A24_AMENDMENT_233_27_15.pdf

SECTION 33 27 15

RELIEF WELLS

PART 1 GENERAL

1.1 SCOPE

This section, in conjunction with the contract drawings, covers new relief wells in their entirety including well drilling, well screen, riser pipe, filter pack, well development, and pumping tests and outlet works. All work shall conform to the requirements of the Missouri Water Well Construction Rules. Any permitting, licensing, and submittal requirements required by this Act are the responsibility of the Contractor.

1.2 QUALITY CONTROL

1.2.1 General

The Contractor shall perform the inspection, sampling and testing, corrective actions, and submit the required reports to substantiate compliance with SECTION 01 14 40 - CONTRACTOR QUALITY CONTROL.

1.2.2 Inspection

The Contractor's quality control organization shall be responsible to observe and control, for compliance with the technical specifications, all relief well construction and repair including but not limited to the following: maintain Government survey layout, materials, drilling method, joints, bottom plug, materials storage, well pipe assembly and installation, backfilling, cleaning, development, pumps, pump testing, earthwork, discharge channels and safety. Completed relief wells shall be protected against damage and contamination.

1.2.3 Sampling and Testing

The Contractor's quality control organization shall verify that all relief well materials conform to these specifications before delivery to the project.

1.2.4 Action Required

When quality control monitoring or testing detects non conformance with specifications, corrective action shall be directed. The details of the irregularities and the actions directed to correct them shall be reported immediately to the representative of the Contracting Officer and included in the daily Quality Control report. Corrective action shall include steps taken to assure against recurrence of the irregularity.

1.2.5 Reports

Reports shall include, for each new relief well, ENG form 1836 "Drilling Log", WES Form 797 "Relief Well Installation Report", WES Form 796 "Relief Well Pumping Test Report", and ENG Form 2087 "Gradation Curves" for filter pack samples. A copy of each report form is attached at the end of these specifications. The driller shall complete a detailed log for each new well. The report on relief well backfill material shall include the filter pack particle size distribution. Data concerning installation and development of the relief wells shall be included in the report on relief well installation. A "Relief Well Pumping Test Report" shall include those items listed in paragraph Data for each new relief well. Results of relief well repair work shall be submitted on a daily basis as work progresses.

The reports shall be completely filled out and shall be submitted to the Contracting Officer as part of the daily quality control report specified in SECTION 01 14 40 - CONTRACTOR QUALITY CONTROL.

1.3 APPLICABLE PUBLICATIONS

All publications referenced shall be the most current version, edition, standard, latest revision, or reapproval unless otherwise stated. The following publications listed below, but referred to thereafter by basic designation only, form a part of this specification to the extent indicated by the references thereto:

Department of the Army, Corps of Engineers, Engineer Manuals

EM 1110 2 1906 Laboratory Soils Testing, November 1970

EM 1110-2-1914 Design, Construction, and Maintenance of Relief Wells

American Society For Testing and Materials (ASTM)

A 312/A312M Seamless and Welded Austenitic Stainless Steel Pipes

ASTM B 98 Copper-Silicon Alloy Rod, Bar, and Shapes

C 117 Materials Finer Than 75 UM (No. 200) Sieve in Mineral Aggregates By Washing

C 136 Sieve Analysis of Fine and Coarse Aggregates

D 422 Particle Size Analysis of Soils

D 698 Laboratory Compaction Characteristics of Soil Using Standard Effort

D 1556 Density and Unit Weight of Soil in Place by the Sand Cone Method

D 2167 Density of Soil in Place by the Drive Cylinder Method

D 2487 Classification of Soils for Engineering Purposes

D 4253 Maximum Index Density and Unit Weight of Soils Using a Vibratory Table

D 4254 Minimum Index Density and Unit Weight of Soils and Calculation of Relative Density

F 480 Thermoplastic Well Casing Pipe and Couplings Made in Standard Dimension Ratios (SDR), Sch 40 and Sch 80

The Aluminum Association (AA)

AA SAS 30 Aluminum Construction Manual Series Section 1 Specifications for Aluminum Structures

American Welding Society (AWS)

D 1.1 Structural Welding Code - Steel

Missouri Department of Natural Resources, Division of Geology and Land Survey

MDNR Missouri Well Construction Rules, Miscellaneous Publication No. #50

Missouri Standard Specifications (MoDOT)

MODOT Missouri Standard Specifications for Highway Construction

Well Drilling Industry Publications

WDIP Ground Water and Wells, 2nd Ed., Johnson Filtration System, Inc.

