03 02674 CONTINENTAL WATER WELLS.docx

DIVISION 2 SECTION WY-02674

SITEWORK WELL DRILLING AND CASING

Rev. 06-90

PART 1: GENERAL

1.01 SUMMARY:

A. Section Includes: Drilling, casing, testing, developing, record keeping, abandonment of water well, disinfection, and installing Contractor-furnished property.

1.02 RELATED WORK:

A. Specifications Sections:

General Information and Requirements Section 01009

1.03 REFERENCES:

A. American Association of State Highway and Transportation Officials

AASHTO T 26 Test for Quality of Water to be Used in Concrete

B. American Society for Testing and Materials:

C. American Concrete Institute

1.04 SUBMITTALS:

A. Certification: Furnish written certification from the manufacturer certifying that the Contractorfurnished property conforms to the requirements of this section. Submittals shall be in accordance with Section 01009General Information and Requirements.

B. Records: Final well logs; drilling samples and or description; written documentation of final yield test and well completion report shall be furnished to the Contracting Officer in the format agreed upon at the Pre-Work Conference upon completion of the well.

1.05 PROJECT CONDITIONS:

A. Well Depths and Material Quantities: Well depths and material quantities listed in the Work Data Sheet are estimates. The final determination of depths and material quantities will be made in the field by the Contracting Officer and will depend on actual geological conditions encountered during the drilling operations. The Contracting Officer will have the option of ordering abandonment of a well at any point during the drilling operation. Well abandonment shall be in accordance with these specifications.

B. Rig and Standby Time: No rig or standby time will be paid for in this Contract.

1.06 SCHEDULING:

A. Drilling Program: At the Pre-work Conference, the Contractor shall submit to the Contracting Officer for approval a complete and practicable drilling program. The program shall provide for orderly performance of the work and be in such form and detail as to show the following:

1. The days of the week and month that work is to be performed.

2.

2. The number and length of each shift per day. The length of a shift may be extended in the field as required to avoid interrupting a drilling and testing operation.

3. Type of rig and support equipment.

4. Plan for disposal of waste.

5. Sequence of drilling operations.

6. Mud (and/or air) program (list of additives, mixing rate) if applicable.

7. Materials list and specifications (casing, slotted casing, well screen, gravel pack, grout, disinfectant, and any other materials incorporated into the project.

8. Drilling water source.

PART 2: PRODUCTS

2.01 GOVERNMENT FURNISHED MATERIALS

A. See Section 01019, Government-Furnished Property if applicable.

2.02 CONTRACTOR-FURNISHED MATERIALS

A. Casing: Materials specified shall be new and free from defects. However, if the contractor deems it necessary or desirable to use temporary casing, the casing may be used, subject to the approval of the Contracting Officer.

B. PVC Well Casing (including any slotted casing): Polyvinyl Chloride (PVC) well casing shall conform as referenced in Section 1.03 B and shall carry the National Sanitation Foundation (NSF) seal of approval for well casing (NSF-WC). Each section of PVC plastic casing shall be marked to show, at a minimum, the diameter, type of material, standard number, SDR number or Schedule, and United States manufacturer. Casing shall be Certa-Lok brand name, or approved equal. Physical dimension shall be described in the Contractor’s submittal based on the SDR number or Schedule required for the well bore conditions defined by the Contracting Officer. Casing (including slotted casing) shall be of the size shown on the Work Data Sheet.

C. PVC Casing Couplings and Fittings: Casing coupling shall be of the same material as casing, and with a pressure rating equal to or greater that casing, and shall be Certa-Lok Coupling brand name, or approved equal. The coupling shall be watertight with locking groves, PVC spline, and gaskets manufactured for the Certa-Lok Coupling. Solvent-weld type fittings shall be designed to be interference free for at least one-half of the socket depth and have a beveled entrance to prevent wiping off of solvents while being installed.

D. PVC Solvent: Primer and cement shall be recommended and approved by the pipe manufacturer. Primer and cement shall be approved by NSF for drinking water.

E. Steel Casing Joints: Shall be watertight, and may be either welded or threaded and coupled.

F. Steel Casing: Well casing shall be API Limited Service grade (or better – i.e. J-55), 15.5 pounds/foot, threaded & coupled. Materials specified shall be new and free from defects. However, if the contractor deems it necessary or desirable to use temporary casing, the casing may be used, subject to the approval of the Contracting Officer.

