Section J Attachment 2_Geology Supplement for the ECS MATOC_30 OCT 2020.pdf

Rev. Aug. 2020

SECTION J, ATTACHMENT 2 GEOLOGY/HYDROGEOLOGY REQUIREMENTS

8(a) SMALL BUSINESS ENVIRONMENTAL CONSULTING SERVICES (ECS)

MULTIPLE AWARD TASK ORDER CONTRACT (MATOC)

1. Introduction This supplement is intended to serve as the specifications for accomplishing the geology related tasks identified in the Site-specific Scope of Services (SOS), to which this supplement is attached. All work shall be performed in accordance with this supplement unless otherwise specified in the Site-specific SOS. If there are any differences between this supplement and the Site-specific SOS, the Contractor shall implement the Site-specific instructions.

• The Contractor shall disregard all sections of this supplement that do not apply to the tasks as outlined in the Site-specific SOS. For example, if no new monitoring wells are to be installed, then the Contractor has no reason to refer to the sections on monitoring well installation, construction diagrams, etc.

• The Draft Project Report and Final Project Report referenced in this document shall be defined in the Site-specific SOS. If there are any questions regarding this supplement, the Contractor shall contact the U.S.

Army Corps of Engineers (USACE) Project Geologist for clarification.

• Field investigation procedures shall be conducted in accordance with all federal, state, and local requirements. If the specifications as set forth in this SOS do not meet regulatory requirements, contact the USACE Contracting Officer’s Representative (USACE-COR) for resolution of differences. The Contractor is responsible for determining applicable federal, state, and local requirements.

• The Contractor shall provide a qualified geologist or geotechnical engineer who shall be on site and responsible for all logging and sampling during all soil/rock sampling activities. A qualified geologist/geotechnical engineer shall be on site and responsible for all monitoring well drilling, installation, development and testing activities. A qualified geologist/geotechnical engineer is defined as having a baccalaureate degree in a geological science or geological/geotechnical engineering from an accredited university and a minimum of one (1) year experience in logging and/or analysis of subsurface conditions. The qualifications of the on-site geologist and/or geotechnical engineer shall be included in the Contractor work plans. A person meeting these requirements shall be dedicated to each activity. The Contractor shall notify the U.S. Army Corps of Engineers (USACE) representative at least 1 week prior to the initiation of any field investigations so that a USACE representative can plan to be present for field oversight. The Contractor shall notify the USACE-Project Manager of any changes in personnel from that specified in the work plan.

2. Soil Borings and Monitoring Well Borings Soil borings and monitoring wells may be required to investigate the vertical and horizontal extent of site-specific contaminants. Soil samples for chemical analysis may also be required from borings drilled for monitoring well installations, as directed in the Site-specific SOS. Guidance for field activities may be obtained from USACE EM 1110-1-4000 (Nov. 98): “Monitoring Well Design, Installation, and Documentation at Hazardous, Toxic, and Radioactive Waste Sites”. All borings for soil sampling and monitoring well installations shall be drilled and sampled according to requirements discussed in the following sections.

2.1. Utility Clearances and Permits. The Contractor shall be responsible for obtaining and coordinating all utility clearances and drilling/monitoring well permits. A copy of all monitoring well permits required by state or local regulations shall be included as an appendix in the final report. If it is necessary to move a boring in order to avoid utilities, the Contractor shall be responsible for relocating the boring to a suitable location that accomplishes the intent of the original location. The new location shall be as close as possible to the original location. Both locations shall be georeferenced in accordance with USACE EM1110-1-4000 (Nov. 98):

“Monitoring Well Design, Installation, and Documentation at Hazardous, Toxic, and Radioactive Waste Sites” and paragraph: 7.5 Spatial Data unless otherwise specified under the Site-specific SOS, and the coordinates shown on the boring log. The Contractor shall take all reasonable precautions to protect persons and property near the drill site.

2.2. Drilling Methods. All borings shall be drilled by a method of the Contractor’s choosing unless otherwise specified under the Site-specific SOS, with the exception of air rotary method which is not permitted unless there is concurrence from the USACE Project Manager and Project Geologist. The drilling method(s) shall be proposed by the Contractor and approved by the USACE-Project Geologist prior to use. The method(s) shall be discussed in the Contractor work plans. The drilling method must allow, or provisions must be made for, accurate determination of the depth to groundwater surface. If a well is to be installed in a boring, the boring shall be of sufficient diameter to permit at least two inches of annular space between the boring wall and the sides of the centered riser and screen. The boring diameter shall be of sufficient size to allow for the accurate placement of the screen, riser, centralizers, filter pack, bentonite, and grout. The Contractor’s drilling method shall maintain the integrity of the borehole (i.e. prevent collapse) during backfilling or well installation. No grease shall be used on drill pipe joints. The use of any lubricants shall be submitted for approval in the Contractor work plans and shall be noted on the boring logs. The Contractor shall provide documentation (brand name, chemical analysis of product composition, etc.) for all materials introduced into the boring during drilling, for approval prior to use.