1.4 SUBMITTALS

Government approval is required for submittals with a "GA" designation;

submittals having an "FIO" designation are for information only. The following shall be submitted in accordance with SECTION 01 33 00 -

SUBMITTAL PROCEDURES.

SD-01 Preconstruction Submittals

Well Drilling Specialist; G

SD-02 Shop Drawings

Shop Drawings; G

1.5 SUBMITTAL DESCRIPTIONS

1.5.1 Shop Drawings

The Contractor shall submit to the Contracting Officer, shop drawings which present details of the proposed methods for drilling, coupling well screen and riser sections, installing well screen and riser, backfilling, developing, and pump testing. The shop drawings shall show the well screen material, dimensions, slot size, shape, pattern, bottom, and installation details. The riser pipe and well housing details shall also be shown on the shop drawings. The shop drawing submittal shall include a Schedule of Materials describing the length of each section of well screen and riser pipe used to meet the total lengths specified for each well. Any Contractor proposed substitutes or alternates in material construction details or methods shall be indicated on the submittal and detailed on the shop drawings. No phase of the work shall be initiated until all shop drawings concerning that activity have been approved.

1.5.2 Well Drilling Specialist

The Contractor shall submit to the Contracting Officer, for review and approval within 10 days of Notice to Proceed, summaries of qualifications and references for the Well Drilling Specialist. Well drilling shall not proceed until the well drilling specialist has been approved by the Government.

1.6 LOCATION Relief well locations shall be field located by the Contracting Officers' representative before any drilling can begin. The final relief well locations may be adjusted by the Contracting Officer at no additional cost to the Government.

1.7 DISPOSAL OF DEBRIS The Contractor shall dispose of all debris resulting from relief well construction operations off-site. Disposal activities shall be in compliance with SECTION 01 11 30 - ENVIRONMENTAL PROTECTION.

1.8 SUBSURFACE DATA Subsurface soil boring logs are shown on the drawings. These data represent the best subsurface information available; however, variations may exist in the subsurface between boring locations. Groundwater levels indicated in the soil boring logs were at the time of exploration. The groundwater table may vary significantly depending on time of year and river stage level.

PART 2 PRODUCTS

2.1 WELL SCREEN AND RISER PIPE

2.1.1 General

Well screen, screen interval and riser length will be determined by the Contracting Officer. Materials for relief wells shall be of the type specified below, and shall be of the dimensions specified by the Government. Screen openings shall be uniform in size and pattern, and shall be spaced approximately equally around the circumference of the pipe. Before installation, all well-screen shall be approved by the Contracting Officer.

2.1.2 Stainless Steel Well Screen

2.1.2.1 General

The well screen shall be of the continuous slot, wire-wound design. It shall be fabricated by circumferentially wrapping a triangularly shaped wire around a circular array of internal rods. The wire configuration shall produce inlet slots with sharp outer edges, widening inwardly to minimize clogging. Each juncture between the horizontal wire and the vertical rods shall be fusion welded under water by the electrical resistance method.

End fittings shall be welded to the screen body.

2.1.2.2 Materials

All pipes, rods, bars, wire, and fittings shall be stainless steel conforming to ASTM A 312, Grade TP 304.

2.1.2.3 Well Screen

The width of the clear space between the wire wrappings and the screened interval shall be determined by the Contracting Officer and given to the Contractor before the issuance of the Task Order to complete the relief well installation. Each screen length identified will refer to the actual length of exposed open area. Collapse, column, and tensile strengths of the well screens shall be adequate to allow safe installation and development of the wells. In addition, each well shall contain 2 five-foot sections of screen to allow for field changes during installation, if necessary.

