C04_Att. 3 - Terrytown Specifications.docx

General Specifications

0. Contractor shall be licensed by the State of Colorado and follow the rules of The Division of Water Resources (DWR) and the Board of Examiners of Water Well Construction and Pump Installation Contractors.

0. Contractor shall meet the minimum requirements of "Rules and Regulations for Water Well Construction, Pump Installation, Cistern Installation, and Monitoring and Observation Well/Hole Construction" 2 CCR 404-2.

0. Contractor shall adhere to requirements of “Rules and Regulations for Administration of Licensing, Financial Responsibility, Continuing Education and Remedial Action for Well Construction and Pump Installation Contractors" 2 CCR 402-14.

0. Well location shall be staked by CO and the depth needed shall be a minimum of 100’ and maintain a minimum of 10 gallons per minute (gpm) production rate to accommodate the site. The well shall be a minimum of 100 feet to avoid the interaction and influence of surface water.

0. As a part of the project the well shall be pump tested and the production rate, raw water quality determined, and a well log provided. At minimum an 8-hour pump test shall be included. The raw water quality testing shall at minimum include bacteriological, radionuclides, arsenic, and metals in the results. This information is to be supplied upon completion of drilling the well.

0. After drilling and testing is complete and necessary well implements are installed, the well shall be capped with hand pump so that the well pump, head, and distribution lines can be installed after the well production rate, draw down, and chemistry is determined.

0. The completed well shall include a well cap, casing, pitless adapter, bentonite grout, well screen and gravel pack. Well pump, drop pipe and distribution line are not included in this project.

0. Well hand pump shall be installed on the new well for immediate use after testing.

0. All drill castings, waste material, and surface disturbance restored to original condition within 5 business days of completion of drilling work.

0. Pitless adapter outlet shall be 1-1/2” diameter and 7’ below finish grade. The pitless adapter shall be protected and backfilled for later excavation to install distribution lines.

SECTION 01600 – WATER AND WELL TESTING.

PART 1 - GENERAL

A. SUMMARY

Applies to testing of the water and well prior to construction at the site.

B. INSPECTION

The Contractor shall report findings required below the Contracting Officer (CO) and allow 15 calendar days for the Government to either allow the contractor to proceed in writing or make changes to the Contract in writing before proceeding with construction.

C. TESTING LAB

The Contractor shall use a Colorado Certified Laboratory for testing as approved by Colorado Department of Health and Environment.

D. WATER TESTING SHALL CONFORM TO 5 CCR 1002-11 COLORADO PRIMARY DRINKING WATER REGULATIONS.

Contractor must meet Colorado regulations for water testing and conform to water operator practices when testing drinking water.

Opening well and work in around well must be performed by a contractor licensed in pumps and wells by Colorado Division of Natural Resources.

PART 2 – PRODUCTS

A. TESTING MATERIALS

Contractor shall provide testing materials and follow CDPHE practices.

PART 3 – EXECUTION

A. GENERAL- ITEMS TO BE TESTED

1. Well Depth

2. Well screen depth

3. Static water level in well

4. Well pump type and condition

5. Well performance as detailed in Section 15300, Subsection 3.5 - Performance Test

6. Water quality as detailed in Section 15300, Subsection 3.7 - Water Samples and Testing

SECTION 15300

POTABLE WATER WELL

PART 1 - GENERAL

1.1 DESCRIPTION

A. The work of this Section consists of drilling, casing, well screen, grouting, development, testing, disinfecting, water sampling and testing, capping, and completing records for a potable water well. If the production and water quality tests meet the requirements set forth in this specification, the well is deemed favorable.

B. Well shall be minimum 100' deep.

1.2 WORK

A. The Contractor shall furnish all labor, materials, equipment, and other incidentals necessary to successfully complete each item of work and carry out all duties and obligations imposed by the contract.

1.3 SUBMITTALS

A. The Contractor shall submit to the CO all laboratory test results and standard forms specified in this section.

B. Hand Pump product and specifications shall be submitted to CO prior to ordering.

PART 2 – PRODUCTS

2.1 CASING

A. Steel Casing: New 6-inch I.D. Minimum wall thickness 0.250, black steel casing complying with ASTM A-53, in minimum lengths of five feet. Steel casing shall be joined by welding two full electric arc passes.