2.3. Aquifer Protection. If other than the uppermost water yielding zone is penetrated during drilling, precautions shall be taken to prevent the downward (or upward) movement of any cross-contaminants. The drilling method and procedure to be employed shall be described in detail in the work plans for USACE- District review and approval prior to field deployment.

2.4. Decontamination. All sampling equipment shall be decontaminated according to the requirements stated in the UFP-QAPP. All drill pipe, drilling tools, bits, etc. shall be free of potentially contaminating materials (i.e. soil, grease, oil, paint, etc.) and shall be high-pressure hot water washed prior to use at each well boring. Drilling equipment that is used down hole or may potentially cross-contaminate samples, such as augers, auger center plugs, core barrels, clean out bits, down hole geophysical equipment, etc. shall be decontaminated between each boring location. The drill rig shall be high-pressure hot water washed prior to use at each site if the project consists of more than one site. The rig shall be free of leaks and debris, which could contaminate the holes (i.e. hydraulic fluid, oil, gas, loose paint, etc.).

2.5. Geotechnical Sample Requirements. During drilling of all borings, soil sampling shall be performed at regular intervals to allow for accurate logging of the soil lithology and to obtain material for geotechnical testing. Sampling may be performed using a split spoon sampler or thin wall (Shelby tube) sampler using the techniques given in ASTM D 1586 “Standard Test Method for Penetration Test and Split-Barrel Sampling of Soils” and ASTM D 1587 “Standard Practice for Thin-Walled Tube Geotechnical Sampling of Soils”, respectively. Other type samplers (California split tube, hollow stem auger continuous sampler, etc.) may also be used if included in the Contractor work plans for approval. All samplers used to collect samples for chemical analysis shall be stainless steel. Samples to be used only for logging and geotechnical testing may be taken with sampling devices that are not stainless steel.

2.5.1. Sampling Intervals. Unless otherwise indicated in the Site-specific SOS, soil samples for lithologic logging shall be collected continuously for the first ten feet and every five feet for the remaining depth of each boring. Material recovered from geotechnical sample intervals may also be utilized to meet the requirements for chemical sampling, i.e. a sample for geotechnical testing and a sample for chemical analysis may be taken from the same split spoon. Where the material quantity is insufficient to meet all needs, samples for chemical analysis shall be collected first.

2.5.2 Soil Classification and Testing. All soil samples shall be visually classified in the field using the Unified Soil Classification System (ASTM D 2488 “Standard Practice for Description and Identification of Soils”). In order to verify the field classifications and to obtain additional data on the composition of the subsurface materials, the Contractor shall retain samples for laboratory geotechnical testing. Refer to the Site-Specific SOS for specific sampling and testing requirements. This testing shall consist of Grain Size Distribution (ASTM D 421 “Standard Practice for Dry Preparation of Soil Samples for Particle-Size Analysis and Determination of Soil Constants” and 422 “Standard Test Method for Particle-Size Analysis of Soils”), Atterberg Limits (ASTM D 4318 “Standard Test Method for Liquid Limit, Plastic Limit, and

Plasticity Index of Soils”), and moisture content (ASTM D 2216 “Standard Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock”). If multiple borings are performed at a site, the Contractor shall attempt to select samples for geotechnical analysis that are representative of all materials on site.

2.6. Logs. All drill logs shall subscribe to the following requirements:

2.6.1. Logs shall be prepared in the field, as borings are drilled, by a qualified geologist or geotechnical engineer. The preparer shall sign each log.

2.6.2. All log entries shall be printed. Photo reproductions shall be clear and legible. Illegible or incomplete logs shall not be accepted. One legible copy of each field log shall be completed and sent to the USACE-District within five days of completion of each boring or as required in the Site-specific SOS.

The boring shall not be accepted by the USACE-District before the drilling logs are received and approved.

2.6.3. Borehole depth information shall be from direct measurements accurate to one-tenth of a foot.

2.6.4. Logs shall be prepared on the HTRW Drilling Log Form (ENG FORM 5056-R, or standard Drilling Log Form ENG FORM 1836). The Contractor may use their company drilling log form if the form is functionally similar to the HTRW Drilling Log Form provided and is approved by the USACE- Project Geologist.

2.6.5. All relevant information blanks in the log heading and log body shall be completed. If surveyed horizontal control is not available at the time of drilling, location sketches referenced by measured distances from prominent surface features, shall be shown on, or attached to the log. If vertical control is not available, the depth measurement shall be recorded as feet (meters) below ground (grade) surface. The surveyed coordinates and elevations shall be recorded on the final log.

2.6.6. Log scale shall be 1-inch = 1-foot, unless otherwise specified in the Site-specific SOS.

2.6.7. Each and every material type encountered shall be described in column c of the log form.

(Material types are to be logged directly from samples and indirectly interpolated using professional judgment, drill cuttings, drill action, etc., between sampling intervals.) If a split spoon is used, the log should include the blow counts or refusal as an indicator of rate of penetration.

