PRODUCTION WELL CONSTRUCTION SPECIFICATIONS. (3) The construction and development of one 450-feet deep Class I water production well

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1 PRODUCTION WELL CONSTRUCTION SPECIFICATIONS PART 1 - GENERAL 1.1 DESCRIPTION A. Work included covers the following: (1) Pilot hole drilling (2) Furnishing materials (3) The construction and development of one 450-feet deep Class I water production well (4) 24-hour yield & drawdown testing, and collection of VDH-required water quality samples 1. Provide one 6-inch nominal I.D. production well that will produce a minimum yield of 50 GPM (gallons per minute). The estimated total depth of the well is 450 feet. The CONTRACTOR shall guarantee that the completed well shall have a 24-hour well efficiency of at least 75%. The 24- hour well efficiency shall be determined by dividing the actual specific capacity achieved after pumping 24-hours at a pre-selected constant capacity by the theoretical specific capacity obtainable from the aquifer as determined by a residual drawdown semi-log plot of the well test data. The residual drawdown plot is a plot of the measured water level after pumping the well at a constant capacity has ceased vs. the logarithm of the ratio of the time since the pump started (t), to the time since the pump stopped (t'). Data must be taken at frequent intervals (same as the pump test) for 24-hours after the 24-hours constant capacity pump test is complete. The transmissivity is determined from the slope of residual drawdown plot and calculated by the formula: T = 264Q/S Where: Q = Constant Pumping Rate in GPM S = Slope of Plot in Ft./Log Cycle T = Gallons per Day per Foot The theoretical 24-hour specific capacity of GPM per foot of drawdown is defined as the transmissivity in gallons per day per foot determined from the residual drawdown plot divided by

2 The CONTRACTOR shall report all test data, calculate the transmissivity (T) of the aquifer and well efficiency, and turn over copies of all original work papers to the OWNER for review prior to demobilization from the site. Should the 24 hour well efficiency be less than 75% and the well produce less than the minimum required yield, the CONTRACTOR shall be required to continue development of the well and retest the well upon completion. No additional payment shall be made for additional development or retesting. Should the CONTRACTOR not be able to obtain the required 75% efficiency and the well produce less than the minimum required yield, the OWNER may do either of the following: (1) Reject the work and require the CONTRACTOR to vacate the site, in which case the OWNER shall not owe any monies for the work done in the production well phase. Previously paid monies for the production well phase shall be refunded by the CONTRACTOR to the OWNER. The CONTRACTOR may salvage material and must seal the well per Virginia Department of Health requirements. (2) Allow the CONTRACTOR to permanently abandon the failed well and drill a new production well at a location to be determined by the OWNER at no additional cost to the OWNER. B. The wells will be located as shown on the site plan. The OWNER will provide a stake at the desired well location. The cost of any clearing or grading of the sites necessary for ingress or egress of equipment shall be included in the bid prices bid for a well. Should additional wells be required the OWNER reserves the right to choose their location. 1.2 REFERENCES A. Standards referenced in this Section are listed below: 1. American Society for Testing and Materials, (ASTM). a. ASTM A 53, Specification for Pipe, Steel, Black and Hot-Dipped, Zinc- Coated, Welded and Seamless. b. ASTM A 139, Specification for Electric-Fusion (ARC) - Welded Steel Pipe (NPS 4 and Over). c. ASTM C 150, Specification for Portland Cement. d. ASTM C 494, Specification for Chemical Admixtures for Concrete. e. ASTM C 618, Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Portland Cement Concrete. f. ASTM D 1784, Standard Specifications for Rigid PVC Compound and Chlorinated PVC Compounds. g. ASTM D 2037 h. ASTM F 480, Standard Specification for Thermoplastic Well Casing Pipe and Couplings made in Standard Dimension Rations, SCH 40 and SCH 80. 2

3 2. American Welding Society, (AWS). 3. American Water Works Association, (AWWA). a. AWWA Standard for Water Wells. 4. U.S. Environmental Protection Agency, (EPA). a. Manual of Water Well Construction Practices EPA Document #EPA-570/ Virginia Department of Health a. Waterworks Regulations 12 VAC5-590 (2014) 1.3 QUALITY ASSURANCE A. Records: 1. The records and logs, as described in Article 1.4 below, will be reviewed to assure the quality of the pilot hole and production well construction prior to acceptance of the Work by the ENGINEER. B. The OWNER will perform construction observation of the pilot hole drilling and testing programs, and the abandonment of the pilot hole, if necessary, and the drilling and testing of the water production well. CONTRACTOR shall cooperate with the OWNER in performing this observation, which shall include, but not be limited to, observing construction operations and reviewing cuttings and records of the drilling and testing. C. All welding performed shall be of high quality and in accordance with American Welding Society Standards. D. CONTRACTOR shall perform a test for plumbness and alignment of the water production well casings in accordance with AWWA A-100, prior to acceptance of the well by the ENGINEER. E. Products used in the Work specified under this Section shall be produced by manufacturers regularly engaged in the production of such items who have a successful history of product acceptability, as interpreted by the ENGINEER. Equipment of less quality or of inferior design to that specified will not be accepted. 1.4 SUBMITTALS A. Shop Drawings: 1. Shop Drawings shall be submitted by CONTRACTOR to the ENGINEER for approval prior to starting drilling operations for the water production well. The submittal shall include, but not be limited to, the following items: a. Surface casing. b. SDR 17 Certa-Lok PVC Well casing. c. 304 Stainless Steel well screen & pipe. d. SDR17 Certa-Lok PVC reducing coupler. e. Cement grout mix design. f. Gravel pack material samples including sieve analyses specifications. g. Geologic sample catcher or equivalent. 3

