G. Water_Supply_Well.pdf

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Water Supply Well

SECTION 02521

WATER SUPPLY WELL

PART 1 � GENERAL

1.01 DESCRIPTION

A. This section specifies the completion of one potable water well drilling, 6 inch casing, development, and test pumping, including all materials, labor, and incidentals.

1.02 SUMMARY

A. The government estimates the depth of well at Ditch Creek to be 150 feet to obtain the desired sustained well production rate of 15 gallons per minute with drinking water quality.

B. The government estimates the depth of well at Ollokot Campground to be 150 feet to sustain a well production rate of 5 gallons per minute for drinking water from a hand pump or small pump.

C. The placement of the well will be approved by the Contracting Officer prior to drilling.

D. The maximum drilling depth shall be 200-feet unless ordered otherwise by the Contracting

Officer. Drilling progress shall be reviewed at 20-foot increments below 80 feet to determine if work should proceed. Any useable water bearing zones shall be fully developed only after the approval of the Contracting Officer.

1.03 REFERENCES

A. Administrative Rules for Well Construction Standards, issued by the Oregon Water

Resources Board; latest edition.

B. American Water Works Association (AWWA), Standard for Water Wells (A100-06).

C. American Water Works Association (AWWA), Field Welding of Steel Water Pipe (C206-

03).

D. American Society for Testing and Materials (ASTM), Pipe, Steel, Black, Welded and

Seamless (A 53 1999).

E. American Society for Testing and Materials (ASTM), Thermoplastic Well Casing Pipe and

Couplings Made in Standard Dimension Ratios (SDR), SCH 80 (F 480 1995).

1.04 QUALITY ASSURANCE

A. All well work shall comply with the provisions of this specification and the most recent editions of the References listed in 1.03.

B. Well Driller Qualifications: An experienced water supply well driller licensed in Oregon available for review upon request by Contracting Officer.

C. This specification by no means shall over ride the Oregon State Regulations. If for some reason there is a conflict between these specifications and the Oregon State regulations, the

Contractor shall notify the Contracting Officer before construction begins.

D. The Contractor shall take such precautions as are necessary or as may be required to permanently prevent contaminated water or water having undesirable physical or chemical characteristics from entering the well. Contractor shall also take all necessary precautions during construction to prevent contaminated water, gasoline, or any other contaminant from

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Contractor-caused contamination shall be cleaned up completely by the Contractor.

E. In the event that the well becomes contaminated or that water having undesirable physical or chemical characteristics enters the well because of the neglect of the Contractor, Contractor shall, at Contractor's own expense, perform such work and supply such casings, seals, sterilizing agents or other material as may be necessary to eliminate the contamination or shut off the undesirable water.

1.05 WELL DRILLING PERMIT

A. The contractor is responsible for obtaining and paying for a valid well drilling permit from the Oregon State Water Resources Department. The Government will obtain and pay for the permit from the Department of Human Services Drinking Water Program for water system modifications.

1.06 SUBMITTALS

A. Submit a Well Installation Plan 10 business days prior to beginning drilling operations.

Mobilization activities may start prior to submittal of the plan. The plan shall be approved and signed by an officer (or owner) of the well drilling company. The following requirements shall be incorporated into the Contractor’s Well Installation Plan and followed in the field. The plan shall include but shall not be limited to, a discussion of the following:

1. Description of well drilling methods, and installation procedures, including any temporary casing used.

2. Drill cuttings and fluids disposal

B. Submit sufficient product information for all products described within these specifications.

C. Submit any soil samples, sieve analysis results, Well Screen product, well screen recommendation (opening, length, installation well depth, etc.), well pumping results, and testing results to the Contracting Officer.

D. Submit one copy of the State Well Drillers Report to the CONTRACTING OFFICER within

15-days of well completion.

E. Submit one copy of the water quality test results within 5-days of receipt from the laboratory.

1.PART 2 � PRODUCTS

2.01 MATERIALS

A. Casing and Couplings

1. Steel casing shall be new black steel pipe, 6 inch nominal inside diameter, conforming to ASTM A 53, STD weight, Schedule 40.

2. Section lengths shall be 5 feet minimum.

3. Joints shall be field welded in accordance with AWWA C206.

B. Cement and Bentonite Grout and Bentonite Seals

1. Per State of Oregon, Administrative Rules for Well Construction Standards

C. Disinfecting Solutions

1. Domestic laundry bleaches containing sodium hypochlorite or calcium hypochlorite in powder or tablet form. Do not use bleach with added fragrance.