2.1.2.4 Well Screen Coupling

End fittings for the stainless steel well screens shall be furnished with Schedule 40 flush threads compatible with ASTM F 480 requirements, and of the same alloy as the well screen and riser pipe. Flush joint fittings which join well screen to riser pipe shall adequately provide for the transition from well screen to riser pipe. Joints shall be designed and constructed to support the weight of the screen and/or pipe as it is lowered into the hole. All fittings shall contain a Viton O ring on the male end.

2.1.3 Stainless Steel Riser Pipe

The new relief well riser pipe and fittings shall be manufactured from stainless steel conforming to ASTM A 312, Grade TP 304. The pipe roundness, wall thickness, and straightness shall meet the ASTM specifications. The riser pipe shall be Schedule 40 wall thickness with a minimum inside diameter of 10 inches. Riser discharge shall conform to the details shown on the contract drawings. Couplings for new relief wells between the riser pipe and the well screen and between adjacent pieces of riser pipe sections shall be as specified for well screen pipes.

2.1.4 Bottom Plug for Well Screen

The bottom plug for each well screen shall be made of the same material and at least the same minimum thickness as the screen. Plugs shall be the same diameter as the outside of the screen and fastened to the bottom screen portion in an approved manner.

2.2 FILTER PACK MATERIALS

2.2.1 General

Material for the filter pack around the riser pipes and screens shall be a washed sand composed of hard, noncarbonate, tough, and durable particles free from adherent coating. The filter pack material shall contain no detrimental quantities of organic matter or soft, friable, thin, or elongated particles. Filter pack materials shall be uniformly graded, with a coefficient of uniformity less than 2.0.

2.2.2 Particle Size Distribution

2.2.2.1 General

The particle size distribution of the filter pack shall be sampled and tested by the Contractor using the U. S. Standard Sieve nomenclature. There shall be one particle size distribution test for the filter pack material used in each well. No later than 48 hours before being placed in the relief well, the particle size distribution of the filter pack shall be determined from a sample obtained from the material stockpiled and the results supplied to the Contracting Officer. The filter pack material and its gradation shall be approved by the Contracting Officer before it is placed in the well.

2.2.2.2 Variance

Filter varies per well as indicated below:

FOR RF 30

U.S. Standard Percent by Weight Sieve No. Passing No. 10 100 - 93 No. 12 100 - 87 No. 14 80 - 66 No. 16 57 - 43 No. 18 30 - 16 No. 20 17 - 0 No. 30 7 - 0

FOR RF 40

U.S. Standard Percent by Weight Sieve No. Passing No. 8 100 - 93 No. 10 100 - 91 No. 12 95 - 81 No. 14 62 - 48 No. 16 31 - 17 No. 18 11 - 0 No. 20 8 - 0 No. 30 7 - 0

FOR RF 60

U.S. Standard Percent by Weight Sieve No. Passing No. 4 100 - 93 No. 6 100 - 90 No. 7 91 - 77 No. 8 75 - 61 No. 10 43 - 29 No. 12 14 - 0 No. 14 8 - 0

2.2.2.3 Grading Curves

The laboratory test procedure shall conform to that presented in ASTM C 136.

All points on individual grading curves obtained from representative samples of filter material shall lie between the boundary limits as defined by smooth curves drawn through the tabulated grading limits plotted on a mechanical analysis diagram. The individual grading curves within these limits shall not exhibit abrupt changes in slope denoting skip grading, scalping of certain sizes, or other irregularities, which would be detrimental to the proper functioning of the filter.

2.3 RELIEF WELL OUTLET WORKS

The outlet works shall conform to the requirements specified below.

2.3.1 "D"-Type Wells

The outlet works shall consist of a well guard with checkvalve, coverplate, concrete pad, numbering/welding and other appurtenant items.