G. Bentonite: Granular bentonite shall be American Colloid KWK, CS/55 or approved equal. Pellet bentonite shall be American Colloid VolClay or approved equal.

H. Stainless Steel Well Screen (if required): The well screens shall be of the size shown on the Work Data Sheet. The screens shall be of wire-wound, cage-type, V-slot, all-welded construction, type 304 stainless steel. The column, tensile and collapse strengths shall be certified for depth and casing of individual wells. At least 95% of the screen slot opening shall be completely clean and free of burrs, frayed edges, cuttings, slag and other such materials.

I. Drilling Fluid Additive: An NSF drinking water approved sodium or ammonium base, biodegradable foaming agent ("High Foam" or an approved equal) will be allowed for airrotary drilling. Other additives (i.e. Drispac Plus, Alcomer 123L, etc.) must be submitted with the drilling plan and approved by the Contracting Officer.

J. Gravel Packing: The gravelpack material shall be clean, with wellrounded grains that are smooth and uniform. The material shall consist of a minimum of 95% siliceous particles, with a maximum of 5% calcareous material. The gravel pack will be of appropriate size for the slot size in the screen or slotted casings installed in the well and as approved by the Contracting Officer.

K. Formation Stabilizer: Formation stabilizer may be pelletized bentonite, or bentonite gravel material free of dirt and foreign matter, hydrated per manufacturer’s specification or bentonite grout (i.e. Black Hills Ultra Grout or equivalent) mixed to a specific gravity of 9.75 to 9.85 pounds per gallon with a solids content of 22% to 25%.

L. Cement Grout Mix: Neat Cement Grout shall consist of a mixture of Type II Portland cement and not more than 6 gallons of clean water per bag (94 pound bag or one cubic foot). Sand Cement Grout must consist of a mixture of Type II Portland cement, sand, water and a maximum of 2% calcium chloride in a proportion of not more than 6 gallons of water per sack of cement (94 pound sack or one cubic foot) and not more than one part sand to one part cement.

M. Water used for drilling and cementing operations shall be potable water or from a source approved by the Contracting Officer.

N. Casing Centralizers: Shall be stainless steel sized to fit the casing and the hole placed on the bottom, top, and through the screened interval and spaced not more than 20 feet apart.

2.02 EQUIPMENT:

A. Drilling Equipment: Except otherwise specified, the type of drilling equipment shall be determined by the driller.

B. Minimum Equipment: The Contractor shall furnish equipment of sufficient size and in sufficient quantities to drill 1-1/2 times the estimated drilling depth of the deepest well listed in the Work Data Sheet.

C. Air Volume Requirement: (Air-Rotary Drilling): Contractors intending to use air-rotary drilling equipment should be aware of the volume of air required to maintain proper up-hole velocity to lift the drill cuttings from the bore hole under various conditions. The volume of air produced by an on-rig compressor, or in conjunction with auxiliary compressors shall be sufficient to lift drill cuttings to the ground surface for the size and estimated depth (1-1/2 times the estimated depth) of the bore holes shown on the Work Data Sheet.

D. Well Development: Well development methodology (jetting, surging, surge block, swabbing, etc.) shall be approved by the contracting officer. Contractor shall be cognizant of the collapse strength of the casing and hydraulic conditions of the well in order to perform well development in a manner as to not compromise the casing and well.

E. Well Testing (pumping method): Furnish and install a test pump of sufficient capacity to test the well at 1-1/2 times the rate of flow stated in the Work Data Sheet. Devices for measuring the flow of water, such as a calibrated weir box, an orifice, or a water meter shall be provided by the Contractor. Provide an e-tape (well probe) or an airline with a gauge, hand pump (or other means of pressuring the line), and check valve for measuring the water level in the well.

F. Well Testing (bailing Method): Furnish bailing equipment sufficient to achieve a yield test at a rate equal to or greater than 1-1/2 times that specified in the Work Data Sheet, and to continue for at least one hour after the water level has become stable. The bailing device shall be a commercial type with a fixed volume. Contractor shall be cognizant of the collapse strength of the casing and hydraulic conditions of the well in order to perform well development in a manner as to not compromise the casing and well.

G. Well Testing (air-lift Method): Furnish airlifting equipment sufficient to achieve a rate of flow equal to or greater than 1 1/2 times that specified in the Work Data Sheet, and to maintain this rate for at least one hour. Size and depth of well bore, drill pipe size, and compressor capacity must all be considered. Contractor shall be cognizant of the collapse strength of the casing and hydraulic conditions of the well in order to perform well development in a manner as to not compromise the casing and well.