4 h. cfm rating for air compressor. i. Complete equipment list. The list shall include, at a minimum, the following information: 1) Rotary Rig: a) Rated Safe loading for mast, substructure and draw-works. b) Mast height. c) Available rotary table horsepower. d) Available mud pump horsepower. e) Circulating rate. f) Total available rig horsepower. 2) Drill Equipment: a) Type or types of bits. b) Diameter, total length and number of drill collars, including total weight. c) Size of drill pipe. d) Rotary speeds. j. Well drilling and development methods. 1) CONTRACTOR shall submit to ENGINEER for review installation plan for PVC Cased Well addressing the following issues: a) Grout thickness and type. b) Grout installation technique (lifts, etc.) c) Well development technique and timing. d) Methods to minimize heat of hydration. (fluid circulation inside casing, etc.). e) Well disinfection procedure k. Pumps and motors, including all down hole and surface development equipment. l. Proposed methods for disposal of waste water, drilling fluid and drill cuttings. B. CONTRACTOR shall perform or have performed the following geophysical logs on the pilot hole: 1. Spontaneous Potential and Resistivity Log (Electric Log). 2. Gamma-Neutron Log. 3. Temperature Log. 4. The interval to be logged shall be the total depth of the pilot hole, subject to satisfactory pilot hole conditions, the limitations of the logging technique or other directives from the ENGINEER. CONTRACTOR shall cooperate with the company or companies running such surveys and shall have at least two employees available to help in rigging the survey equipment. 5. All geophysical log interpretation shall be done by a qualified log analyst. The log analyst must be a Professional Geologist or Professional ENGINEER able to demonstrate competence through background, training and experience when so called upon. It is the CONTRACTOR'S responsibility to assure that all log analyses and/or interpretations are made by a person so qualified. 4

5 6. Upon completion of the pilot hole to the specified depth, the CONTRACTOR shall provide the necessary equipment to run an electric log of the hole. The log shall be a recording of the resistivity and spontaneous potential of the formations and will be obtained through the use of single point, short normal, and long normal methods. Resistivity readings shall be 64-inch normal ohm M²/M, 16 /64 normal ohm M²/M, 48-inch lateral single point ohms/in fluid resistivity, and self-potential MV/in. Logging equipment shall be capable of recording readings on a vertical scale of 20-feet per inch. A natural gamma log shall also be run using the same vertical scale as the electric log. C. A Daily Driller's Report shall be kept available at the Site for review by the ENGINEER and at the conclusion of water production well drilling for the well, two neat, legible copies of this report shall be submitted to the ENGINEER. This log shall contain, but not be limited to, the following information for each day's activity: 1. Number of crew on the Site and name of superintendent for each shift. 2. Description of all formations encountered. 3. Number of feet drilled. 4. Number of hours on the job. 5. Number of hours of drilling operations. 6. Number of hours of shutdown. 7. Drilling fluid viscosity (every four hours of drilling operations). 8. Rate and volume of make-up water used for each formation. 9. Water level at each change or formation, if readily measurable. 10. Emergency phone numbers of personnel involved in well construction. D. The Penetration Rate Log shall be kept available at the Site for review by the ENGINEER and at the conclusion of both the pilot hole drilling and water production well drilling, two neat, legible copies of this report shall be submitted to the ENGINEER. This log shall contain, but not be limited to, the following information for each day's activity: 1. Time Log showing the actual penetration time required to drill continuously each foot of hole (Geolograph or engineer approved equivalent). 2. Types of bits used in each portion of the hole (e.g., drag, milltooth roller or button type). 3. Weight on bits during the drilling of the various types of formations in the various sections of the pilot hole. 4. Whether bits were designed for soft, medium, or hard formations. E. A Driller's Log shall be kept available at the Site for review by the ENGINEER and at the conclusion of both the pilot hole drilling and water production well drilling, two neat, legible copies of this report shall be submitted to the ENGINEER. This log shall contain, but not be limited to, the following information for each day's activity: 1. The reference point for all depth measurements. 2. The depth at which the first water is encountered. 3. The depth at which each stratum is encountered. 4. The thickness of each stratum. 5

