B01 Attachment 9 Individual Well Drilling.pdf

Pamunkey Indian Tribe, Virginia Construction of Sanitation Facilities February 2022 Individual Well Drilling

NS-20-H29 02525 - 1

SECTION 02525

INDIVIDUAL WELL DRILLING

PART 1 - GENERAL

1.01 SUMMARY

A. This section includes drilling, casing, screening, developing and testing of water wells for individual residences.

1.02 RELATED WORK (as applicable)

A. Section 02512 – Individual Household Water Systems

B. Section 02528 – Well Abandonment

1.03 REFERENCES

A. ASTM F480 – Thermoplastic Well Casing Pipe and Couplings Made in SDR, Schedule 40 and 80

B. Virginia Administrative Code Chapter 630 – Private Well Regulations

1.04 SUBMITTALS

A. Type of drilling equipment

B. Well drilling rig operator experience and license number

C. Drilling mud and plan for use

D. Well screen and method of installation

E. Gravel, sand pack material and method of installation

F. Well casing and cap

G. Method of disinfection

H. Method of development

I. Grout and method of installation

J. Water testing lab

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K. Plan and method for hydrofracturing (if requested by the Engineer)

1.05 CONFLICTS WITH STATE WELL CODES

A. The materials and construction methods specified herein are minimum requirements. Where the appropriate state well codes require more stringent materials or execution methods, they shall apply.

B. Notify the Engineer of any planned deviation from these specifications before proceeding so any price changes, or quantity adjustments may be made.

1.06 ACCEPTANCE

A. Minimum final yield being sought is 5 gallons per minute.

B. Water shall be clear and free of sand.

C. Work covered by this section will not be accepted until records and testing connected with the work have been completed satisfactorily.

PART 2 - PRODUCTS

2.01 WELL CASING

A. Plastic Well Casing

1. Conform to ASTM F480 and be SDR 21, 200 psi manufactured of PVC 1120 or 1220 resin.

2.02 WELL SCREEN

A. General

1. Well screen openings shall be sized to permit the maximum practical sand free yield after development.

B. PVC Screen

1. Unobstructed V-type slot design with an SDR 21 rating, minimum stiffness of 170, conforming to ASTM F480.

2. Screen shall meet 1600-pound tensile pull test.

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3. Screen shall be a commercial product, equal to products manufactured by Certainteed Pipe and Plastics Group, Valley Forge, Pennsylvania.

4. Butt-type couplings shall be the same materials as the screens.

2.03 GRAVEL AND SAND PACK

A. Well rounded uniform grains of washed quartz or approved equal.

B. Weight loss by the acid test shall be less than 20%.

C. Gradation specified by the manufacturer of the well screen based on the submitted gradation of the water bearing formation or as specified by the Engineer.

2.04 GROUT

A. Conform to local or state codes

2.05 DRILLING FLUID (MUD ROTARY METHOD)

A. Conform to standard accepted well drilling practice for water wells.

2.06 HYDROFRACTURING PLAN AND METHOD

A. Conform to standard accepted well drilling practice for hydrofracturing of water wells.

B. List equipment to be used.

C. Include operating pressures and pumping capacity of equipment.

D. Plan for the hydrofracturing of the well(s) (estimated pressure, etc).

PART 3 - EXECUTION

3.01 GENERAL

A. Drill well in state permit designated location in accordance with state codes.

3.02 DRILLING

A. General

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1. State license requirements shall be met.

2. Locate all existing underground utilities.

3. Prevent contaminated water from entering the well.

4. Minimum final yield of 5 gallons per minute for the home is being sought, however, well should always be developed to its maximum yield.

a. Contact Engineer prior to abandoning wells producing less than 5 gpm.

b. If well produces less than 5 gpm and the Contractor recommends hydrofracturing the well, contact the Engineer for approval.

5. Drill and case wells at the size specified in the bid schedule.

6. If satisfactory yield and quality is obtained at a lesser depth, terminate drilling and develop at that depth.

7. Drill in accordance with local or state codes.

3.03 CASING

A. Install the materials and sizes stated on the bid schedule.

B. Install casing in wells to a depth appropriate for the formation type and minimum yield specified.

C. Finished casing height shall be 12-inches minimum above finished grade.

D. PVC casing:

1. Prevent PVC damage or scratching by properly handling PVC casing.

2. Solvent weld all PVC casing joints.

3. Follow manufacturer’s recommendation for solvent welding joints.

4. No leaks will be permitted at any joints.

E. Plumbness and Alignment

1. Maximum deviation from vertical in any 100 feet of depth is 2 1/2 inches.

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2. Conduct a straightness and alignment test on all questionable wells after casing.

a. The test will consist of running piece of pipe 40 feet long whose diameter is 1/4 to 1/2 inch smaller than the inside diameter of the inside of the of the casing to the bottom of the well.

b. No payment will be made for testing procedure or materials.