2.6.8. Unconsolidated materials shall be described as outlined below and in the following sequence:

2.6.8.1. Descriptive USCS classification in accordance with ASTM D 2488;

2.6.8.2. Consistency of cohesive materials or apparent density of non-cohesive materials;

2.6.8.3. Moisture content assessment, e.g., moist, wet, saturated, etc.;

2.6.8.4. Color (e.g. Munsell Color System);

2.6.8.5. Other descriptive feature (bedding characteristics, organic materials, macrostructure of fine-grained soils e.g., root holes, fractures, etc.);

2.6.8.6. Depositional type (alluvium, till, loess, etc.,)

2.6.9. Rock materials shall be described in the sequence outlined below and in accordance with ASTM C 294 and other standard geologic nomenclature including:

2.6.9.1. Rock type, lithology;

2.6.9.2. Relative hardness, lithification, induration;

2.6.9.3. Density;

2.6.9.4. Texture, grain size, porosity, angularity, and grain cement;

2.6.9.5. Color;

2.6.9.6. Weathering;

2.6.9.7. Bedding, cross bedded, graded bedding;

2.6.9.8. Fractures, joints, bedding planes, and cavities, including any filling material and whether open or closed;

2.6.9.9. Rock Quality Designation (RQD);

2.6.9.10. Other descriptive features (fossils, pits, crystals, etc.).

2.6.10. Stratigraphic/lithologic changes shall be identified in column c by a solid horizontal line at the appropriate scale depth on the log, which corresponds to measured borehole depths at which changes occur, measured, and recorded to the nearest one-tenth of a foot. Gradational transitions, changes identified from cuttings or methods other than direct observation and measurement shall be identified by a horizontal dashed line at the appropriate scale depth based on the best judgment of the logger. All lines shall be drawn with a straight edge and not by free hand.

2.6.11. Logs shall clearly show in columns e and f, the depth intervals from which all samples are retained, complete with sample number.

2.6.12. Logs shall identify the depth at which water is first encountered, the depth to water at the completion of drilling and the stabilized depth to water. The absence of water in borings shall also be indicated.

Stabilized water level data shall include time allowed for levels to stabilize and amount of borehole collapse.

2.6.13. Logs shall show borehole and sample diameters and depths at which drilling or sampling methods or equipment change.

2.6.14. Logs shall show total depth of penetration and sampling. The bottom of the hole shall be clearly identified on the log with a double line across all columns at the bottom depth of drilling and with the notation “Bottom of Hole.”

2.6.15. Logs shall identify any drilling fluid losses including the depths, at which they occur, rate of loss and total volume lost.

2.6.16. Logs shall show drilling fluids used including, as appropriate:

2.6.16.1. Source and volume of make-up water;

2.6.16.2. Drill fluid additives by brand and product name, and mixture proportions; and

2.6.16.3. Type of filter for compressed air.

2.6.17. Logs shall show depths and types of any temporary casing used, casing diameter, material, date and time temporary casing landed, and casing disposition.

2.6.18. Logs shall identify any intervals of borehole instability.

2.6.19. Intervals of lost bedrock core shall be shown in column e. Intervals of intact soil sampling attempts shall also be shown in column e, including depths from which attempts were made and length of sample recovered from each attempt. Bedrock coring information shall be recorded in consecutively numbered runs in column h and shall include the following:

2.6.19.1. Start and stop time of each core run;

2.6.19.2. Depth to top and bottom of each core run;

2.6.19.3. Length of core recovered from each run;

2.6.19.4. Size and type of coring bit and barrel; and

2.6.19.5. Measured depth to the bottom of the hole after core is removed from each run.

2.6.20. Any special drilling or sampling problems shall be recorded on logs, including descriptions of problem resolutions.

2.6.21. Logs shall include all other information relevant to a particular investigation, including but not limited to;

2.6.21.1. Odors;

2.6.21.2. PID/FID measurements or other field screening or test results; and

2.6.21.3. Any observed evidence of contamination in samples, cuttings, or drilling fluids.

2.6.22. Copies of the field logs shall be included in the Draft Project Report and drafted boring logs shall be submitted in the Final Project Report unless specified otherwise in the Site-specific SOS.

2.7. Backfilling. All borings shall be backfilled with a bentonite-cement grout or a high-solids bentonite grout in accordance with the Site-specific SOS and state regulations. Grout backfill shall be placed consistent with paragraph 3.6 of this supplement. Tamped cuttings may be used to backfill the borehole only if specified in the Site-specific SOS. The borings shall be backfilled immediately after the sampling is completed unless saturated conditions have been encountered or a monitoring well is installed. In borings encountering saturated conditions, a 24-hour groundwater level shall be measured before backfilling. Borings left open overnight shall be covered to lessen the potential for injury to personnel and to minimize the potential for any surface drainage entering the boring.

2.8. Site Restoration. The site shall be restored to the condition prior to fieldwork that is acceptable to the owner/base/facility within 5 days of the completion of the site investigation. High visibility areas or high traffic areas shall be immediately restored upon completion of the site investigation. Drums (if used) shall be staged to a pre-designated drum staging area specified by the owner as part of this site restoration. The drum staging area shall be identified in the work plans. The drums shall be placed on wooden pallets for temporary storage. The USACE-District shall provide the final approval of the site restoration.