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D. Drilling Fluids.

1. The Contracting Officer must approve in advance the use of any drilling fluids. Submit manufacturer’s data on any drilling fluids proposed for use. Bentonite may not be used.

E. Drilling Water

1. Suitable for domestic consumption.

F. Filter Pack (Optional bid item)

1. Filter pack material, when required by the Contracting Officer or Administrative Rules for Well Construction Standards shall be a product of a commercial sand and gravel supplier, and shall be properly sized and graded for the surrounding soil encountered, and shall be composed of clean, round, hard, water-worn siliceous material, free of flat or elongated pieces, organic matter, or other foreign matter. The filter material shall be of a size, which will allow the maximum flow of water into the well and prevent the infiltration of sand and silt.

G. Sanitary Well Seal

1. The sanitary well seal shall be constructed as required by the State of Oregon, Administrative Rules for Well Construction Standards, Chapter 690, Division 210. The casing will be sealed with a welded 3/16 inch thick plate steel cap 1/2 inch larger than the diameter of the casing.

H. Slotted Well Liner (Optional bid item)

1. 4½" PVC slotted pipe, SDR 26, or approved equal.

I. Soil Sample Containers

1. Resealable bags, or plastic or waxed cardboard containers with sealing lid; 1 quart in size.

J. Well Liner (Optional bid item)

1. 4½" PVC slotted pipe, SDR 26, or approved equal.

K. Well Screen (Optional bid item)

1. Construction

a. Continuous slot type with closed, bail bottom.

b. Field constructed screen is not acceptable.

2. Material

a. Screen shall be constructed of one of the following.

1) Stainless Steel - ASTM A240 Type 304.

2) Stainless Steel - ASTM A240 Type 304 L.

3) Stainless Steel - ASTM A240 Type 316.

3. Diameter

a. Telescopic size to fit casing in which it is to be installed.

4. Slot Size and Length.

a. Manufacturer’s standard, slot size to be determined by the Contracting Officer.

5. Packer

a. Self-sealing, stainless steel using a V-shape, flexible neoprene ring, and mounted on heavy metal ring which can be threaded or welded to top of screen.

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2.PART 3 � EXECUTION

3.01 PREPARATION

A. Exercise precautions to prevent foreign materials and surface water from entering drilled hole.

B. The Contractor shall protect the adjacent terrain and surface water from siltation and contamination. Construct a settling basin to contain the drilling fluid, cuttings and compounds and provide a means to filter sediment prior to discharging excess water.

3.02 DRILLING METHOD

A. Drill well using the cable tool or air rotary drilling method.

3.03 INSTALLATION

A. Temporary Surface Casing

1. The use of a drive shoe is at the Contractor's option. Furnish and install a temporary casing that is four inches larger in diameter than the permanent casing. The temporary casing shall extend a minimum of 18 feet below the ground surface and to an additional depth as applicable:

a. If drill hole passes though a sound, uncreviced, consolidated rock formation, case 5 feet (minimum) into the rock formation.

b. If drill hole passes through unconsolidated formations and no clay lenses, case 5 feet (minimum) below the static water level.

c. If drill hole passes through unconsolidated formation with a clay layer at least 6 feet thick, case 5 feet (minimum) into the clay layer.

2. Remove all temporary casing while the surface seal is being placed.

B. Plumbness and Alignment

1. Drill as near vertical as possible. The axis of the well hole shall not deviate from vertical by more than 2/3 of the smallest casing inside diameter for each 100 feet of depth.

C. Grouting

1. Utilize cement grout to shut off unsatisfactory water horizons or to stabilize caving formations. Place grout utilizing a grout pump and tremie.

A. Minimum Length of Permanent Casing

1. The permanent well casing shall extend from 18 inches above the ground surface to the bottom of the hole. Excess casing can be cut off to meet the proper height constraints when the pump is installed.

B. Grout Surface Seal

2. Construct the grout surface seal in the presence of the CO, or designated Government representative.

3. The annular space between the permanent well casing and the drill hole shall be completely filled and sealed with cement grout to comply with applicable State regulations and the following:

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a. Diameter of upper drill hole: Drill the annular space a minimum of 4 inches in diameter larger than the nominal diameter of the permanent well casing and at least 18 feet below the ground surface.

4. Temporary Surface Casing Removal

a. Remove all temporary surface casing necessary to support the walls of the larger well bore while placing the grout surface seal.