2.3.1.1 Well Guard

The well guard shall consist of a section of 20-inch diameter, stainless steel Type 304, and continuous slot well screen. End fittings shall be welded to the screen body. Welding rings shall be furnished on both ends of the screen and stainless steel 3x3 angles (4) welded to the weld rings. The guard screen shall be attached to the concrete pad by bolting of well guard by the angles to the embedded bolts of the concrete pad as shown on the drawings.

2.3.1.2 Concrete Pad

Dimensions and details of the concrete are shown in the drawings.

Requirements for the concrete are contained in SECTION 03 33 10 - RELIEF WELL

CONCRETE.

2.3.1.3 Check Valve

The check valves shall be fabricated in accordance with details shown on the drawings and as specified herein. The aluminum parts, at the Contractor's option, may be any one or a combination of aluminum alloys 3005 H14, 6061 T 4, or T6. The 3/8 inch diameter aluminum guide rods shall be carefully bent to avoid flattening at the bends. The seat for the check valve shall be constructed of two 1/4-inch aluminum plates and a neoprene gasket, all bolted together as indicated on the drawings. The bolt holes shall be formed by drilling or punching the aluminum plates and neoprene gasket. The neoprene gasket shall have a thickness of 1/2-inch and shall be fabricated from solid neoprene gasket material. The aluminum guide rods and aluminum lifting ring shall be connected to the plates by welding conforming to the applicable provisions of the AA Specification AA SAS 30.

2.3.1.4 Cover Plate

The top of the well guard shall be fitted with a detachable Type 304 stainless steel cover plate as shown on the drawings. The plate shall be 1/4-inch in thickness and shall have a diameter of 21 inches. The cover plate shall be attached to the well guard using brass 5/8-inch bolts, and stainless steel washers and nuts. The nuts shall be tack-welded onto the underside of the angles attached to the weld ring of the outlet works.

2.3.1.5 Numbering

On all new "D"- Type well guards installed, the well number shall be bead-welded onto a stainless steel plate. The numbered plate shall be ¼-inch thick and 6-inches in length. The numbered plate shall be tack-welded onto the upper side of the outlet works, facing the levee crown.

2.4 CRUSHED STONE MATERIAL

Crushed stone aggregate shall conform to all the requirements stated in the Missouri Department of Transportation (MoDOT), Type 2 for coarse aggregate.

PART 3 EXECUTION

3.1 DRILLING

3.1.1 General

The Contractor shall designate a well drilling specialist for each work shift. The well drilling specialist shall have a minimum of five years experience in the water well industry, and shall be familiar with the operation of all equipment and machinery required to install high-capacity water wells in Mississippi River alluvium. The Contractor shall submit summaries of qualifications and references for any and all well drilling specialists to the Government for review and approval within 10 days of Notice to Proceed. Well drilling shall not proceed until the well drilling specialist has been approved by the Government. The well drilling specialist shall be at the field site at all times during drilling, installation of well materials, or development of installed wells. Wells shall be drilled by the reverse rotary method, in such a manner to ensure proper placement of the well screen, riser pipe and filter pack. Drilling and installation of well screen and filter pack shall be completed for each well without interruption. River stage limitations may be imposed as the river rises to 22 on the Chester Gage. If necessary, the ACO or Contracting Officer will direct the Contractor to perform limited operations or cease operations. The Contractor shall examine the National Weather Service 3-day forecast for the St. Louis Gage daily to be alerted to possible high river stages and to prepare for preventing damage to already completed work. Drill cutting material shall be disposed of as specified in paragraph DISPOSAL OF DEBRIS. All other excavated material shall be disposed of according to SECTION 01 11 30 - ENVIRONMENTAL PROTECTION. Before the drilling operation begins on each well, the Contractor shall demonstrate that all material, equipment, and experienced personnel are mobilized and that all equipment necessary for the job is adequate for an efficient operation and is operating in a satisfactorily manner. Loss of a hole or well because of lack of material, inadequate or faulty equipment, or careless operating procedures will be considered cause for an abandoned well due to fault of the Contractor. The digging of mud pits or similar excavations will not be allowed.