3. Well Design and Installation

The wells shall be constructed according to all applicable federal, state, and local requirements. If the specifications as set forth in the SOS do not meet regulatory guidance or requirements, contact the USACE- Project Manager and Project Geologist for resolution of differences. The Contractor is responsible for determining all applicable regulatory agency requirements and for obtaining all state and local well permits required for wells with the yields anticipated during development and sampling.

All well materials shall be high-pressure hot water washed immediately before installation and shall remain clean until installed in the boring or the material shall be cleaned again. Factory sealed well materials (screen and riser) do not require decontamination if the plastic wrap is intact, without holes or rips, and the materials are not removed until immediately before installation. The following specifications shall be followed except when site-specific requirements may be different where noted in the Site-specific SOS. The Contractor shall provide documentation (brand name, sizes, etc.) for all well and seal materials that shall be used for well installation. This data shall be presented in the work plan. Where possible, all depths of materials will be directly measured with a weighted tape, recorded in the field logbook, and shown on the well construction diagram.

3.1. Well Riser. Well riser shall consist of poly-vinyl chloride (PVC) or stainless steel, unless stated otherwise in the Site-specific SOS. PVC pipe (if used) shall be new, threaded, flush joint, and as a minimum, conform to the requirements of ASTM F 480 “Standard Specification for Thermoplastic Well Casing Pipe and Couplings Made in standard Dimension Ratios, e.g. schedule 40 or schedule 80. It shall bear markings that shall identify the materials and shall carry the seal of the National Sanitation Foundation. Stainless steel pipe (if used) shall consist of new, flush-jointed and threaded, type 304, corrosion resistant steel, unless otherwise stated in the Site-specific SOS. Threaded flush-joint couplings with chemically inert O-rings, to form watertight unions, shall join riser sections. Adhesives or solvents shall not be used to join the casing sections. The use of Teflon tape on threaded joints is acceptable and shall be noted on the well construction log. No lead shot or lead wool is to be employed in producing seals at any point in the well.

3.2. Well Screen. The Contractor shall have the responsibility of selecting the screened area of the borehole so that the completed monitoring well provides data that meets the project data quality objectives. Well screen shall be constructed of the same size and strength material as the well riser, unless specified otherwise in the Site-specific SOS. The screen material shall be non-contaminating, non-clogging design. The Contractor shall review the SOS for Site-specific requirements. All screen sections shall be threaded, flush joint design.

Field slotted screen is not permitted. The slot size shall be determined by the Contractor based upon available subsurface data and designed to be compatible with aquifer and gravel pack material. For water table wells, normal, seasonal fluctuations in the water table elevation shall be taken into consideration when placing the well screen so that monitoring shall be possible throughout an average year. Normal fluctuations shall be determined through a review of local well records and available literature. Sediment traps (sumps, tailpipe) shall not be used below the screened portion in monitoring wells unless directed by the USACE-Project Geologist. The procedure to be used in the field for determining the screen placement shall be presented in the Contractor work plans.

3.3. Filter Pack. The annular space around the well screen shall be backfilled with clean, washed, well-rounded silica sand sized to perform as a filter between the formation material and the well screen. The grain size of the filter pack that is used shall be included in the Contractor work plans (with selection rationale) and shall be shown on the well construction log. A grain-size distribution curve for all filter pack material shall be submitted by the Contractor in the work plan and in the Final Project Report along with the well construction diagrams. Unless otherwise specified in the Site-specific SOS, the Contractor shall collect and test for grain size distribution a minimum of one representative sample of the filter pack material to assure compliance with the work plan. This sample shall be collected at the site. The filter pack material shall be tremied into place to avoid bridging and ensure a continuous filter pack throughout the screened interval of the well. The filter pack shall extend approximately 1-foot below, and 3 to 5 feet above the well screen. If the boring extends more than 1-foot below the bottom of the screen, the Contractor shall propose backfilling methods and materials in the Contractor work plan.

3.4. Well Plumbness and Alignment. All riser and screen shall be set round, plumb, and true to line.

This may require the use of centralizers. A 10-foot long section of pipe, ½ to ¾-inch less in diameter than the inner diameter of the well riser pipe (or screen), shall be run through the entire length of the well to check the alignment. The result of such test shall be recorded on the Daily Quality Control Reports and the installation diagram. If the pipe does not pass freely for the entire depth of the well, the Contractor shall replace or repair the well at no additional cost to the Government, if so directed by the Contracting Officer. The pipe section shall be decontaminated with high-pressure hot water washing prior to the test. Adequate precautions shall be taken to prevent cross-contamination of wells by changing the rope attached to the pipe or decontaminating the cable prior to each alignment test.

3.5. Bentonite Seal. A 3 to 5-foot thick bentonite seal shall be placed in the annular space above the well screen and filter pack sand. The seal shall be composed of commercially manufactured, solvent-free, sodium-bentonite pellets. “Coated” bentonite pellets shall not be used without prior approval from the USACE- Project Geologist. Bentonite pellets shall not exceed one-half inch diameter. A bentonite seal placed below the water table shall be allowed to hydrate eight hours or in accordance with manufacturer’s recommendation. If the bentonite seal is positioned above the water table, the bentonite shall be installed in 1-foot lifts with each hydrated a minimum of 30 minutes between lifts before proceeding. Clean, potable water shall be added to hydrate the bentonite. After the placement of the final lift, the bentonite seal shall be allowed to hydrate a minimum of an additional two hours or until the Contractor is confident the seal will function as designed before grouting begins.

