and adjustment

if necessary.

The shoreward end of the HDPE outfall will be fitted with a butt fused flange adapter and with a

bolted plate with an air-tight gasket. It would also be fitted with a water valve of sufficient

diameter to allow water to enter the pipe at a reasonable rate for submergence of the outfall.

In addition, all boats would be fitted with two-way radios or supplied walkie-talkies.

A communication system to enable the divers to give instructions directly to the boats. All

divers would be instructed to stay above the pipe at all times. The divers would have available

several large air lift bags with lifting straps each capable of lifting 400 lbs. so, if necessary, to

make minor adjustments in the pipe without having to refloat it. There should be a sufficient

number of divers on hand to enable shifts so as to avoid the necessity for decompression,

otherwise a decompression chamber should be on hand.

Markers shall installed on the seabed along the alignment of the Outfall. And will then make a

detailed topographical survey of the seabed sufficient to define the precise profile of the Marine

Intake & Outfall. The Contractor shall make an underwater video Along the full length of the

Outfall pipeline to document seabed conditions prior to the Installation Work. The video shall

show chainagemarkers at 100 m intervals. And then second underwater video along the full

length of the installed Intake & Outfall pipeline shall be made to document seabed conditions on

completion of construction. The second video shall show the pipeline, all supports and sufficient

area of the adjacent seabed to record biological Conditions.

The as-constructed video shall be recorded soon after the Outfall is commissioned. A

photographic record and video record of the land and vegetation at the shoreline and across the

beach prior to the works commencing will be provided. A post-construction survey of the pipe

alignment using bathymetric and side-scan sonar surveys to document that the seabed has been

restored to near pre-construction Conditions will be made. Survey control will be by GPS. A

detailed survey of all works including the Outfall, diffuser, supports, piles, deaerationchamber

and other facilities will also be made. On completion of all construction, the Outfall shall be

commissioned using effluent from the treatment plant. Until commissioning, the facility shall be

maintained stop logs in the access chamber to prevent sediment, flow or material entering the

Outfall.

A commissioning plan addressing fallowing shall be Prepared.:

• Outfall conditioning to preclude internal biofouling(eg. Capped ports, fill with fresh water, or

Filtered, disinfected seawater)

• Inspections prior to commissioning

• Removal of port caps

• Assurance tests

As part of commissioning, fallowing shall be demonstrated:

• De-aeration structures operate and that air is released at

each vent • Effluent discharges from each of the ports

OPERATION & MAINTENANCE.

A long term operations and maintenance (O&M) plan shall prepare and submitted to. The O&M

plan will depend on the actual design and construction arrangements, however following

elements will be included:

• Time schedule of recommended inspection and maintenance activities for theMarineIntake &

Outfall, diffuser ports, air release points,

• The hydraulic head shall be measured continuously in the theMarine Intake & Outfall l at the

shore to allow hydraulic (conveyance capacity) evaluation and identification of any blockage or

riser damage

• Contingency plan to control biofouling

• Contingency plan to repair any damage to ports

• Procedures for diver access to the pipeline and diffuser

• Procedures for monitoring long term settlement of the pipeline

• An Outfall shutdown and re-commissioning protocol.

Organization envisaged for O&M is as fallows.

Operation Manager

Facility Supervisor

Marine Environmentologist.

Divers

Pipe Fitter

Pipe Welder

Fallowing Equipment may be required to hire as and when required.

Boat with Diving Station

Barge mounted with Crane. By: Abhay Ocean Team