3.1.2 Temporary Casing

A new or used temporary well casing of either iron or steel may be used to support the sides of the entire hole during drilling and placement of screen, riser pipe, and filter pack and to support the sides of the unbackfilled portion of the hole during development of the well. Any temporary casing shall have an inside diameter large enough to provide the minimum filter thickness, as specified in paragraph PLACING FILTER PACK, entirely around the well screen or riser pipe and shall have sufficient thickness to retain its shape and maintain a true section throughout its depth and may be in sections of any convenient length. The temporary casing shall be securely anchored to the drill rig or ground surface at all times until removed. The temporary casing shall be such as to permit its removal without interfering with the filter or riser pipe. Methods of installation, which will create a cavity outside the temporary casing, will not be permitted.

3.1.3 Obstructions Encountered

The Contractor may encounter the presence of cobbles/boulders and/or in-situ wood. Contractor shall have multiple methods available to advance the hole passed all obstructions and achieve the depths required for the well. The presence of cobbles/boulders or in-situ wood, which may be encountered during drilling, shall not be considered as obstructions or sufficient reason for abandonment of a well. Where obstructions are encountered, drilling shall be continued using all means and methods, until it is demonstrated to the USACE Contracting Officer that further efforts to advance the drill hole are impracticable. If rendered impracticable, the Contracting Officer may adjust the depth to conform to that of the obstruction or may direct the Contractor to abandon the well as specified in paragraph RELIEF WELL ABANDONMENT and construct another at an adjacent site. At no time will circulation continue with no advancement, for longer than 30 minutes.

3.1.4 Temporary Drilling Pads

The Contractor shall construct any required drilling pads at the expense of the contractor to the minimum dimensions needed to perform the work in a safe manner. Material used in the construction of the pads shall consist of crushed stone meeting the requirements of paragraph CRUSHED STONE

AGGREGATE.

3.1.4.1 CRUSHED STONE AGGREGATE

Crushed stone aggregate shall conform to all the requirements stated in the Missouri Department of Transportation (MoDOT), Type 2 for coarse aggregate.

3.2 INSTALLATION OF RISER PIPE AND SCREEN

3.2.1 Assembly

All riser pipe and screen shall be in new and good condition before installation and all couplings and other accessory parts shall be securely fastened in place. The successive lengths of pipe shall be arranged to provide accurate placement of the screen sections in the soil strata. The bottom of the screen and riser assembly shall be equipped with an appropriate centering guide which will satisfactorily center the riser pipe and screen in the well and will hold it securely in position while the filter pack material is being placed.

3.2.2 Joints

Sections of relief well pipe shall be joined together as specified in paragraph Well Screen Coupling. Joints shall be designed and constructed to have sufficient strength to support the weight of the relief well string as it is lowered into the hole.

3.2.3 Installation

The assembled riser pipe and screen shall be placed in the hole in such manner as to avoid jarring impacts and to ensure that the assembly is centered and not damaged or disconnected. After the screen and riser pipe have been placed, a filter pack shall be constructed around the screen section as specified in paragraph PLACING FILTER PACK and the well developed as specified in paragraph DEVELOPMENT. The top of the riser pipe shall be held at the designated elevation during placement of the filter pack. The top of the riser pipe shall stick up 6 inches above the bottom of the manhole when the well is completed.

3.2.4 Verticality

Each well shall be installed and maintained straight and plumb during placement of filter and development. Immediately before placing the filter pack and with the top of the well fastened securely in a vertical and horizontal position, the Contracting Officer may elect to perform verticality tests to check alignment and plumbness. This test, if performed, will be performed using approved methods to verify the verticality of the well. This test, if performed, will be performed by Government personnel with Government owned equipment. A variation of 12 inches per 100 feet will be permitted in the combined length of screen and riser pipe of the well. If the well fails to conform to the standard described above, the plumbness of the well shall be corrected by the Contractor at no additional expense to the Government.