2.03 CEMENT FOR PLUGS AND CASING SEAL:

A. Cement: The cement slurry shall be API Class G, slurry weight 15.8 lbs. per gallon (118 lbs. per cu. Ft.) mixed with not more than 5 gallons of water per 94 pound sack. The cement shall be in bulk with any additives blended at the bulk-cement facility. Additives may include 2% Calcium Chloride materials to help prevent circulation loss or additives determined necessary after the hole is drilled. All additives must be approved by the contracting officer prior to use. The mixing water shall be potable.

PART 3: EXECUTION

3.01 PREPARATION:

A. Clearing: Worksite clearing shall be limited to an area 50 by 50 feet. Any additional disturbance must be approved by the contracting officer.

B. Site Preparation: Surface disturbance at the site shall be minimized. However, the construction site may be leveled as necessary for drilling operations. Resultant cut or fill slopes shall not be steeper than 4:1, unless approved by the contracting officer.

3.02 INSTALLATION:

A. Drilling Location: Drill the well at the location staked or otherwise designated by the Contracting Officer.

B. Hole Size: The hole shall be of sufficient diameter to provide a minimum 2” annulus. In example, not less than 9-1/2 inch for 5-inch nominal size casing and large enough to accommodate tremie pipe.

C. Estimated Drilling Depth: As shown on Work Data Sheet.

D. Using Pilot Hole as Test Well: If the Contractor drills a pilot hole and encounters water, the Contracting Officer, after considering all the evidence, shall determine whether to deepen the hole, enlarge the hole to the size specified, or to abandon the well. The pilot hole shall be a minimum of 5 inches in diameter.

E. Water Used to Facilitate Completion of Well: Any water introduced into a well by the Contractor to facilitate drilling, developing, cleaning and gravel packing operations, including water added to an approved drilling additive shall be potable water or from a supply approved by the Contracting Officer.

F. Drilling Fluid Additives: All drilling fluid additives must be NSF approved for drinking water.

G. Recirculation and Mud Drilling: Bentonite based mud drilling is discouraged. If bentonite based muds are proposed under special drilling circumstances, justification must be provided to the Contracting Officer. All drilling programs (polymer based muds, bentonite based muds, air foam, etc.) must be approved by the Contracting Officer.

H. Depth of Casing: The hole shall be cased the full depth unless casing of a portion of the well is deemed unnecessary by the Contracting Officer.

I. Backfill: If in the process of locating waterbearing strata, the well was drilled deeper than needed, the Contractor shall back fill the well with approved formation stabilizer to a point 20 feet below the bottom of the lowest waterbearing strata. Back fill shall be disinfected in the same manner as the gravel pack.

J. Casing Installation: Casing shall be installed in accordance with the drilling method used. For PVC casing, the joined casing string shall be installed in a predrilled hole. Casing shall not be dropped onto the bottom of the well hole, nor forced down against the bottom of the hole during installation. Casing shall be kept continually suspended during and after installation, until such time that all of the gravel pack and formation stabilizer material have been properly installed.

1. Casing joints shall be watertight.

2. A 5 to 20 foot of casing (blank or slotted, as determined by the contracting officer), sealed and pointed or capped at the lower end, will be installed below the screen (rat hole).

K. WaterBearing Strata: If it is necessary to extend casing through developable waterbearing zones, the portion of the casing opposite the water bearing zones shall be screened or sealed off as determined in the field by the Contracting Officer.

1. Casing centralizers shall be installed on the casing immediately above and below the screened zone, and every 20 feet through the screened zone.

L. Surface Seal: Installation of the seal shall be performed in the presence of the Contracting Officer. No work shall be done on the well until surface grout has set at least 24 hours after final placement.

M. Stainless Steel Well Screen: The Contractor shall select the installation method, in accordance with the screen manufacturer's recommendations. Screens may have either a welding ring, pipe-thread, or spline lock end fittings. Welds shall be made with stainless-steel welding rod. The screen fittings shall be stainless steel of the same type as the screen. Joints must be straight and tight, and retain 100% of the original screen strength.

N. Gravel Packing: Install approximately a 2 inch thickness (minimum) of gravel pack material in the annular space in the zones opposite the screens including 5 to 20 feet below (rat hole) and five feet above and below each screened zone or as determined by the Contracting Officer upon review of the logs. Placement of gravel pack, formation stabilizer, and grout shall be performed in the presence of the Contracting Officer.