The bentonite seal shall be placed immediately after installing the filter pack, unless the well is going to be developed prior to placement of the seals, in which case, the seal shall be placed immediately upon completion of development.

3.6. Annular Seal. Grout shall be placed by pumping through a side discharging tremie pipe with the lower end of the tremie pipe located within 3 feet of the top of the bentonite seal. Pumping shall continue until undiluted grout flows from the boring at the ground surface. The annular seal shall be placed within 48 hours, but no sooner than two hours after the final lift of the bentonite seal installation. Prior to surface completion, the grout annular seal shall be brought up to level of design.

3.6.1. Cement Grout. Cement grout shall be placed above the bentonite seal to the ground surface. The cement grout shall consist of a mixture of Portland cement (ASTM C 150) and water in the proportion of not more than 7 gallons of approved water per bag of cement (94 pounds). Additionally, 3 to 5 percent by weight of sodium bentonite powder shall be added unless prohibited by state or local regulations.

3.6.2. High-Solids Bentonite Grout. Commercially available high-solids bentonite grout may be substituted for cement grout with USACE- Project Geologist approval or specified in the Site-specific SOS.

If approved or specified, the grout shall be mixed in accordance with the manufacturer’s instructions. The slurry shall consist of a mixture of bentonite and the manufacturer’s recommended volume of water to achieve an optimal seal. The slurry shall contain at least 20 – 30 percent solids by weight and have a density of at least 9.4 pounds/gallon. The slurry weight shall be tested periodically with a mud scale to assure proper mixing.

3.7. Protection of Well. At all times during the progress of the work, precautions shall be taken to prevent tampering with the well or the entrance of foreign material into it. Run-off shall be prevented from entering the well during construction. Upon completion of the well, a suitable vented or loose fitting cap shall be installed to prevent material from entering the well. A vent hole of 1/8-inch diameter shall be drilled into the cap. The well riser shall be surrounded by a larger diameter protective non-corrosive steel or aluminum casing rising 2 to 3 feet above ground level and set an equal distance below the ground surface into the cement grout backfill. The casing shall be installed in a manner that does not hinder access to the monitoring well for purposes of cap removal, taking samples, or water level measurements. The outside of all protective casings and bollards shall be painted a color specified by the USACE. Refer to Site-specific SOS for color requirements (the default color- blaze orange). The protective casing shall be provided with a locking cap and lock. The cap shall be designed to prevent water from entering the protective casing. All locks shall be brass (non-rusting) and keyed alike. Three (3) duplicate keys shall be provided to the USACE unless otherwise specified. A minimum 2 feet by 2 feet square by 4 inches thick concrete (cement, aggregate, water) pad, sloped away from the well, shall be constructed around the well casing with the top outer edge at the final ground level elevation. A weep hole of 1/8-inch diameter shall be drilled into the outer protective casing within three inches above the pad to permit drainage of fluids that may accumulate. Three 2-inch diameter or larger concrete filled steel posts shall be equally spaced around the well and cemented in place 2 to 3 feet below ground, outside the concrete pad. The posts shall be a minimum of 3 feet above ground. The ground immediately surrounding the top of the well pad shall be sloped away from the well.

3.7.1. Flush Finish Completion. Some wells may be required to be finished flush with the ground or pavement if they are in areas of heavy traffic. This requirement shall be stipulated in the Site-specific SOS or determined by the site owner. If this is required, the Contractor shall submit the proposed locations and flush mounted well designs in the Contractor work plan for approval. Flush finished wells shall also be equipped with a lock and shall be protected from the entry of surface fluids into the well. Protective posts shall not be required on flush-finished wells.

3.7.2. Cold Climate Completion. In climates with alternating freezing and thawing conditions, the well must be designed to minimize the potential for damage caused by frost heaving. The Contractor shall determine the frost heave potential and include damage minimizing surface completion design details, such as a gravel blanket in lieu of the concrete pad or constructing a joint separating the concrete pad from the protective casing, in the Contractor work plan.