3.3 PLACING FILTER PACK

3.3.1 General

After the screen and riser pipe have been placed, and alignment surveys and plumbness surveys (if performed by the Government) are conducted, the check valve shall be placed on the top of the well riser to prevent any material from entering the interior of the well. The Contractor shall place the filter pack using the tremie method or an approved alternative which prevents segregation. The filter pack shall be disinfected during placement per applicable state regulations.

3.3.2 Tremie

3.3.2.1 Tremie Hopper

The filter pack shall be placed in a tremie hopper so constructed and balanced that filter material will feed freely and equally to two tremie pipes located at 180 degrees on each side of the screen. Connections between the tremie pipe and the hopper shall be designed for quick connection or disconnection for adding or removing tremie pipe with least possible delay.

B3ECGANG

Polygon

3.3.2.2 Tremie Pipes

Tremie pipe shall consist of two rigid 4 inch inside diameter tremies with no obstructions. The tremie pipes shall consist of equal 5 foot lengths of standard 4 inch pipe with 1/16 inch wide equally spaced slotted openings.

Tremie pipe shall be free of dents, flat spots, damaged threads, and holes, and shall be reamed and/or deburred to full inside diameter of the pipe.

The tremie guide shall consist of a metal ring or rings of sufficient diameter to slip freely over riser pipe and screen with 4 inch collars welded to the guide at 180 degrees to securely hold the tremie pipe in place.

3.3.3 Filter Pack Procedure

The Contractor shall be equipped to quickly and efficiently add filter material to the hopper in any position from the ground surface to the maximum height of the hopper. No filter pack material shall be allowed to enter the well except through the tremie pipes. At no time shall tremie guide or pipes be raised, lowered or supported by only one pipe. Ten feet of tremie pipe shall be installed below the lower tremie guide. The filter pack material shall be placed using clean water introduced at bottom of hopper and without significant segregation.

The filter pack shall have a thickness of 8 inches between the outside of the well screen and the outside of the filter pack and shall be placed to a level 5 feet above the top of the well screen. At the commencement of the placing operation, the tremie shall rest at the bottom of the hole and shall be filled with filter pack material. The tremie shall then be raised in increments approximately equal to the increments of the filter pack placed. At all times during the placing of the filter pack, the tremie shall be kept filled to within five feet of its top.

If temporary casing is used, the filter pack shall be placed in increments not to exceed 2 feet; the tremie and temporary casing shall be raised in small increments approximately equal to the increments of the filter pack placed, except that at no time prior to the completion of placement of the filter pack shall the bottom of the casing be less than 1 foot below the top of the filter pack in the hole. The Contractor shall provide a means of measuring the filter pack depth in the hole. The alternate placing of filter pack material and withdrawing of the tremie and temporary casing shall be continued until the filter pack has been placed to the level shown on the drawings.

During development of the well, the top of the filter pack material shall be maintained at the level specified above. Prior to and during placement of the filter pack, the top of the temporary casing or hole shall be covered or otherwise shielded to prevent the filter pack from entering the space around the well except through the tremie pipe. Material, which may have entered the well screen and riser pipe, shall be removed before development of the well is commenced. Construction of the relief well outlets works or of the backfilling specified in paragraph WELL SEALING shall not commence until the development of the well is completed and the filter pack has been placed to the elevation specified.

3.4 DEVELOPMENT

3.4.1 General

Following placement of filter pack materials the Contractor shall develop the relief well by high velocity jetting and simultaneous airlift pumping.

At the time of development, the well shall be free of drawdown or surging effects due to pump testing, developing or drilling at another location.