1. Disinfection: Disinfect the gravel pack material by mixing 1 pound of calcium hypochlorite (65% available chlorine) in each cubic yard of packing material as it is installed in the well.

O. Water Bearing Formation Seal: Install bentonite gravel or pellet material for a thickness of ten feet directly above the gravel pack. This material shall be disinfected and installed in the same manner as the gravel packing. Installation of the seal shall be performed in the presence of the Contracting Officer.

P. Zone Isolation Seal: If water yielding zones are encountered that are of unacceptable quality water, these zones will be sealed off with bentonite. Install bentonite grout, gravel or pellet material for a thickness of at least ten feet directly above and below the zone to be isolated.

Q. Formation Stabilizer: Install formation stabilizer material in the remaining zones in the well which do not require gravel pack material or surface grout. Installation of the formation stabilizer shall be performed in the presence of the Contracting Officer.

3.03 FIELD QUALITY CONTROL:

A. Alignment:

1. As per the State of Wyoming Water Well Minimum Construction Standards, the well shall drift off plumb no more than one degree per 100 feet of borehole. The alignment shall allow a 40-foot long section of pipe, ½ inch less than the inside diameter of the casing, to pass freely from the top of the casing through the anticipated pump setting depth.

2. If the well does not pass the alignment test, correct the alignment or abandon the well and drill a new well within 50 feet of the original hole, at no additional cost to the Government. The Contractor shall abandon in accordance with state law, prior to starting a new hole.

3.04 WELL DEVELOPMENT:

A. General: After a well has been completely constructed and all drilling fluids and additives removed from the well, each exposed water-bearing zone targeted for water production shall be developed. Development work shall be performed in the presence of the Contracting Officer.

B. The driller shall develop the well until the produced water does not contain appreciable amounts of sand, silt, or turbidity.

3.05 PROTECTION:

A. Drilling Waste: Drilling waste such as drilling fluid and drill cuttings shall be removed so that wastes will not interfere with installation of the well platform and pumping equipment and will not pollute surface waters or cause contamination of the well. Drill cuttings shall be scattered so that the material is 1-inch or less in depth or as approved by the contracting officer.

3.06 WELL LOG AND SAMPLES:

A. Well Log: The Contractor will record drilling and logging information in the format and/or on the forms agreed to at the pre-work conference. The Contractor maintained well log shall meet the state requirements and include entries for the formation and each apparent change in material penetrated, or every 10 feet, whichever is lesser. The log of the well shall show material penetrated and full descriptive notes made of each stratum found by the drill and difficulties or any usual conditions met in drilling. Water-bearing strata shall be described in detail as to loose or compact material, color, and if gravel, whether it is water-worn or angular. The presence of clay shall be noted. The log must be kept up-to-date with the progress of the well drilling, and shall be available for inspection by the Contracting Officer during drilling operations and after completion of drilling.

B. Logging: The Contractor shall collect samples of well-cuttings at ten-foot intervals and, as per the Contracting Officers instructions, place them in an orderly fashion on the ground near the drill site where they can be reviewed throughout the drilling process or placed in sample bags. The sample bags shall be marked showing the depth at which the samples were collected and the date and time that the samples were collected.

1. For cable tool drilling operations, take a sample at the end of each drilling run.

2. For air-rotary and other types of drilling operations, take a cutting sample at least every 10 feet and at formation changes.

C. Additional Requirements: The Contractor will complete a report on the completion of the well to include information supplementary to the well log. This can be submitted on a form 7240-1, Record of Wells (as supplied by the Contracting Officer), or in a format approved at the pre-work conference. The Contractor shall submit this report to the Contracting Officer.

D. Information for State filing: The Contractor shall furnish the Contracting Officer with a copy of the drilling information required by State law for filing on water wells.

3.07 PRELIMINARY YIELD TESTING OF THE WELL:

A. General: The Contractor shall make a preliminary yield tests or estimates during drilling operations on each water-bearing stratum penetrated as requested by the Contracting Officer and only if the test will not compromise the bore-hole integrity.

B. After the well has been completely constructed and cleaned, the Contractor shall make a final preliminary yield test during the development of the well. He test may be conducted by air lift, bailer, or submersible pump. The Contracting Officer shall have the option of rejecting the air lift method on low yielding wells. If the Contracting Officer rejects the air lift method for determining yield, the Contractor will then be allowed to determine the approximate yield of the zone by calculating the gallons of water coming into the bore hole over a 20-minute period of time.