3.8. Monitoring Well Installation Diagrams. Suitable diagrams detailing the as-built configuration of each monitoring well shall be prepared for inclusion in the Project Report. A qualified geologist/geotechnical engineer present during all drilling operations shall prepare the diagrams. A legible field copy of each well installation diagram shall be completed and sent to the USACE-Project Geologist within five days of completion of the well. The USACE-Project Geologist shall not accept the well before the drill logs and installation diagrams are received and approved. Information provided on all diagrams shall include, but not be limited to the following:

3.8.1. Project and site names, well number, and the total depth of completed well;

3.8.2. Depth of any grouting or sealing, and the amount of cement and/or bentonite used, and the total boring depth;

3.8.3. Depth, diameter, type of well casing, and location of any blank pipe installed in the well;

3.8.4. Static water level upon completion of the well and after well development;

3.8.5. Installation date or dates, and name of the driller and the geologist/geotechnical engineer installing the well. The preparer shall sign each installation diagram;

3.8.6. All pertinent construction details of monitoring wells, such as depth, volume and description of all backfill materials installed (such as gravel pack, bentonite, and grout); gradation of gravel pack; length, location, diameter, slot size, material (PVC, etc.), and manufacturer of well screen(s), position of centralizers, etc.;

3.8.7. Source and volume of water added during drilling and well installation;

3.8.8. Descriptions of surface completion, including protective steel casing, protective pipes, and concrete surface seal;

3.8.9. A description of any difficulties encountered during well installation; and

3.8.10. Surveyed coordinates and elevation of top of ground and top of well riser where groundwater is measured. A notch or mark on the casing where is measured should be noted. (Generally, a mark or notch should be made on the north side of the casing.)

3.9. Temporary Capping. Any well that is to be temporarily removed from service or left incomplete due to delay in construction shall be capped with a watertight cap and equipped with a “vandal proof” cover satisfying applicable state or local regulations or recommendations.

3.10. Identification of Wells. The Contractor shall securely affix a permanent corrosion resistant tag to the outer steel protective casing of each well, which clearly identifies the well number, depth, date of installation, the company accountable for installing the hole, and the top of riser measuring/point elevation.

The well shall also be clearly identified as a groundwater monitoring well, (or other type of well as applicable) either on the tag or by other means which must be approved by the USACE-Project Geologist. On flush finished wells, the tag shall be fixed to the inside of the cover. The outside shall be labeled as a monitoring well, with the well number clearly identified.

3.11. Contractor Responsibility for Monitoring Wells. It is the responsibility of the Contractor to properly plan, design, install, develop, and test monitoring wells so that they are suitable to produce representative groundwater samples in sufficient quantity and quality for geochemical testing. The Contractor shall ensure that the intentions of this SOS and best construction practices are carried out.

3.11.1. Well Replacement. If the Contractor, due to his inadequate design or construction, installs monitoring wells that are not suitable for their intended use or not in accordance with specifications, the Contracting Officer shall disapprove the well and direct the Contractor to repair or replace it at the Contracting Officer’s discretion. This work shall be done at no additional cost to the Government.

3.11.2. Abandoned Wells. If a monitoring well is disapproved by the USACE- COR or is abandoned by the Contractor for any reason, the well (or borehole) shall be abandoned in accordance with paragraph: 6.0 Well Abandonment. Such work shall be done at no additional cost to the Government.

3.12. Well Development.

3.12.1. Procedures. Within one week after each well has been constructed, but no sooner than 48 hours after grouting is completed, the Contractor shall direct a program for the development of the well without the use of dispersing agents, acids, or explosives. The Contractor has the option of developing the well prior to placing the annular seal providing borehole stability can be maintained throughout this process and seal placement activities. This should be considered if significant settlement of the filter pack during development is anticipated. The objectives of well development are to: (a) assure that groundwater enters the well screen freely, thus yielding a representative groundwater sample and an accurate water level measurement, b) remove 3 to 5 times the well volume and volume introduced or lost during drilling and well installation, c) remove very fine-grained sediment in the filter pack and nearby formation so that groundwater samples are not highly turbid and so that silting of the well does not occur. Development shall consist of alternate cycles of mechanical surging and pumping or bailing until little or no sediment enters the well. If not specified in the Site-specific SOS, well development shall continue for a minimum of two (2) hours.

Sediment that enters the well during this process shall be removed. At the end of that time, the well shall be continuously pumped using an electric submersible or pneumatic-drive, positive displacement bladder pump.

Temperature, pH, specific conductivity, and turbidity shall be monitored during pumping (one reading per well volume). Pumping shall continue until these parameters have stabilized (10 percent change for the other parameters between four consecutive readings) and the water is clear and free of fines. If these parameters have not stabilized after four (4) hours of continuous pumping, then the USACE-Project Geologist shall be contacted for further direction. In an event that three consecutive readings below 50 NTUs cannot be achieved, the USACE-Project Geologist should be contacted immediately for further instruction.

If the addition of water is required to facilitate surging and pumping/bailing only formation water from that well shall be used. If this is not practical due to tightness of the formation then only bailing shall be done. In all cases, the utmost care shall be taken not to collapse well screens during development activities and at least three (3) times the water introduced or lost during drilling shall be removed from each well. The Contractor shall collect approximately one liter of the last water withdrawn from the well during development in a clear glass jar, label and immediately photograph it with a 35 mm or digital color photo, and submit the photo as part of the well development form or appropriate project report. The photograph shall be a suitably back-lit, close-up that shows the clarity of the water. Fines remaining in the water shall not be allowed to settle out prior to taking the photograph. The depth of any sediment that collects in the bottom of the jar after the sample is allowed to settle shall be noted on the Well Development Form. The nephelometric turbidity of the water shall be determined in accordance with ASTM D-1889 “Standard Test Method for Turbidity of Water” and shown on the final Well Development Form. Part of well development should be the washing of the entire well cap and interior of the well casing above the water table using only water from that well. The result of this operation should be a well casing free of extraneous materials (grout, bentonite, sand, etc.). This washing should be conducted during development not after development is completed. This washing should not be performed where free phase contaminants (i.e. petroleum products) are present.

