departm ent of t he army u orps of s hanistan · pdf filepamir geotechnical services company...

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Afghanistan National Police (ANP UP DHQ) Water Well in Mazar‐e‐Sharif, Balkh Province

1. General:

According to project document the population of ANP UP DHQ project is 120 people and water well

(s) should fulfill the project demand, Water well drilling procedure and water well demand described

generally at below

2. Water Demand:

Average Daily Demand is derived from 155 LPCD which is given in RFP and other calculations are

outline in below:

Population = 120 Person

Capacity Factor = 1.5

ADD = LPCD 155

ADD=120*155=18600*1.5=27900 liter=27.9 m3

Average Daily Demand per Day 27.9 m3

Or with 16 hours pumping: 27900/16=1743.75 liter/hour=29.06 liter/min=0.48 liter/second

3. Well Drilling Method:

Water well will be drilled with mud rotary Method

Mud rotary machine


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4. Depth and Diameter of well:

Depth of the well will be about 70 meters and can change according to underground layers

conditions, diameter of the drilling will be 14 inches.

5. Sampling:

For water well design and preparation of geologic log, soil samples will be taken from every meter

and also water sample will take for water quality analysis

5.1 Water Sampling:

Water sample will be taken at final step of pumping test, water sample will analyze for physical,

chemical and bacteriological in certified laboratory because this sample will be a good

representative sample from condition of underground water quality

5.2 Soil Sampling:

Soil samples will be taken meter by meter for sieve analyses, preparation of water well geological log

and water well designing.

Washed (grab) samples every meters depth during well drilling


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6. Laboratory Testing:

Taken soil samples from water well will be transferred to Pamir geotechnical laboratory for sieve

analyzing. Using the results of the sieve analysis for the finest aquifer material, plot the cumulative

percent of the aquifer material retained versus the size of the mesh for each sieve. Fit a smooth

curve to these points. Find the size corresponding to a 70 percent cumulative retention of aquifer

material.

6.1. Aperture size:

The well screen aperture opening, called slot size is selected based on sieve analysis data of the

aquifer material. For a homogeneous formation, the slot size is selected as one that will retain 40 to

50 percent of the sand. Use 40 percent where the water is not particularly corrosive and a reliable

sample is obtained. Use 50 percent where water is very corrosive and/or the sample may be

questionable. Where a formation to be screened has layers of differing grain sizes and graduations,

multiple screen slot sizes may be used. Where fine sand overlies a coarser material, extend the fine

slot size at least 3 feet into the coarser material. This reduces the possibility that slumping of the

lower material will allow finer sand to enter the coarse screen.

6.2. Filter Packing:

For a filter packed well, the screen should retain 90 to 100 percent of the filter material (AED Design

Requirements, Well Pumps & Well Design, November 2009). Filter packing or gravel packing is

primarily sand placed around the well screen to stabilize the aquifer and provide a radius of high

permeability around the screen. The best material is coarse silica sand and fine gravel material which

is usually found in river‐beds or ocean beaches.

6.2.1. Size:

Grain size of the filter pack will be selected on the basis of information obtained from sieve analyses

of the material in the aquifer. The well screen aperture size will be selected so that between 85 and

100 percent of the filter pack is larger than the screen openings. (Will use from multiply between 4

to 6 according to aquifer material uniformity or use 9 if formation includes silt), AED Design

Requirements, Well Pumps & Well Design, November 2009.


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6.2.2. Thickness:

The thickness of the filter pack will range from a minimum of 50 mm (2 in) to approximately 150

mm (6 inches). A filter envelope thicker than about 150 mm (6 inches) will not greatly improve yield

and can adversely affect removal of fines, at the aquifer‐filter pack interface, during well

development.

6.2.3. Filter Pack length:

The gravel pack shall be 1.5 times the length of the screen section it surrounds. For example if the

screen is 3 meters in length the gravel pack shall be 4.5 meters in length straddling the screen on the

top and bottom. (AED Design Requirements, Well Pumps & Well Design, November 2009)

7. Well log:

According to soil samples taken from water well during the drilling, well log should be prepared.