6 5. The identification of the materials of which each stratum is composed, such as: a. Clay. b. Sand or silt. c. Sand and gravel (indicate properties). d. Cemented formation (indicate rock type). e. Hard rock (indicate rock type). 6. The depth interval from which each formation sample is taken. 7. The depth at which the hole diameters (bit sizes) change. F. Within seven days after completion of drilling, a complete and accurate log of the water production well shall be submitted by CONTRACTOR to the ENGINEER. G. If CONTRACTOR requires any changes to these Specifications, as outlined herein, CONTRACTOR shall submit, in writing, the changes to the ENGINEER 24 hours prior to commencement of the change. Change shall require approval of the ENGINEER prior to their implementation. H. CONTRACTOR shall submit certified test reports to the ENGINEER to indicate compliance of steel casings and screens with the requirements of this Section. I. The detailed information of the water production well shall be submitted to the ENGINEER and shall show: diameter, wall thickness, material type, depths of setting and lengths of casings and screens installed; details of reducing sections; type, aperture size and pattern of openings in screen; borehole diameters; cemented surface casing; gradation of gravel pack, quantity of gravel initially installed, quantity of gravel added during development operations; and all other pertinent details. J. After completion of the water production well construction CONTRACTOR shall submit to the ENGINEER two plots of plumbness and alignment in planes oriented at 90 degrees with respect to each other based or deviation and direction intervals no less than 100-feet. The plumbness test shall be conducted in accordance with AWWA Standard A K. CONTRACTOR shall submit development and test data showing production rate, static water level, pumping level, drawdown, sand production, and other relevant information concerning the method of development and testing of the completed water production well. L. Furnish to ENGINEER and all logs, samples, tests and other data required, including well completion reports. 1.5 SITE CONDITIONS A. The water production well shall be drilled at the location shown on the site plan. 6

7 B. The location of any necessary mud pits or other excavations shall be approved by the OWNER prior to excavation. C. The CONTRACTOR shall be responsible for site access. The CONTRACTOR shall provide any necessary mats or gravel aggregates for site access. The CONTRACTOR shall remove all mats and gravel aggregates upon completion of the well construction and testing. The CONTRACTOR shall be responsible for preventing soil and mud from being deposited on the paved road surface. If the CONTRACTOR deposits mud or soil on the paved road he shall remove it and restore the roadway to the satisfaction of the OWNER. The CONTRACTOR shall not seek any damages of costs for recovering any vehicles associated with the construction and testing of the well. PART 2 - PRODUCTS 2.1 CASING A. Surface casing shall be in new condition. All surface casing shall be constructed of 14- inch I.D. SCH 40 PVC and manufactured in conformance with ASTM F480. Surface casing may be solvent welded. B. Well casings and couplings shall be new. All well casings and couplings shall be constructed of 6.9-inch O.D. SDR 17 PVC and manufactured in conformance with ASTM F480. All well casings and couplings shall be Certa-Lok PVC well casing as manufactured by Certainteed Corporation or approved equal. Solvent weld well casing will not be approved. 2.2 SCREENS & BLANK SECTIONS A. Screen shall be new and constructed of 6.0-inch nominal I.D. (6-inch pipe size) rodbased, V-shaped wire wrapped 304 stainless steel well screens, manufactured by Johnson Screens (or approved equivalent). Screen slot size and minimum area of openings per linear foot shall be identified by the ENGINEER after review of the sieve analyses from pilot hole drilling provided by CONTRACTOR as described in Paragraph 3.1.B.3, below. The ends of each length of screen shall be machine-beveled perpendicular to the screen axis to ensure straightness of each assembled section. Both ends of each screen section shall be furnished with a factory-welded collar 1/4-inch thick and having a minimum width of 1.5-inches. Collars shall be of the same physical and chemical properties as the screen and shall be rolled to fit the screen s outside diameter. The inside edge of the collars shall be ground or sufficiently scarfed to remove sharp edges or burrs. B. Blank sections shall be constructed of slot or tight-wind 304 stainless steel well screen, as described above. 7

8 2.3 CENTRALIZERS A. The casing and screen shall be fitted with approved centering guides or brackets, installed at points as directed by the ENGINEER, but in no case more than at 60-foot intervals. These guides shall be oriented in such a manner as to facilitate the installation and removal of tremie pipes required for grouting operations and sand packing in the annulus. 2.4 FILTER PACK MATERIAL A. The filter pack material shall be at least 95 percent silica in composition, manufactured by U.S. Silica Fil-Pro (or approved equivalent). The filter pack shall have a uniformity coefficient of 2.5 or less. It shall be hard, well-rounded, graded, water-worn material washed clean of silt, dirt, and foreign matter (crushed gravel, angular particles, or other non-specified material will not be accepted). Filter pack material shall be subject to the approval of the ENGINEER. Filter pack specification shall be identified by the ENGINEER after review of the sieve analyses provided by CONTRACTOR as described in Paragraph 3.1.B.3., below. CONTRACTOR shall have certified testing laboratory perform a sieve analysis to verify conformance with the specified gradation and material. Failure to meet the specified gradation or material requirements will result in rejection of the filter pack material provided by CONTRACTOR. The filter pack material, if stockpiled at the well site, shall be kept free of all foreign matter. 2.5 BENTONITE GROUT A. Bentonite grout shall be Baroid IDP E-Z Seal (or approved equivalent) mixed in accordance with manufacturer s recommendations and shall be placed discretely in the borehole annulus using a positive displacement pump and tremie pipe. 2.6 NEAT CEMENT GROUT A. A mixture of Portland Cement (ASTM C 150) and not more than six gallons of clean water per bag (one cubic foot or 94 pounds) of cement, shall be used. The use of special cements, bentonite to reduce shrinkage, or other admixtures (ASTM C 494) to reduce permeability, increase fluidity, and/or control time of set, and the composition of the resultant slurry, shall be approved by the ENGINEER prior to placement. The neat cement grout weight shall be measured prior to installation as an indicator of the cement-water mix ratio. The cement grout slurry shall not exceed 15.6 lb/gal (117 lb/cf). Pozzolanic (fly ash) material as an additive shall not be used. PART 3 - EXECUTION 3.1 PILOT HOLE A. Drilling Method: 1. CONTRACTOR may elect to drill or auger the surface casing borehole and install the casing as described under Paragraph 3.2.A.6., below. CONTRACTOR shall do this at his own risk since the ENGINEER may choose to abandon the pilot hole instead of completing the water production well. 8