The Contractor shall be responsible for maintaining the needed access and work areas at the relief well and the necessary clearance in the relief well to accomplish development. The Contractor shall furnish, install or construct the necessary discharge line and troughs to conduct and dispose of the discharge a sufficient distance from the work areas to prevent damage and contamination of any relief wells. This may require running the discharge lines over the levee and discharging on and splash protection at the toe of the levee on the riverside. Development shall be conducted to achieve a stable well of maximum efficiency and shall be continued until little or no material from the foundation or filter pack can be pulled into the well by pumping. As development proceeds, filter pack material shall be added to the annular space around the screen to maintain the top elevation of the filter pack at the specified elevation. The Contractor shall provide a bubbler tube or other approved means for accurately determining the water level in the well under all conditions. If at any time during the development process it becomes apparent, in the opinion of the Contracting Officer, that the well may be damaged, operations shall be immediately stopped. The Contracting Officer may require a change in method if the Contractor's method does not accomplish the desired results.

If after initial development and 6 hours of additional development, a well continues to produce excess sand, the Contracting Officer may order the Contractor to abandon the well as specified in paragraph RELIEF WELL ABANDONMENT. All materials pulled into the well by the development process shall be removed prior to performing the pumping test.

3.4.2 Jetting and Air-Lift Pumping

The well development shall be accomplished by high-velocity, horizontal jetting and simultaneous airlift pumping. The outside diameter of the jetting tool shall be ½ to 1 inch less than the inside diameter of the screen. The exit velocity of the jetting fluid shall be between 150 and 300 fps and have a pressure at the nozzle of approximately 200 psi.

Circulation of the jetting water will not be allowed. The jetting shall proceed from the bottom of the screen to the top. The tool shall be rotated at a speed of 1 rpm. It shall be positioned at one level for not less than 2 minutes and shall then be raised to the next level. Individual jetting levels shall be spaced no more than 6 inches vertically apart.

Sizing of the eductor pipe, air line, and air compressor shall be adequate to efficiently pump the well at a rate from 10 to 20 percent more than the volume of water introduced through the jetting tool. The eductor pipe shall be placed no more than 5 feet above the top of the jetting tool during development. At the start of the airline pumping the quantity of air injected shall only be sufficient to initiate flow through the screen.

3.5 PUMPING TEST

3.5.1 General

The Contractor shall perform pumping tests to determine whether the new wells have been adequately developed. Development shall continue until the sand content of the discharge, per well, averages no more than 5 milligrams of sand per Liter of discharge water (5 ppm) for a complete pumping cycle of 2 hours duration when pumping at a constant rate of 500 gpm. Sand content measurements shall be taken at equal 15-minute intervals to permit plotting sand content as a function of time and discharge and determination of average content for each cycle. After completion of the test, the depth of the well shall be measured, by means of an approved method, under the direction of a representative of the Contracting Officer.

3.5.2 Equipment

3.5.2.1 Pump

The Contractor shall provide a deep-well submersible pump capable of producing the specified discharge over a period sufficient to satisfactorily perform the pumping test specified. The Contractor shall provide, without additional cost to the Government, the electrical power, control box and the necessary wiring which shall be removed at the completion of the pumping test.

3.5.2.2 Water Level

The Contractor shall provide means for accurately determining the water level in the well to within 0.01 foot, under all conditions.

3.5.2.3 Flow Meter

The Contractor shall furnish and install a calibrated flow meter of standard design for measuring the discharge from the well during the pumping test. The meter shall have an accuracy within 1% of measured flow or better and a turndown ratio of between 4:1 and 8:1. Meter should also be equipped with a totalizing register. The calibration of the flow meter shall be checked at regular intervals.

3.5.2.4 Rossum Sand Sampler

The Contractor shall furnish an approved Rossum centrifugal sand sampler and appurtenant piping and valving for accurate determination of the discharge sand content.

3.5.3 Data

The following test data shall be obtained and recorded by the Contractor on WES Form 796 "Relief Well Pumping Test Report", a copy of which is attached at the end of this section.

(1) Time of water level measurement.

(2) Depth of water in well before, during, and after pumping. The time intervals for measuring the water levels shall be every 15 minutes for the duration of the pumping test.

(3) Flow in gpm and cumulative volume.

(4) Elevation of water in well before and after pumping.

(5) Elevation of water in 4 closest adjacent wells or piezometers before, during, and after pumping.