Litho logy, depth and thickness of water bearing strata and non aquifer layers should be determined

in the borehole log.

8. Well installation design:

Well installation design should be prepared basis on the samples sieve analyses results, borehole

geologic log, slot size design, screen and selected gravel pack materials. Screens and casing

situations diameter, class, schedule, manufactory, slot size opening, filter gravel pack material

diameter and situation, seal block positions, will be determined. Centralizer's situations and static

water level also should be determined in the well installation design.

9. Casing and screen installation:

For this water well we will 6 inches PVC screen Schedule80 (according to AED design requirement for

water well pumps and well design, November 2009) and according to well design, approved casing ,

screen, gravel pack material will be installed. However, according to well depth and calculated water

pressure, our proposed casing and screen will submit. The well casing should extend at least 500 mm

(20 in) above the level of the concrete surface slab in order to provide ample space for a tight

surface seal at the top of the casing.


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10. Centralizers:

Centralizers are very important when installing casing since slots in the well screen may become

severely blocked with clay if the screen rubs hard against the borehole wall while it is being inserted

into the borehole. Centralizers also ensure that there is even distribution of cement grout and filter

pack. This is really important since if the screen is placed against the borehole wall, the well may

always produce turbid water! Centralizers can be made from PVC casing, flexible green wood or 1.2

cm (0.5 in) wide iron straps (see below figure). In this well we will be used PVC centralizers every 25

meters.

Installation of Iron Strap Centralizer

11. Filter Volume:

Calculate the volume of filter material necessary to fill the well annulus to 2 meters above the top of

the well screen ‐ this allows for areas of borehole washout to be filled without exposing the upper


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screen to formation stabilizer or borehole fines. After the filter pack is installed, place of filter pack

must check before and after of well development and must be according to approved well design.

12. Sealing:

After installation of casing, screen and filter gravel pack, we can seal with clay sealing some parts of

well for prevent of surface and also bad quality waters that have influence to quality of water well.

Length of clay sealing should be at least 3 meter on top of filter pack materials.

13. Top concrete pad:

After installation of casing, screen, filter gravel pack and sealing fill the top 3 m of annular space with

a formation seal that extends up to ground level. The sealant will be cement grout. The formation

seal must be effectively placed to prevent contaminated surface run‐off from infiltrating into the

well.

14. Well development (Air compressor Method):

Compressed air will be used to develop wells at unconsolidated formations. Well developing by air

compressing method will perform to maximize yield, minimize turbidity, and remove any remaining

drill cuttings, drill mud and fluids and continued until the well produced clear, sediment free water.

We will do air compressing to obtain acceptable water (Clear water).

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pumped to point of discharge, and equipment necessary for measuring the rate of flow and water

level in the well. An 8 hours step‐drawdown capacity test shall be run with the pumping rate and

drawdown at the pump well; during the step drawdown test the pumping rate shall be increased in

steps at 2 hours intervals. Specific capacity shall be measured for each step. The well shall be "step"

tested at rates of approximately 1/2, 3/4, 1 and 1.1/2 times the design capacity. When the pump is

shut off, water level reading shall be taken during the rebound period for the same interval of time

as the drawdown test (AED Design Requirements, Well Pumps & Well Design, November 2009).


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Step drawdown pumping test form (step 1 of 4)


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17. Water quality testing:

If the capacity test indicates that the required capacity can be obtained, the tests for quality of water

shall be made, water sample will be taken from last stage of pumping test will test , and will be

analyzed by a certified laboratory for chemical, physical and bacteriological characteristics, results

and recommendation will be reported.

18. Final well construction report:

We will submit a final report for the well from all well construction steps and results.

19. Well Decommissioning/ Abandonment:

If the well disapproved by the Contracting Officer, or any well decommissioned/abandoned by the

Contractor for any reason shall be decommissioned/abandoned.