B. Polyvinyl Chloride (PVC) Casing: New, 6-inch, Sch 40, minimum wall thickness

0.237 inches, PVC casing complying with either ASTM D-2241 or ASTM F-480. All joints shall be solvent weld.

C. Pitless Adapter NFS approved 1-1/2” pitless adapter at 7’ below grade.

2.2 WELL SCREEN

A. PVC well screen shall be used.

B. The screen aperture size shall be recommended by the Contractor and approved by the CO, based on soil properties encountered.

C. Screen surface exposed to the aquifer shall be 10-feet long.

D. Screen size and screen length shall be based on the type of aquifer and formation encountered. The CO shall approve the Contractor's choice of screen prior to installation.

E. When an artificial filter is required, the Contractor shall select a screen/slot aperture size, which is compatible with the artificial filter. The screen aperture openings shall be sized to pass not more than 15 percent of the artificial filter material.

F. Perforated pipe, in lieu of a screen, will not be approved.

2.3 DRILLING WATER

A. Drilling water shall meet potable water standards.

2.4 DRILLING FLUID

A. Drilling fluid shall consist of drill water and/or an approved commercial agent. Toxic and/or dangerous substances shall not be added to the drilling fluid.

B. Bentonite or other mudding agents having a cementious character shall be approved by the CO prior to use.

2.5 COUPLINGS

A. Threaded stainless steel couplings.

2.6 CEMENT GROUT

A. Grout shall be a mixture of Portland cement and water.

B. Portland cement shall be Type I or III complying with ASTM C-150.

C. Water/cement ratio shall be 6 gallons of water to each 94-pound bag of cement.

2.7 SANITARY WELL CAP/HAND PUMP

A. Aluminum, watertight cap with screened vent, and connection for galvanized rigid conduit (GRC), sized for well surface casing. The cap shall be bolted to the outside of the casing. And/or integrated Hand Pump made by Simple Pump or approved equal.

2.8 DISINFECTANT

A. Chlorine or other disinfectants, approved by the CO shall be used. The disinfectant shall be delivered to the jobsite in original closed containers bearing the original label indicating the percentage of available chlorine.

15300 - 2

POTABLE WATER WELL

PART 3 - EXECUTION

3.1 WELL CONSTRUCTION

A. The method of drilling the well, installing the casing, placing casing backfill, and grouting shall be proposed by the Contractor and approved by the CO prior to work. The method, however, shall be consistent with standard well drilling practices for potable water wells, these specifications and the State of Colorado Rules and Regulations for Water Well Construction, Pump Installation, and Monitoring and Observation Hole/Well Construction, latest edition.

B. An annular space at least four inches larger in diameter than the permanent casing shall extend from the ground surface to the bottom of the surface grout seal specified in this section, unless otherwise approved by the CO. The Contractor may choose to install temporary casing to ensure the integrity of this space until placement of the surface grout seal is complete. Drilling for, and placement and removal of this temporary casing shall be considered subsidiary to the other work and shall not be paid separately.

C. The permanent surface casing shall be steel and extend above the finished ground elevation a minimum of 24 inches.

D. The solid casing below the surface casing shall be PVC unless method of drilling, as approved by the CO, requires steel casing. Casing below surface casing shall be proposed by the Contractor and approved by the CO prior to work.

E. The hole shall be round, plumb and true to line. The vertical alignment of the hole and permanent casing shall permit a 20-foot length of pipe, having a diameter two inches smaller than the permanent well casing, to be lowered and raised in the hole without binding.

3.2 WELL SCREEN

A. Install in accordance with manufacturer’s recommendations.

B. The screen shall be installed to prevent damage to the screen and ensure it is fully exposed to the aquifer.

C. The final connection between the casing and the well screen shall be straight, sand tight, and retain 100 percent of the screen strength.

3.3 WELL GROUTING

A. Surface Formation Seal:

1. The effective length of the surface formation seal shall not be less than 40 feet, measured vertically from the deepest limit of the seal up to the depth of frost penetration as shown on the drawings. The grout shall not extend to the ground surface.

2. A retainer, packer or plug shall be provided at the bottom of the surface seal (temporary casing) to prevent grout from falling to the bottom of the well.