3.08 ABANDONMENT OF THE WELL:

A. Abandonment Due to Contractor’s Actions: When the drilled well must be abandoned because of actions of the Contractor, including but not limited to lost tools, damaged well, misalignment, inability to properly install casing string and/or gravel pack, or other causes attributed to carelessness or poor workmanship, the Contractor shall pull casing (if installed) that can be removed and fill the hole with grout, cement or concrete grout, or bentonite in accordance with State regulations and requirements. The Contractor shall be responsible for drilling a new well within 50 feet of the original well.

B. Abandonment Due to Other Causes: When the well must be abandoned because of inadequate quantity or quality of the water, or for another reason not the fault of the Contractor, the Contractor shall pull the casing (if installed) that can be removed, and shall fill the hole with any of the materials described above in accordance with State regulations and requirements. The order to abandon the well must be in writing from the Contracting Officer.

3.09 SANITARY PROTECTION OF WELLS:

A. General: The Contractor shall protect the well during the construction and testing period to prevent tampering or seepage of contaminated water, petroleum products, or other contaminates into the well from the ground surface.

B. Seal: When the well is completed, install a cap or sanitary well seal designed to prevent pollutants from entering the well. Seal or screen off equipment openings that permit direct access to the well to prevent entrance of foreign matter or contaminates.

C. Grading: Slope the surface immediately surrounding the top of the well casing wellhead away from the well in all directions.

D. Correcting Contamination: If the well becomes contaminated, or water with undesirable physical or chemical characteristics enter the well due to the neglect of the Contractor, corrective work including the supplying of casing, seals, sterilizing agents, or other materials as may be necessary to prevent contamination of the aquifers shall be performed at the Contractor's expense.

3.10 DISINFECTION

A. General: All disinfection shall be done in the presence of the Contracting Officer. Disinfection (both following drilling and following pump installation) shall be done in compliance with the State of Wyoming Water Well Minimum Construction Standards.

PART 4: MEASUREMENT AND PAYMENT

4.01 METHOD OF MEASUREMENT:

A. General:

1. Rig or Standby time will not be paid for.

2. No payment will be made for drilling, installing casing, removing casing, or the plugging of a well abandoned due to Contractor's actions.

3. No payment will be made for time spent developing and testing wells which occur prior to the well being completed (cased, gravel packed and grouted).

4. When the Contracting Officer determines that a well should be drilled deeper, the Contractor shall be required to drill a maximum of one and onehalf times the estimated depth shown on the Work Data Sheet at the unit price bid. The Contractor shall be required to provide all additional work and materials needed to satisfactorily complete the deeper well, at the unit price bid for the respective work performed.

5. No payment will be made for disinfection of the well, furnishing and installing the cap or compression seal, and casing centralizers. The Contractor shall include consideration for these items in the bid price for other items of the Contract.

B. Units:

1. Well drilling, installing casing and well screen, gravel pack material, formation stabilizer/bentonite seal, and grouting will be measured and paid for per linear foot.

2. Payment will be made per linear foot for drilling, installing casing and well screen, gravel pack material, formation stabilizer/bentonite seal, and grouting for the quantity abandoned due to causes not the fault of the Contractor.

3. Payment for pulling casing and filling the hole when the well is abandoned due to causes not the fault of the Contractor will be based on the price negotiated by the Contracting Officer.

4. Well development and testing will be measured and paid for by the number of hours of development and testing required for each well beginning when the pumps, compressors, and other equipment have been installed and actual development and testing have begun.

5. If the Contracting Officer determines from information obtained from a Contractor's pilot hole that the well site should be abandoned due to no fault of the Contractor, measurement and payment will be negotiated and the Contract will be modified in writing.

6. Concrete well platforms, if required, will be measured and paid for, on a per-each basis, after installation and acceptance.

7. Wireline logging, if required, will be paid for on a per-each basis.

8. Mobilization to the job site and between locations will be measured and paid for as a lump sum.

4.02 BASIS OF PAYMENT:

A. Payment: Prices and payment will be full compensation for the work described in this section. Payment will be made under:

Pay Item Pay Unit

WY-02674 (4) Furnish and install 5-Inch Slotted Casing ..........Linear Foot

END OF SECTION

WY-02674 - 1

HIGH DESERT DISTRICT CONTINENTAL PEAK WATER WELLS