3.12.2. Well Development Records. A legible well development form shall be prepared and completed for each monitoring well installed. The geologist/geotechnical engineer present during the well development operations shall prepare the form. A copy of the well development records, complete with original photos, shall be submitted to the USACE- Project Geologist within five (5) days of completion of well development activities. A sample form shall be submitted in the Contractor work plan. Copies of the completed well development records shall be included in the Draft Project Report and Final Project Report. Information provided on the well development record shall include, but not be limited to the following:

3.12.2.1. Name of project and site, well identification number, and date(s).

3.12.2.2. Date, time, and elevation of the static water level and bottom of well before development.

3.12.2.3. Method used for development, to include equipment, size, type and make of bailer and/or pump used during development.

3.12.2.4. Time spent developing the well by each method, to include the typical pumping rate used in development.

3.12.2.5. Volume and physical character of water removed, to include changes during development in clarity, color, particulates, and odor.

3.12.2.6. Volume and source of any water added to the well, and chemical analysis of the added water.

3.12.2.7. Volume and physical character of sediment removed, to include changes during development in color and odor.

3.12.2.8. Clarity of water before, during, and after development, including a backlit photo, and depth of any sediment which settles to the bottom of the jar containing the last one liter of water withdrawn from the well during development.

3.12.2.9. Total depth of well and the static water level immediately after, and no sooner than the following day after development.

3.12.2.10. Readings of pH, specific conductance, temperature, and turbidity taken before, during, and after development.

3.12.2.11. Name(s) and job title of individual(s) developing well.

3.12.2.12. Name and/or description of the disposal facility/area for the waters removed during development.

3.12.2.13. Photograph.

3.13. In-situ Permeability Testing (Slug Testing). Slug tests shall be performed for all new wells at each site only if specified in Site-specific SOS. After development and sampling of monitoring wells, the Contractor shall determine for each new well at each site the in-situ permeability of the screened formation using an appropriate method. The Contractor shall propose the methods expected to be used and references for those methods in the Contractor work plans. No water or other liquid may be introduced into the well. Both rising and falling head slug tests shall be performed, however, only the rising head portion of slug tests shall be analyzed in a well screened partially in the unsaturated zone. All instrumentation and materials placed into the well shall be decontaminated according to the requirements given for sampling equipment. If for any reason in-situ tests cannot be completed at any well, the Contractor shall contact the USACE Project Manager and Project Geologist, immediately for instructions.

3.14. Water Source. Water for drilling, decontamination, and other necessary field activities shall be arranged by the Contractor and approved by the USACE- Project Geologist. Chlorine-free water shall be used if a suitable source is available. The Contractor shall be responsible for collecting and transporting all water to the drilling areas for required uses. The Contractor shall sample the water at each source and test it for the same parameters specified for groundwater samples under the Site-specific SOS. In addition, a sample shall be obtained at the site from the delivery/transport vehicle and tested for the same parameters as the source sample.

This information and documentation of the source of the water (i.e. fire hydrant location, etc.) which was used and any impact it may have on any of the analytical results performed under this SOS shall be included in both the Draft and Final Project reports. The Contractor shall be responsible for providing any deionized water required to perform this work.

4. Sampling Techniques-Equipment and Methods

4.1. Soil Sampling. The number and type of samples for chemical analysis is specified in the Site-specific SOS. The sampling procedures and analytical methods are specified in the Site-specific SOS and the General Chemistry Supplement to the SOS.

Sampling for chemical analysis shall be performed using a stainless steel split spoon sampler, or similar sampling device. Alternate sampling methods may be proposed for approval by the USACE-Project Geologist in the Contractor work plans. Soil grab samples for volatile organic compounds (VOCs) or semi-volatile compounds (SVOCs) analyses shall be obtained by sampling the material retrieved in the split spoon. The portion of the split spoon sample that represents slough shall not be sampled. Sampling shall be done immediately upon opening the split spoon and shall be done as soon as possible once the split spoon sample is taken from the boring. When collecting samples with a hand auger, the VOC and SVOC samples shall be collected immediately upon retrieval of the sample at the surface. The Contractor is responsible to recover adequate soil volume for all analytical requirements. If the sample volume of the first sample is not adequate, another sample shall be attempted from immediately below the previous sample or from the same depth in a boring drilled immediately adjacent to the boring in which the sample failed. This shall be done at no additional cost to the Government. The Contractor shall include in the work plans methods to be used to recover additional samples that are consistent with the project data quality objectives. Shallow soil samples for chemical analysis may be obtained with a stainless steel hand auger or a similar device if approved by the USACE- Project Geologist in the Contractor work plans.