(6) The depth of sand in well before, during, and after pumping.

(7) Sand content of discharge in ppm plotted against time of pumping.

3.5.4 Pump Test Procedure

The pumping and sand infiltration tests shall be conducted under the direction of the Contracting Officer. The Contractor shall test each well by pumping continuously for a minimum of two hours. The pumping shall be at a constant rate sufficient to produce a discharge of 500 gpm or 10 feet of drawdown, whichever is less. No test pumping of a well will be permitted when wells are flowing or concurrently with drilling or pumping of any other well within a radius of 500 feet. In the event that the test is interrupted, other than by order of :the Contracting Officer, prior to the completion of the specified period of continuous operations, the water level in the well shall be allowed to recover to the original static level and the test shall be re run at no additional expense to the Government.

In addition to the test described above, the Contracting Officer may direct the Contractor to perform additional testing. Such additional testing shall conform in general to the requirements specified above with the exception that the duration of the tests and the approximate drawdown will be determined by the Contracting Officer. The test, to be successful, shall be continuous throughout the specified period.

In the event that sand or other material infiltrates into the well as a result of the pumping test, the following procedure shall be followed: If the rate of sand infiltration during the latter part of the two hour pumping test has not been reduced to 5 ppm or less, the well shall be resurged by manipulation of the test pump for 20 minutes after which the test pumping shall be resumed and shall be continued at the constant rate specified above until the sand infiltration rate is reduced to 5 ppm, but not for more than a total of eight hours.

If, at the end of eight hours of pumping, the rate of infiltration of sand is more than 5 ppm, the well shall be abandoned, except that the Contractor may elect to continue the test pumping and perform such other approved remedial work considered desirable, all at the Contractor's own expense.

If, after such additional test pumping and other remedial measures, the sand infiltration rate of a well is reduced to 5 ppm, the well will be accepted. Unacceptable wells shall be abandoned in accordance with paragraph RELIEF WELL ABANDONMENT and a new well installed nearby at a location directed by the Contracting Officer.

Upon completion of the pumping test, any sand or filter material in the bottom of the well shall be removed by pumping or by other approved methods, after which the Contractor shall remove all equipment, discharge lines, etc., and restore the site to its original condition.

3.5.5 Additional Pumping Test Measurements

In addition to the measurements and record-keeping required of the Contractor, the Government or its representative may require access to the well to perform additional water level measurements in the pumped well and nearby relief wells.

3.5.6 Records

The Contractor shall obtain and furnish to the representative of the Contracting Officer for record purposes the elevation of the water in each well before and after the development pumping, the flow in gpm at the completion of the pumping and the time of observation. The water surface elevation shall be obtained immediately before starting the surge pump and the water surface elevation and flow shall be obtained just before stopping the pump upon completion of the development pumping. This data shall be recorded on WES Form 797, a copy of which is attached at the end of this section.

3.6 WELL SEALING

After each new well has been developed the annular space above the filter pack shall be backfilled by extending the filter pack a minimum of 5 feet above the top of the screen, sealing with a 5 foot seal of bentonite pellets or chips, hydrated and sealing the remainder of the space up to the base of the concrete pad with concrete. Concrete shall conform to the requirements specified in SECTION 03 33 10- RELIEF WELL CONCRETE. The temporary casing, if used, shall be withdrawn in increments as the backfill is placed.

3.7 RELIEF WELL ABANDONMENT

Wells ordered abandoned by the Contracting Officer, shall be sealed to the ground surface with concrete by means of a tremie pipe inserted to the bottom of the well. The tremie pipe may be withdrawn but the end of the grout pipe must remain at least 2 feet below the surface of the concrete.

The concrete shall be placed through the pipe and forced upwards towards the surface. When the concrete reaches the surface, it shall be allowed to flow to waste until the Contracting Officer determines that the sealing has been satisfactorily accomplished. The concrete mix shall consist of that specified in SECTION 03 33 10- RELIEF WELL CONCRETE.