Well decommissioning/abandonment includes the removal of all materials left in the well, excluding

the filter pack, and including backfill materials, casing, screen, and any other material placed into the

hole before the decision was made to abandon the well. Test holes decommissioned/abandoned for

any reason shall be grouted (cement and bentonite grout according to project sow) from the bottom

to within 80 mm of the top of the ground surface; the top 80 mm shall be backfilled with material

appropriate for the intended land use.


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DRILLING LOG FORM Project Name: Location: Coordinate: Water Well Drilling Method and Diameter: Site Engineer: Water well Driller:

Sheet No: Date and time Depth (m) Soil Spec Bit Diameter Remarks


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CONSTANT PUMPING TEST FORM Project: ANP UP DHQ Site: Mazar-e-Sharif Shahi District, Balkh Province Well: water well Coordinates: Screen Setting (m below ground surface ): Description of Measuring Point: Height of Measuring Point (m): Measured With: Static Water Level (m below measuring point): Drawdown: Start Time/Date: Discharge Rate(lps): Pump Kind: Pump Situation:

Time

Elapsed Time

(minutes) Depth to Water (m bmp) Drawdown (m)

Q (lps) Comments

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19


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20 22 24 26 28 30 35 40 45 50 55 1 hr 60 70 80 90 100 110 2 hr 120 150 3 hr 180 210 4 hr 240 270 5 hr 300 330 6 hr 360


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RECOVERY FORM Project: ANP, UP DHQ Site: Mazar-e-Sharif District, Balkh Province Well: water well Coordinates: Screen Setting (m below ground surface ): Description of Measuring Point: Height of Measuring Point (m): Measured With: Static Water Level (m below measuring point): Drawdown: Start Time/Date: Discharge Rate(lps): Pump Kind: Pump Situation:

Time

Time Since Pumping

Started t in minutes)

Time Since Pumping

Stopped t' in minutes) t/t'

Depth to Water (m bmp) Residual Drawdown (m)

1440 0 Inf. 1440.5 0.5 2881 1441 1 1441 1441.5 1.5 961 1442 2 721 1442.5 2.5 577 1443 3 481 1443.5 3.5 412 1444 4 361 1444.5 4.5 321 1445 5 289 1446 6 241 1447 7 207 1448 8 181 1449 9 161 1450 10 145 1451 11 132 1452 12 121 1453 13 112 1454 14 104 1455 15 97 1456 16 91 1457 17 86 1458 18 81 1459 19 77 1460 20 73 1462 22 66


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1464 24 61 1466 26 56 1468 28 52 1470 30 49 1475 35 42 1480 40 37 1485 45 33 1490 50 30 1495 55 27 1 hr 1500 60 25 1510 70 22 1520 80 19 1530 90 17 1540 100 15 1550 110 14 2 hr 1560 120 13 1590 150 11 3 hr 1620 180 9 1650 210 8 4 hr 1680 240 7 1710 270 6 5 hr 1740 300 6 1770 330 5 6 hr 1800 360 5 1830 390 5 7 hr 1860 420 4 1890 450 4 8 hr 1920 480 4 9 hr 1980 540 4 10 hr 2040 600 3 11 nr 2100 660 3 12 hr 2160 720 3 13 hr 2220 780 3 14 hr 2280 840 3 15 hr 2340 900 3 16 hr 2400 960 3 17 hr 2460 1020 2 18 hr 2520 1080 2 19 hr 2580 1140 2 20 hr 2640 1200 2 21 hr 2700 1260 2 22 hr 2760 1320 2 23 hr 2820 1380 2 24 hr 2880 1440 2


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Project: Well Number: Location: Recorded By: Date of development: Development Criteria: Hole Diameter: Casing Diameter: Depth To water: Depth To Base of Screen: Screen Placement:

Well Development Record

Date Starrt Time Finish Time Water Removed (Liter) Water Charcteristic Comments

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