9 2. The conventional mud rotary drilling method shall be used by CONTRACTOR for the construction of the pilot hole. 3. The drilling operations shall be conducted between the hours of 7:00 am-7:00 pm, Monday through Saturday, exclusive of County-observed holidays. 4. The pilot hole shall be drilled to a depth of 450 feet. Upon completion of drilling of the pilot hole, geophysical logging will be conducted. 5. The minimum diameter of the pilot hole shall be 5 7/8 -inches, and maximum diameter shall not exceed 9 7/8 -inches. 6. NSF approved sodium bentonite based drilling fluid only shall be used, such as Baroid IDP Quik-Gel or approved equivalent. Appropriate polymers and other additives may be used to enhance the drilling, as recommended by the drilling fluid manufacturer. Should lost circulation or other drilling conditions require the addition of bentonite, lost circulation materials, or other such materials, the addition of these materials shall be made only upon approval of the ENGINEER. All additives should be NSF approved and non-biodegradable. Procedures shall be adapted to ensure the removal of these additives during development. Drilling fluid shall be tested every 4 hours (minimum) for fluid weight, viscosity, ph, sand content, and filter cake thickness, as recommended by the manufacturer. In the event the fluid properties are found to be outside the manufacturer s recommended specifications, action shall be taken to correct the fluid properties, prior to continuation of the drilling. 7. In the event that lost circulation conditions are encountered during the drilling process, immediate remedial action shall be taken by CONTRACTOR to restore circulation of the drilling fluid by conventional techniques. Cementing, shall not be employed. Only materials acceptable in typical water production well drilling shall be used to control loss of circulation. All drilling materials shall be NSF approved and non-biodegradable and shall be approved by the ENGINEER prior to use. 8. The complete drilling of the pilot hole shall be done by CONTRACTOR to fulfill the Contract requirements. B. Geological Sampling During the Drilling Procedure: 1. Samples of drilled material shall be taken at ten foot intervals to the total depth of the pilot hole. The driller shall take steps to ensure the accuracy of depth levels for sample collection. Two common half-pint geologic sample bags with a draw-string top shall be filled with cuttings for each zone sampled. Each bag shall be marked, on a tag firmly attached thereto, using ink, indelible pencil, or other medium that is resistant to moisture and sunlight, with the water production well designation, the date and time, and the drilled interval it represents. CONTRACTOR shall be responsible for the safe storage of formation samples until such times as they are accepted by the ENGINEER. 2. A cutting sample catcher approved by the ENGINEER shall be used to obtain representative formation samples. CONTRACTOR shall ensure geologic samples are representative of the depth through which drilling is proceeding. 3. CONTRACTOR shall submit a minimum of two samples of drill cuttings for each 10 foot interval to be screened, selected by the ENGINEER, to a certified testing laboratory for sieve analysis. Results of the sieve analyses shall be made available to the ENGINEER, prior to reaming the pilot hole. 9