B. Continuous Grouting:

1. Temporary Casing Installed

a. Grout shall be placed to completely fill the annular space between the temporary casing or open borehole and the permanent casing. The temporary casing shall be slowly removed allowing the grout to fill the area between the wall of the well and the casing.

b. Grout shall be placed in accordance with the Manual of Water Well Practices for Continuous Grouting. The tremmie method shall be used for grouting depths in excess of 27 feet.

c. Grout shall be added as needed to fill the entire void between the borehole and casing. The Contractor may choose not to install temporary casing for installation of the grout seal. However, the Contractor shall ensure that the entire void can be grouted.

2. Temporary Casing Not Installed

a. Grout material shall be placed by a positive displacement method such as pumping or forced injection by air pressure after water or other drilling fluid has been circulated in the annular space sufficient to clear obstructions. Grout shall be injected in the annular space between the inner casing and either the outer casing or the borehole. The annular space must be a minimum of 1-1/2" for sand-and-cement grout, and not less than three times the size of the largest coarse aggregate used for concrete grout. The grout pipe shall extend from the surface to the bottom of the zone to be grouted.

b. The grout pipe shall have a minimum I.D. of 1" for sand-cement grout and 1-1/2" for concrete grout. Grout shall be placed in one continuous operation from bottom to top. The grout pipe may be slowly raised as the grout is placed but the discharge end of the grout pipe must be submerged in grout at all times until grouting is completed. The grout pipe shall be full, to the surface, at all times until the completion of the grouting. In the event of interruption in the grouting operations, the bottom of the pipe should be raised above the grout level and should not be resubmerged until all air and water have been displaced and the pipe flushed clean with clear water. During placement of the grout the permanent casing shall be vibrated or turned to assist grout settlement.

C. Curing:

1. No drilling or other work shall be permitted in the drill hole within 48 hours after placing grout when Type I Portland Cement is used; or, within 36 hours after placing grout when Type III Portland Cement is used.

3.4 WELL DEVELOPMENT

A. The method of well development shall be Mechanical Surging, unless otherwise approved by the CO. The method, however, shall be consistent with National Ground Water Association’s “Manual of Water Well Construction Practices”.

B. Clean water may be circulated to remove sediment from the well. The method of circulation shall be the Contractor's discretion provided the method agitates the formation to prevent bridging of the sand particles and is capable of removing the finer material. The use of chemicals to aid in development must be approved by the CO.

C. Well development shall continue until, in the opinion of the CO, the sand content can no longer be reduced and well yield cannot be increased by continued development.

3.5 PERFORMANCE TEST

A. The Contractor shall furnish, install and remove the necessary instruments and pumping equipment for each performance test.

B. The test pump shall be capable of pumping variable rates of flow between 5 GPM and 10 GPM from a point 10 feet above the bottom of the well to the surface. The pump must be capable of running uninterrupted the entire length of the test.

C. The method for measuring the water level in the well shall be accurate to within 0.1 foot.

D. The Contractor shall supply a device capable of measuring the flow of water to within an accuracy of ten percent (10%).

E. The initial pumping rate shall be approximately 5 GPM or as otherwise approved by the CO. Pumping rates for subsequent tests shall be determined by the CO based upon the well characteristics observed during the first test and the discharge-head characteristics of the test pump.

F. The goal of the performance tests is to (1) determine the draw-down/recovery characteristics of the well for different pumping rates; and (2) determine the sustained yield of the well if possible with the range of pumping rates selected.

G. The static water level shall be measured before starting each test.

H. For each performance test, the recorded test pumping rate shall be the average of all individual rate measurements taken while the pump is running. Individual rates shall be measured every 10 minutes for the first hour and every 30 minutes thereafter.

I. Draw-down shall be measured according to the following schedule: 0-10 minutes – every minute, 10-45 minutes – every 5 minutes, 45-90 minutes – every 15 minutes, 90-180 minutes – every 30 minutes. At the end of 180 minutes, or when the pumping water level stabilizes, whichever occurs first, the pump shall be turned off. The pumping water level shall be considered “stable” after three consecutive water level measurements, spaced at least 20 minutes apart, show no further measurable drop in the pumping water level.