5. Grout Surface Seal Placement

a. Construct grout surface seal by placing or forcing grout from the bottom upward between the permanent casing and the open hole or temporary surface casing.

b. Slowly remove the temporary surface casing as the annular space is filled with grout.

Alternately, the temporary surface casing may be removed immediately after the grout has been placed, but not later than 1/2 hour after initial introduction of grout into the hole.

c. Complete the surface seal by topping off the fresh grout after settlement occurs and within

1/2 hour after initial placement of the grout surface seal.

C. Permanent Casing Installation

6. The use of a drive shoe is at the Contractor's option. Center the permanent casing in the temporary casing using mechanical spacers to form an annular space for the surface seal.

7. Terminate the top of the permanent casing so that it will be 24 inches (minimum) above the ground surface and install a water tight cap. The permanent casing shall extend 18 feet (minimum) below the ground surface and to an additional depth as applicable:

a. If drill hole passes though a sound, uncreviced, consolidated rock formation, case 5 feet (minimum) into the rock formation.

b. If drill hole passes through unconsolidated formations and no clay lenses, case a 5 feet (minimum) below the static water level.

c. If drill hole passes through an unconsolidated formation with a clay layer at least 6 feet thick, case 5 feet (minimum) into the clay layer.

d. In unconsolidated formations connect the well screen to the bottom of the permanent casing at the water bearing formation.

8. Joints.

a. Weld casing segments to form continuous, watertight casing in area to be cased. Prepare and weld casing as follows:

1) Cut casing ends square.

2) Bevel end to be joined.

3) Align casing segments.

b. Join segments together using electric arc welder. Use sufficient number of passes to completely fill slot formed. Proportion placing of weld material to provide a minimum of

3 full passes within the slot area. Remove slag from welded area between passes.

D. Perforating.

9. Perforation Placement.

a. CO will determine depth and length of perforated segment with recommendations from the well driller.

10. Perforate casing in place in the hole.

11. Demonstrate perforator on casing in the hole above the cut-off line.

a. Perforator Type.

1) Holte Manufacturing Casing Perforator producing slots 1/8 by 1 inch long; or other approved method.

E. Capping.

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12. Upon completion of well, weld a 3/16 inch steel plate, approximately 1/2 inch larger in diameter than casing OD, over the cut off casing top. Spot weld in 4 places around casing so no holes larger than 1/16 inch are present.

3.04 FIELD QUALITY CONTROL

F. Test Equipment.

13. Provide the following equipment for the test:

a. A 10-foot long plummet of 5” well casing, with a support ring or hook on one end.

G. Plumbness and Alignment

14. Plumbness and alignment shall be in accordance with ANSI/AWWA A100 and approved by the CO.

H. Sampling of Penetrated Material.

15. Sampling Interval.

a. Sample at every change of material or at 25 foot intervals within the same material.

3.05 WELL DEVELOPMENT

I. Develop well by either of the following methods:

16. Development by Surging.

a. After the casing has been perforated, develop well by surging unless other methods are approved in writing by the CO.

b. Do not use surge block opposite casing perforations. Surge by natural drilling action of the drilling machine. Start surging at a slow rate and gradually progress to a maximum rate. Continue surging until no more fines can be brought into the well or until ordered to stop by the CO.

c. Continue well development until water from well is clear and free of fines.

17. Development by Air Jetting.

a. Development of completed well performed by air jetting method. Development shall start at the bottom of the perforations gradually working toward the top, so that all fines are pulled through the perforations and forced out of the well.

Continue development (may require more than 1 pass) until no more fines can be brought into the well or until ordered to stop by the CO.

3.06 CLEANING AND DISINFECTION.

J. Clean and disinfect the well upon completion of well development. Disinfection may be done prior to pump test.

18. Cleaning.

a. Thoroughly clean the well by removing all foreign substances and if required, swab with alkalis to remove oil and grease.

19. Disinfection.

a. After cleaning, disinfect the well with chlorine solution of sufficient strength to provide a

50 mg/l chlorine residual in all parts of well.

b. Disinfect as follows:

1) Dump concentrated chlorine solution into well.

2) Agitate well water from top to bottom with a bailer or other method approved by COR for at least 30 minutes.

3) After agitating, wash the walls of the casing above water level thoroughly with water bailed from the well.

4) Leave chlorine solution in the well for a period of at least 12 hours.