10 C. Well Log: 1. An accurate written log shall be maintained at all times, by CONTRACTOR. CONTRACTOR shall record the type, character, and depth of materials encountered, thickness of strata, water table depth and any additional information that may be helpful in interpreting the drilling log. In addition CONTRACTOR shall maintain a Drilling Penetration Rate Log at all times during drilling operations. The Drilling Penetration Rate Log shall include depth of penetration per time interval and shall also include documentation of periods of inactivity, fluid circulation, and other pertinent details as determined by the ENGINEER. All measurements for depths shall be referenced to existing ground surface at the water production well site. On completion of the borehole, five copies of the driller's formation log and the Drilling Penetration Rate Log shall be furnished to the ENGINEER. D. Geophysical Logging: 1. After reaching total depth of the pilot hole, CONTRACTOR shall continue circulation for sufficient time to remove the cuttings from the hole. If the geophysical logging tools cannot be lowered to the bottom of the pilot hole, CONTRACTOR shall run the drilling tools to the bottom one additional time and circulate the hole clean at his own expense. 2. Geophysical logging will be conducted at the expense of CONTRACTOR. Geophysical logs shall be made available to the OWNER and ENGINEER. 3. The following geophysical logs shall be obtained: a. Spontaneous Potential and Resistivity Log (Electric log). b. Gamma-Neutron Log. c. Temperature Log. E. Evaluation: 1. The ENGINEER will require a 72-hour period, commencing with final receipt of all sieve analyses and geophysical logs in order to complete the evaluation of the findings of the pilot hole. CONTRACTOR shall be responsible during this period for taking all measures necessary to ensure the integrity of the pilot hole and to protect the drilling site. Not later than 72 hours after final receipt of all sieve analyses, geophysical logs, and analytical results, the ENGINEER shall notify CONTRACTOR to undertake reaming of the pilot hole as the first step in construction of a water production well or to abandon the pilot hole in accordance with this Section. F. Abandonment: 1. If required, the borehole shall be abandoned in such a manner to prevent contamination of the aquifers encountered in the hole. The borehole shall be filled completely with neat cement grout, placed from the bottom up via tremie pipe. If temporary casing has been installed, it may be salvaged. Casing left in the ground shall be cut at a minimum depth of 5 feet below grade. 10

11 3.2 PRODUCTION WELL A. Well Construction: 1. The conventional mud rotary drilling method shall be used by CONTRACTOR to ream the pilot hole. 2. The hole shall be initially reamed to a diameter of approximately 19 inches and a depth of 50 feet. 14-inch I.D. SCH40 surface casing shall be installed to a depth of 50 feet and the annular space shall be sealed with neat cement grout or bentonite cement grout. 3. The final design depths and details, including screen location, shall be determined by the ENGINEER after analysis of the results of the pilot hole testing program. 4. NSF approved sodium bentonite shall be employed as drilling fluid. Should lost circulation or other drilling conditions require the addition of bentonite, lost circulation materials, or other such materials, the addition of these materials shall be made only upon approval of the ENGINEER. CONTRACTOR is cautioned to maintain the minimum viscosity of the drilling fluid that will raise cuttings and adequately condition the walls of the holes. Procedures shall be adapted to ensure the removal of any additives during development. 5. In the event that lost circulation conditions are encountered during the drilling process, immediate remedial action shall be taken by CONTRACTOR to restore circulation of the drilling fluid. Conventional techniques for restoring circulation shall be employed. Cementing, except under extraordinary conditions, shall not be employed below the projected static water level. Only materials acceptable in typical water well drilling shall be used to control loss of circulation. These materials shall be approved by the ENGINEER prior to use. 6. The remaining pilot hole shall be reamed to a 13 5 / 8 -inch diameter to a depth of 450-feet. The ENGINEER may, however, direct the reaming to a greater or lesser depth if found advisable after review of the results of the pilot hole program. 7. Installation of Well Casing, Screen and Filter Pack: a. CONTRACTOR shall be responsible for installing the water production well casing, screen, and filter pack such that no damage will result and the intended design criteria are met. If for any reason the installation cannot be made in the correct position or at a depth acceptable to the ENGINEER, CONTRACTOR shall construct another well in a location selected by the OWNER and complete this well in accordance with this Section, at no additional cost to the OWNER. The abandoned hole shall be sealed, as directed by the ENGINEER, in writing, at CONTRACTOR S expense. If any of the casing or screen should collapse prior to water production well completion, it shall be withdrawn and replaced at CONTRACTOR S expense. b. Installation of gravel pack: 1) Prior to placement of the gravel pack, the return line from the mud pit will be sealed off and the drilling fluid shall be thinned with clean water to the satisfaction of the ENGINEER. Gravel pack shall be installed in the annular space as shown. 11

12 The gravel pack shall be carefully installed to ensure complete filling of the annular space from the bottom of the borehole to a level 10 feet above the top of the well screen. 2) During the entire gravel packing operation, thinned drilling fluid shall be circulated down the annular space outside of the well screen and out through the perforations in the well screen into the well hole. As the gravel pack is placed, it shall be disinfected by adding sodium hypochlorite solution. As the gravel pack settles, more shall be added. This operation shall be continued until there is no further measurable settlement of the gravel pack, and the gravel pack has been washed clean. 3) Gravel pack material shall be placed in the bottom of the borehole by a tremie pipe that is gradually withdrawn as the material is placed. If necessary, pumping of the gravel pack material through the tremie pipe shall be performed. Upon completion of this operation, and after removal of the swab, all rock, sand and foreign materials shall be removed from the casing by air lifting. 4) The volume of gravel pack used shall be not less than the calculated volume of the annular space between the casing and the wall of the hole based upon the caliper survey. A quantity less than the computed volume will be judged as an indication of voids and corrective measures shall be undertaken by CONTRACTOR at his own expense. CONTRACTOR shall supply the devices required for measuring the level of the gravel pack. c. Installation of bentonite grout seal and formation stabilizer: 1) A bentonite grout seal shall be installed in the well annulus to fill the void between the casing and borehole from the top of the filter pack to a depth of 100 BLS. The bentonite seal shall be discretely placed above the gravel pack using a positive displacement grout pump and tremie pipe that is gradually withdrawn as the material is placed. d. Installation of neat cement grout seal: 1) A cement grout seal shall be placed from the top of the bentonite seal to completely fill the annular space between the well casing and the borehole within the interval from 100' BLS to 0' BLS. The grout seal mix shall be neat cement or bentonite-cement grout and conform to the requirements of this Section. The seal shall be effective against infiltration of all water. 2) Installation of the cement grout seal shall be accomplished by pumping through a tremie pipe inserted in the annular space between the casing and the borehole. The cement grout seal shall be placed in one continuous operation from 100 BLS to 0 BLS, forming a continuous seal. CONTRACTOR shall be responsible to maintain an equalization of pressures to the extent necessary to prevent collapse of the well casing. 12