3. If the test pipe binds, is bent as a result of testing procedure or does not pass through the well casing freely the well will not be accepted and no payment will be made.

3.04 SCREENING AND GRAVEL PACK

A. Install the materials and sizes stated on the bid schedule.

B. Install PVC well screens using the open hole method.

1. Fit PVC well screen with an approved rubber type packer or by solvent welding a threaded adapter on to the PVC casing and threading the screen onto the adapter.

C. Fill the drill hole with approved material if the bottom is deeper than the screened area.

3.05 WELL DEVELOPMENT

A. Develop the well using a method that extracts the maximum practical quantity of drilling mud, fine sand, silt or other fine material.

1. Maximum allowable sands and fine material: 2 ppm (by weight).

B. Acceptable development methods include surge plungers, compressed air or high velocity jetting.

1. Bailing or pumping is not acceptable.

2. Compressed air must be delivered at a minimum rate of 75 cfm at a minimum pressure of 100 psi.

C. Conduct development so as to prevent settlement of the stratum above the water bearing formation.

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D. High velocity jetting with phosphates may be required.

1. Follow established procedures for this type of development.

E. Duration of development: one hour unless otherwise directed by the Engineer.

3.06 GROUTING

A. Conform to local or state codes.

3.07 TESTING FOR YIELD AND DRAWDOWN

A. Conform to local or state codes.

B. Test pump wells at 15 gpm or maximum well capacity, whichever is less, unless otherwise directed.

C. Do not use the actual pumps to be installed in the well for the test pump operation.

D. Duration of drawdown test: one hour, unless otherwise directed by the

Engineer.

1. Take drawdown and pump discharge measurements every 5 minutes for the first half-hour.

2. Take drawdown and pump discharge measurements every 10 minutes for the remainder of the test.

E. Record recovery measurements immediately upon completion of test pump for one hour total, unless otherwise directed by the Engineer.

1. Take recovery readings every minute for the first 10 minutes.

2. Take recovery readings every 5 minutes for the remainder of the hour.

F. Remove all temporary-pumping facilities at the conclusion of test pumping.

G. If well yield is less than 5 gpm Contact Engineer immediately.

H. Submit results of pump test to Engineer.

3.08 DISINFECTION

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A. Upon completion of test pumping and construction, thoroughly clean the well of all foreign material (i.e. cement, oil, grease, joint dope, scum, etc.)

B. Disinfect well with a chlorine solution

1. Prepare solution prior to injection into well.

2. Mix volume and strength such that a minimum concentration of 50 ppm of free residual chlorine is obtained in all parts of the well for a minimum of 24 hours after injection.

3. Flush casing above static water level with solution.

3.09 CHEMICAL AND BACTERIOLOGICAL ANALYSIS

A. Take bacteriological and chemical samples immediately after disinfection and flushing of each well.

B. Submit samples to State Department of Health approved lab.

1. Provide copy of results within 10 days of receipt of the report.

2. If a sample tests positive, notify Engineer immediately and repeat chlorination of the well until a sample tests negative.

3. Conform to sampling and preservation requirements of laboratory.

4. Parameters to be analyzed shall include all testing required by the State of

Virginia for the development of private wells. The tests shall include, at a minimum:

1. Bacteriological 6. Nitrate Nitrogen

2. Total Hardness 7. Nitrite Nitrogen

3. Total Iron 8. Chloride

4. Manganese 9. Lead

5. Arsenic 10. pH

C. Submit chemical analysis results to Engineer within 30 days of completion of test pumping.

3.10 CAPPING

A. Conform to requirements of Section 02512 for well cap.

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B. Temporary caps may be used, as approved by the Engineer, if individual water system is being completed at a later date. Caps shall prevent contamination of well by surface water.

3.11 WELL LOG

A. Keep daily log of each hole drilled.

B. File an official construction report, using state approved form, with the designated state agency within 30 days from when well is completed.

1. Submit a copy to the Engineer.

3.12 UNACCEPTED DRILLED WELLS

A. Drilled wells will not be accepted due to insufficient capacity, unsatisfactory chemical or bacteriological quality, poor alignment, loss of tools or any other cause.

B. Obtain Engineer’s approval prior to abandoning wells.

C. Well abandonment shall be in accordance with Section 02528.

END OF SECTION