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5) Test chlorine residual. If less than 10 mg/l remain, repeat disinfection process.

6) After disinfection, pump well at desired yield for a minimum of 30 minutes, or until no chlorine residual remains.

3.07 PUMP TEST

K. Well yield pump tests, draw down, and recovery readings shall be performed in the presence of the CO. All equipment must be in good condition and assembled in good working order prior to beginning tests.

L. Forced air or bailer methods may be used for the 4 hour tests. Use a temporary submersible pump in well for the 8-hour test.

M. Unless otherwise ordered by the CO, set the pump intake at the bottom-most water bearing zone and two feet above the top of the well screen. The pump shall be able to pump 60 gpm with the level of draw down within 1 foot of the pump. Regulate the flow with a throttling valve.

N. Flows shall be measured using a flow pipe with calibrated flow orifice and applicable calibration sheet.

O. Draw down measuring equipment shall be installed in the well and checked prior to starting a test. Draw down shall be measured with air line or electrical probe methods.

P. The Contractor shall record the test measurements and other pertinent data.

Q. Water pumped from the well shall not be circulated back into the well. Provide lead off pipes and settling ponds as needed to protect the surrounding area from erosion due to pumping tests.

R. Conduct the well yield tests as follows:

20. Let well stand idle for 12 hours prior to start of pumping.

21. Record clock time for each measurement taken.

22. Measure the static water level in well.

23. Measure the water temperature from the well at the beginning, midpoint and end of each test.

24. Pump well at 10 gpm. Pumping shall be continuous and uniform throughout each test phase.

25. Measure and record yield (gpm), draw down, and clock time as follows:

a. First five minutes, readings at one-minute intervals.

b. Next ten minutes, readings at two-minute intervals.

c. Remainder of first hour, readings at five-minute intervals.

d. After first hour until the fourth hour, readings at 15 minute intervals.

e. If the test is the final 8-hour test, readings at 30 minute intervals for the balance of

8 hours.

f. After the initial pumping rate has been in effect for at least one hour, AND the draw down has remained static for at least ½ hour; increase the pumping rate of wells as follows until 30 percent of the original water depth remains above the lowest water bearing formation.

1) Increase pumping rate in proportion to the original static water depth and desired increase in draw down.

g. When pumping has stopped, immediately record the clock time and draw down in the well, and measure well recovery rate as follows (or until prior pumping levels are achieved):

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1) First five minutes, readings at one-minute intervals

2) Next ten minutes, readings at two-minute intervals

3) Remainder of first hour, readings at five-minute intervals

Or as otherwise directed by CO.

3.08 WATER ANALYSIS

S. After the pump test is completed, the Contractor shall obtain samples of the well water in approved containers for physical, biological and chemical analysis and submit these samples for analysis to the State or to a State approved commercial laboratory as required by OAR

333-61-030 (1) and OAR 333-61-030(6).

T. Testing shall include at a minimum the parameters: (1) total coliforms and turbidity, (2) the inorganics barium, chromium, copper, lead, nitrate (measured as nitrogen), nitrite (measured as nitrogen), and selenium, and (3) the secondary drinking water contaminants aluminum, chloride, color, copper, corrosivity, fluoride, foaming agents, iron, manganese, odor, pH, silver, sulfate, total dissolved solids and zinc, at the end of the pump test.

3.09 WELL LOG

A. The Contractor shall submit a complete log to the Contracting Officer setting forth the following:

1. The reference point for all depth measurements.

2. The depth at which each change of formation occurs.

3. The identification of the material of which each formation is composed.

4. The depth interval from which the water sample is taken.

5. The depth at which hole diameters (bit sizes) change.

7. The total depth of completed well.

8. The depth of intermediate and/or surface seals, as applicable.

9. The amount of sealing material (number of sacks) placed for each seal, as applicable.

10. The depth and description of the well casing.

11. The description and location of the well screen.

12. The sealing off of water-bearing or undesirable formations, if any, and the exact location of such seals.

3.10 WELL ABANDONMENT

A. If the CO orders a well be abandoned, plug the well in accordance with State of Oregon regulations (OAR 690, Division 220 – ABANDONMENT OF WELLS) to within five feet of the finish grade as the casing is removed. Fill the remaining hole with native topsoil. Take necessary actions in making the area look undisturbed.

3.11 STOP WORK

A. If work is stopped or delayed for an extended period of time, the Contractor shall clean up the site as determined by the C.O.

END OF SECTION