13 3) The tremie pipe shall be lowered to within two feet of the bottom of the zone to be grouted. The tremie pipe shall be slowly withdrawn as the annulus fills with grout, but care shall be taken to ensure that the discharge end of the tremie pipe remains submerged a minimum of five feet in the grout at all times while grouting operations are in progress. After the grout has been placed, it shall be allowed to cure for a period of at least 24 hours. 4) CONTRACTOR shall be responsible for circulation of air or water within the well casing to prevent hydraulic collapse during grout curing. B. Method of Water Production Well Construction: 1. The pilot hole shall be reamed to 13 5 / 8 -inch diameter to a depth of 450 feet. The ENGINEER may, however, order the reaming to a greater or lesser depth if found advisable after review of the results of the pilot hole program. 2. The lengths of the screen and casing to be installed in the borehole shall be as directed by the ENGINEER. a. Surface casing may be bell-end or coupled, and solvent welded. b. Well casing shall be field assembled Certainteed Certa-Lok (or approved equivalent) 6.9 nominal O.D. bell-end SDR17 PVC, using spline & groove connections. Solvent weld well casing connections will not be approved. Each connection shall have watertight gaskets or o-rings. c. Screen & blank sections shall be field welded. The ends of each length of screen shall be machine-beveled perpendicular to the screen axis to ensure straightness of each assembled section. Both ends of each screen section shall be furnished with a factory-welded collar 1/4-inch thick and having a minimum width of 1.5-inches. Collars shall be of the same physical and chemical properties as the screen and shall be rolled to fit the screen s outside diameter. The inside edge of the collars shall be ground or sufficiently scarfed to remove sharp edges or burrs. Blank sections within the water bearing zone shall be 6-inch I.D slot or tight-wind 304 stainless steel well screen, as described above. d. Field welding of the screen sections shall be by lap welding with a continuous 1/4-inch fillet weld. All welding shall be performed in accordance with the American Welding Society Standards. e. Well screens shall be assembled to the well casing using an appropriate Certainteed Certa-lok SDR 17 PVC 6.9 x reducing coupler (or approved equal), coupled to a inch (6-inch pipe size) 304 stainless steel grooved adapter. f. The screen and casing assembly with centralizers shall be constructed and suspended in the center of the reamed borehole using a casing clamp. The assembly is to be suspended in the borehole to ensure that it is not supported from the bottom. A rounded cap of similar thickness and material shall be welded to lower end of the screen. Assembled well screens shall be straight, round and have a consistent inner diameter. After the casing and screen assembly is properly suspended in the reamed borehole, filter packing operations shall begin. 13

14 g. a 1.25 O.D. 304 stainless steel monitoring tube shall be welded immediately above the uppermost well screen, and extend to approximately 2 above grade. The monitoring tube shall be assembled with stainless steel threaded couplings, and connected to the 6.25-inch stainless steel grooved adapter using a welded elbow. The monitoring tube shall be secured to the well casing using stainless steel straps. The monitoring tube shall be installed in such a manner that it provides an accurate measurement of pumping and static water levels within the well following well completion. 3. The drilling fluid properties shall be approved by the ENGINEER prior to introduction of the filter pack. Before the filter packing operations begins, CONTRACTOR shall make adequate preparations to ensure that circulation of clear water can be maintained on a continuous basis throughout the operation. 4. Filter pack material shall be placed in the bottom of the borehole by tremie pipe, which will be gradually withdrawn as the material is placed. Pumping of the filter pack material through the tremie pipe shall be performed, if necessary, at no cost to the OWNER. During the filter packing operation, clean water shall be circulated through the screen. As the filter pack is placed, it shall be disinfected with sodium hypochlorite solution. A careful record shall be maintained of the amount of material added during placement and consolidation. The volume of filter pack material used shall not be less than the calculated volume of the annular space between the casing and the wall of the borehole. A quantity less than the computed volume will be judged as an indication of voids and corrective measures shall be undertaken by CONTRACTOR at CONTRACTOR S own expense. CONTRACTOR shall supply the devices required for measuring the filter pack. C. Well Development by Air Lifting, Swabbing and High Velocity Jetting: 1. The first stage of development shall occur after the placement of the filter pack to a level selected by the ENGINEER. Development shall be by air lifting. CONTRACTOR shall employ a suitable device to measure the level of the filter pack in the annulus during development. CONTRACTOR shall take measures to ensure that well development runoff is managed in a manner to not flood offsite properties or roadways. 2. Following well completion by grouting of the well casing, the CONTRACTOR will continue to develop the well by swabbing and jetting. CONTRACTOR shall ensure that swabbing and jetting is performed adequately across the entire screened interval. Swabbing and jetting will continue until development water indicates that the well is free of sand, silt, drilling fluid or other deleterious materials. Upon completion of swabbing all sand, silt, and other foreign material shall be removed from the bottom of the well. 3. CONTRACTOR will submit details on how he intends to perform this operation including equipment specifications. The development will begin at the bottom of the well and proceed upward. CONTRACTOR may use an NSF approved phosphate-free dispersant as recommended by the drilling fluid manufacturer, such as Baroid IDP Aqua-Clear PFD (or approved equivalent material) to aid in dispersion of the drilling fluid. 14