Homogenizing (mixing) of soil samples shall be performed in a stainless steel bowl using stainless steel stirring devices that have been decontaminated prior to each homogenizing procedure. Samples for VOCs or SVOCs shall not be homogenized unless specified in the Site-specific SOS. Alternative sampling methods shall be specified in the Site-specific SOS. Sampling equipment, sampling methods, and decontamination procedures shall be clearly indicated in the Contractor work plans.

4.2. Headspace Screening Method. If volatile organic compound contamination is expected, the Contractor shall screen all soil samples collected above the water table for volatile organic compounds in the field at the time of sample collection. Field screening shall utilize either an organic vapor analyzer equipped with a photo- ionization detector (PID) or a flame-ionization detector (FID). If a high humidity condition exists during the time period when field activity is to be performed, the FID is recommended since a PID is not reliable screening instrument under these conditions. The ionization potential of the lamp for the PID shall be optimized for the contaminants of concern. The Contractor shall perform field screening in accordance with the following procedures unless alternate procedures are submitted and approved in the Contractor work plans.

4.2.1. Immediately upon opening the split spoon (or other sample retrieval device) and after collecting the volatile organic sample (if required), a representative portion of the sample shall be collected and placed in a clean, contaminant-free jar. (The sample may be placed in a new, clean, plastic sandwich bag inside a jar to minimize the number of new jars required. If the plastic bag method is utilized, readings shall be taken inside empty bags to ensure no external contamination is being introduced.)

4.2.2. If the volume of sample recovered is insufficient for all analytical requirements, then the material used in the headspace readings could be utilized for any non-volatile sampling requirements (i.e. the headspace material could be used to fulfill the geotechnical requirements). NOTE: A headspace reading is not required from the additional sample that was retrieved immediately below the initial attempt due to insufficient sample volume.

4.2.3. Seal each jar with at least one continuous sheet of aluminum foil, using the jar lid to secure the foil.

4.2.4. Vigorously agitate the sample jar for at least fifteen seconds and then allow a minimum of ten minutes (or as the environmental conditions dictate) for the sample adequately to volatilize.

4.2.5. During cold weather, the samples shall be warmed to near room temperature prior to taking the headspace measurement.

4.2.6. Re-shake the jar and then remove the jar lid. Quickly insert the vapor sampling probe through the aluminum foil and record the maximum meter response (which should be within the first two to five seconds). Erratic responses should be evaluated in terms of high organic vapor concentrations or conditions of elevated headspace moisture.

4.2.7. Record headspace screening data on the boring log and any other appropriate documentation (e.g.

sample transmittals, field notebooks, etc.) as appropriate.

4.2.8. The screening instrument shall be calibrated according to the appropriate standard span gas and shall be calibrated a minimum of twice daily and before use after a long shut down period (i.e. lunch breaks, equipment breakdowns, weather caused breaks, etc.).

4.2.9. If sample jars are to be re-used in the field, jars must be cleaned according to field decontamination procedures for cleaning of sampling equipment. In addition, headspace readings must be taken to ensure no residual organic vapors exist in the cleaned sample jars.

4.2.10. Any deviation(s) from the approved procedures must be noted on the drill logs and the Daily Quality Control Report (DQCR), with the basis for the deviation(s) stated.

4.3. Low-Stress Groundwater Sampling. The primary objective of low-stress purging and sampling is to collect consistently representative groundwater samples without altering water chemistry. Low-stress purging and sampling techniques help to reduce high turbidity levels that may adversely affect sample quality, which commonly occurs with conventional techniques that use bailers or high-speed pumps. The Contractor shall provide all purging and sampling details, including equipment specifications, in the work plan. After development, all wells shall be allowed to stabilize for a minimum of two (2) weeks prior to sampling. For all wells, the Contractor shall determine (measure and record) depth to water and the total well depth using an electronic water level probe to determine the water volume to be purged. Prior to purging, determine the presence of Non-Aqueous Phase Liquids (NAPLs) at the top and bottom of the water column. If NAPLs are present, contact the USACE- Project Manager and USACE Project Chemist for further instructions. Note: when turbidity is a concern and DNAPLs are not suspected, do not measure the depth of the well prior to purging and sampling.

Calculate well volume using the as-build depth and measure the actual well depth upon completion of sampling activities. Alternative requirements for low-stress groundwater sampling procedures will be specified in the Site-specific SOS and the General Chemistry Supplement to the SOS.

4.3.1. Well Purging Procedure. A well must be purged with a pump prior to sampling to assure that true formation water is sampled instead of stagnant casing water. Suitable pumps for low-flow (minimal drawdown) purging and sampling include bladder pumps, positive displacement pumps, peristaltic pumps, electrical submersible pumps, and gas driven pumps. Bladder pumps and other positive displacement pumps are preferred by the USACE when VOCs are to be sampled.

Well purging devices (bladders, pumps, bailers, and tubing) should be constructed of stainless steel, Teflon®, and other inert materials to reduce the chance of these materials altering the groundwater in areas were concentrations of the site contaminants are expected near detection limits. Teflon® tubing is preferred for sampling VOCs, but polyethylene tubing is acceptable for single use provided if it is demonstrated not to contribute contaminants to the samples.