J. Recovery of the pumping water level shall be measured after each test according to the same time schedule listed above for draw-down measurement. Measurement shall continue for 180 minutes or until recovery is complete, whichever occurs first. Recovery shall be considered “complete” after original static water level is reached or after three consecutive water level measurements, spaced at least 20 minutes apart, show no further measurable rise of water within the casing. If recovery is not complete within 180 minutes, subsequent tests shall be delayed; or static water level adjusted, as approved by the CO.

K. Should the measurement not be made exactly at the time specified, the actual time of each measurement shall be recorded.

L. Discharge water shall be conducted from the pump, to a location approved by the CO, through approved piping or lined ditches to prevent re-circulation of discharged water into the aquifer being tested and prevent surface erosion. The distance of such piping or ditches, from the well, shall not be less than 10 feet or more than 50 feet.

3.6 WELL DISINFECTION

A. Disinfection shall comply with National Ground Water Association’s “Manual of Water Well Construction Practices” using the EPA requirement for minimum concentration of 100 ppm available chlorine.

B. The quantity of chlorine compounds used for disinfection shall be sufficient to produce a minimum of 100 ppm (parts per million) available chlorine in solution when mixed with the total volume of water in the well. A 100 ppm solution should result from utilizing quantities of chlorine compounds, proportion to the depth of water, as listed in the table below:

TABLE 2.3 CHLORINE COMPOUND REQUIRED TO DOSE 100 FEET OF WATER-FILLED WELL AT 100 PPM

Perchloron, ect (Dry Weight)* Per 100 Feet Chlorine Compounds 25% Chloride of Lime (Dry Weight)* Per 100 Feet 5.25% Purex Chlorox (Liquid) Per 100 Feet

Note: Liquid sodium hypochlorite in a 12 percent solution is often sold for water and wastewater treatment plant use, as commercial bleach, or for use with swimming pools. Utilizing a solution of this nature would call for a liquid measure equal to one-half the volumes presented in Column 5.

* - Where a dry chemical is used, it should be mixed with water to form a chlorine solution prior to placing it into the well. This applies to all wells except flowing artesian wells.

3.7 WATER SAMPLES AND TESTS

A. After the well has been developed, tested for performance, disinfected and pumped to remove all traces of disinfectant, the Contractor shall take water samples in accordance with EPA’s Drinking Water Standards for the following:

1. Total Coliforms

2. Nitrates and Nitrites

3. pH

4. Temperature

5. Total Alkalinity

6. Fluoride

7. Conductivity

8. Total dissolved solids

9. Calcium Ca+2

10. Resultant Langlier Index for Corrosion

C. The contractor shall perform a Microscopic Particulate Analysis (MPA) in accordance with the EPA Consensus Method (EPA 910-9-92-029, October 1992). A minimum of 1,000 gallons shall be pumped through the recommended filter size at 1 GPM to obtain the sample.

D. The Contractor shall furnish specially prepared sample containers from a testing laboratory certified by the Colorado Department of Health. The Contractor shall take, or cause to be taken, the required number and type of samples. The Contractor shall prepare and transport all samples to the certified testing laboratory. A list of certified testing laboratories is available from the Colorado Department of Health, Water Quality Control Division, Drinking Water section, 4210 E. 11th Avenue, Denver, Colorado 80220. The Contractor should anticipate a two to three week period for sample analysis. The Contractor shall submit test results to the CO. If the test indicates the ground water does not meet Colorado Primary Drinking Water Regulations for water quality, the Government may opt to seal or abandon the well.

3.8 WELL ABANDONMENT

A. Well abandonment, if directed by the CO, shall comply with State Standards.

3.9 RECORDS

A. After completion of all work required by this section, the Contractor shall submit the following standard forms and information to the CO. The Contractor shall be responsible for forwarding the required forms to the State Engineers Office.

1. Well Construction and Test Report: Form No. GWS-31 (10/94) or current revision;

2. Supplemental Test Report: Form No. GWS-39 (11/90) or current revision;

3. Well Abandonment Report: Form No. GWS-9 (3/03) or current revision, if applicable; and

4. Water Samples and Tests: Copies of all bacteriological, physical, chemical analysis, and MPA test results for the items specified in this section.

B. The standard forms referenced are available from the Colorado Division of Water Resources, Division 5, Department of Natural Resources, P.O. Box 396, Glenwood Springs, CO 81602, (970) 945 5665.

C. More than one Supplemental Test Report form may be required to accurately record the draw-down/recovery data for the three pumping rates required in this section.