15 D. Well Completion: 1. A bentonite grout plug shall be placed on top of the filter pack material at the end of development. A tremie pipe inserted in the annulus between the well casing and the reamed borehole shall be used to install the plug. The bentonite plug shall extend from the top of the gravel pack to a minimum depth of 100 feet BGS. 2. The well shall be completed with a cement grout extending from a minimum depth of 100 feet BGS to the surface. Neat cement or bentonite cement grout may be used. A tremie pipe inserted in the annulus between the well casing and the reamed borehole shall be used for grouting. Final grouting shall be performed in one continuous lift. The CONTRACTOR shall provide a minimum of 48- hours notice to OWNER, ENGINEER and the Virginia Department of Health prior to grouting. E. Development by Pumping and Surging: 1. CONTRACTOR shall furnish, install, operate, and remove a electric submersible pump for further developing the well. The pump shall be operational between 50 gpm and 100 gallons per minute against a total head of 400 feet at a setting of 325 feet. CONTRACTOR shall furnish and install discharge hose or piping for the pumping unit of sufficient size and length to conduct water to a point designated by the ENGINEER. CONTRACTOR shall also furnish, install and operate acceptable orifices, meters or other ENGINEER approved devices, which will accurately measure the flow rate. A sounding tube shall be installed to a depth designated by the ENGINEER to allow water levels to be easily measured by CONTRACTOR. 2. The initial pumping rate shall be restricted and as the water clears shall be gradually increased until the maximum rate is reached. The maximum rate will be determined by the ENGINEER after consideration of the well's drawdown and discharge characteristics. At proper intervals the pump shall be stopped and the water in the pump column shall be allowed to flow back (surge) through the pump bowls and the screen area. 3. CONTRACTOR shall repeat the cycle of pumping and surging until, in the opinion of the ENGINEER, the following conditions have been properly met: a. Sand production shall be less than 15 parts per million (ppm) within 20 minutes after commencement of pumping at the production rate selected by the ENGINEER. Average sand production shall not exceed one ppm for a two-hour cycle at that production rate. Sand production shall be measured by a Rossum Sand Tester, which shall be properly installed at the wellhead, by CONTRACTOR. b. The discharged water is clear of sand, silt and mud. c. There is no increase in specific capacity during at least 24 hours of continuous pumping and surging. F. Plumbness and Alignment: 1. CONTRACTOR shall perform a test for plumbness and alignment in accordance with AWWA A-100 of the well casing prior to acceptance of the water production well by the ENGINEER. The test shall be performed by lowering a plummet or cage from the surface to the depth at which the cone reducer is installed and measuring deviations from the vertical axis at ten foot depth intervals. 15

16 The plummet or cage shall be at least one foot long and have a minimum outside diameter 1/2-inch smaller than the inside diameter of the casing. The test may be performed by CONTRACTOR at any time after the water production well casing is permanently set. The results of the test shall be analyzed by CONTRACTOR, and a plot of deviations versus depth in east-west and north-south orientations prepared and presented to the ENGINEER to document compliance with these requirements. In order to meet the requirement for plumbness and alignment, it is expected that CONTRACTOR shall exert careful control on drilling rates and bit weights and shall perform alignment tests at his own expense during the construction operations. Should the water production well fail to meet the requirements for plumbness and alignment, it shall be corrected by CONTRACTOR, or a new acceptable well drilled, at no additional cost to the OWNER. 2. To meet the test for alignment, the axis of the water production well casing shall not deviate from the vertical in excess of two-thirds the inside diameter of the casing per 100-feet of depth and the deviation shall be reasonably consistent regarding direction. G. Water Production Well Production/Recovery Testing: 1. Following water production well completion, the water production well shall be production tested to select the design production rate and to determine the drawdown at that rate. CONTRACTOR shall utilize the pumping equipment and measuring equipment described in Paragraph 3.2.E.1., above, to perform the production testing. CONTRACTOR shall be responsible for making all measurements of flow and water level during the test at the intervals selected by the ENGINEER, and shall provide a minimum of 2 devices for measurement of each flow and water level (ex: turbine meter & orifice weir for flow, pressure transducer & electric water level tape for depth). These measurements shall also encompass a 24-hour period at the end of the production test to measure recovering water levels. CONTRACTOR is responsible for providing a portable electric generator for provision of power to the new well test pump. CONTRACTOR shall, upon completion of testing, deliver a certified copy of the development and test records to the ENGINEER. The CONTRACTOR shall pump the new production well at a rate of approximately 100 gpm period of 24 hours. CONTRACTOR shall be responsible for making all measurements of flow and water level during the test at the intervals selected by the ENGINEER, and shall provide a minimum of 2 devices for measurement of each flow and water level (ex: turbine meter & orifice weir for flow, pressure transducer & electric water level tape for depth). These measurements shall also encompass a 24-hour period at the end of the production test to measure recovering water levels. CONTRACTOR is responsible for providing a portable electric generator for provision of power to the test pump at the new production well. CONTRACTOR shall, upon completion of testing, deliver a certified copy of the development and test records to the ENGINEER. 16

17 1. CONTRACTOR shall be responsible for conducting all pumping test water away from the site in a manner such that water does not pond on the site or on adjacent residential parcels. CONTRACTOR shall ensure that adequate erosion control measures are incorporated to disperse the test water and minimize erosion. Evaluation of the pump test water management is entirely at the discretion of the ENGINEER or OWNER. H. Water Quality Testing: 1. During the final 12 hours of the pumping test, the CONTRACTOR shall collect 20 samples for Total Coliform & E. Coli, MPN from the new well. The samples shall be collected from a sampling tap at the wellhead at one hour intervals. During the final hour of the pumping test, the CONTRACTOR shall collect a New Well Series of samples as required by VDH. All samples shall be collected by approved methods into laboratorysupplied containers, and analyzed by a Virginia DCLS-certified testing laboratory. 2. The New Well Series production well sampling shall consist of the following: a. Nitrate/Nitrite I. Disposal of Drilling Fluid and Drill Cuttings: 1. Due to the limited size of the site as well as the proximity to potential wetlands and residences, all drilling fluid and cuttings must be contained and removed from the site. In no instance shall drilling fluid be discharged intentionally or accidentally off the property. CONTRACTOR bears the sole responsibility and liability for damages or citations resulting from discharge of drilling fluid from the site. 2. Drilling fluid shall be disposed of by means acceptable to OWNER, and in compliance with any local, state & federal rules and regulations. CONTRACTOR is responsible for all costs associated with drilling fluid disposal. J. Disinfection: 1. Prior to production testing of the well, CONTRACTOR shall begin disinfection of the well. To disinfect the well, CONTRACTOR shall use a sodium hypochlorite (NaOCl) solution to provide a minimum 100 parts per million (ppm) of available chlorine concentration throughout the entire saturated depth of the well and to disinfect the well casing above the water level. a. The solution shall be delivered to the Site in original closed containers bearing the original label indicating the percentage of available chlorine. The solution shall not have been stored for more than 60 days. During storage, the solution shall not be exposed to the atmosphere or to direct sunlight. 17

18 b. The NaOCl solution shall be mixed with approximately 1000 gallons of potable water on-site and introduced into the water production well through an appropriate tremie device such that the solution is equally dispersed within the entire water depth of the water production well. After introduction of the disinfectant, the solution shall be thoroughly mixed in the water production well by surging with a swab or other similar tool from the bottom of the water production well to the water surface or surging with the test pump. The solution shall remain in the water production well for at least 24 hours during which time the water production well should be surged at two hour intervals. If the test pump is in the water production well, the water production well shall be pumped at the end of the 24-hour period and the discharge diverted to flow back into the water production well to thoroughly flush the inside of the casing and the column pipe for a period of least 30 minutes. If the test pump is not in the water production well, CONTRACTOR shall devise an acceptable method for thoroughly disinfecting the portion of the water production well casing above the water surface with the solution. K. Close-Out Procedures: 1. Prior to removal of the test pump, the CONTRACTOR shall submit laboratory results of the 20 bacteriological samples collected during testing. The geometric mean of the MPN results shall be less than 3, as calculated by the ENGINEER. If the geometric mean of the bacteriological results are 3 or greater, the CONTRACTOR shall repeat the disinfection process, and an additional 20 MPN samples shall be collected. CONTRACTOR shall be responsible for all costs associated with additional disinfection, sample collection and sample analysis 2. CONTRACTOR shall remove all debris, excess materials, and ensure final grading and return of Site to the original condition, to include adequate backfilling and compaction of mud pits and any other excavations at the site. 5. Upon final completion and acceptance of the completed well by the OWNER, CONTRACTOR shall secure the well with a removable 6.9-inch O.D. SDR17 PVC Certa-Lok (or approved equivalent) casing cap, and secure the monitoring tube with a removable 1.25-inch threaded cap or plug. + + END OF SECTION