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Sampling and Analysis Plan - Addendum Specific to Field Sampling Plan for Delivery Order TO42
Section 5 - Investigation-Derived Waste Handling
IDW may include soil cuttings, drilling fluids, purged groundwater, well development water, decontamination fluids (water and other fluids), and disposable PPE. The drilling contractor will be responsible for bringing and/or constructing decontamination areas at the site sufficient for all drilling, as well as containing and managing produced solids and fluids. The air rotary drilling method will produce a significant volume of drill cuttings and groundwater. Past experience shows that managing the drill cutting is an expensive and time-consuming task. Parsons will evaluate two management techniques for this delivery order: a lined basin storage basin or portable temporary storage containers.
Pending regulatory approval, Parsons and CSSA plan to construct lined settling basins for retention of all drill cuttings and mud. The utilization of retention ponds will reduce or eliminate delays and costs associated with settling and disposing of drill cuttings on a case-by-case basis. IDW with a high solids content (drilling fluids) would be transported and discharged to a settling basin. IDW with a low solids content (well development water) will be transported to the CSSA GAC treatment plant for eventual treatment and discharge to Outfall 002. These options are being further evaluated, and a detailed plan will be provided as a separate deliverable at a later date. This settling basin alternative requires significantly less confirmation sampling and downtime associated with laboratory analysis and approval. However, significant engineering costs, a background evaluation of selected sites, costs associated with any permitting requirements, and issues with eventual pond closure, are factors to be considered.
At this time, Parsons is proposing to utilize a single settling basin located near the TPDES-permitted 002 outfall in the central portion of the post. An infiltration basin for the controlled release of uncontaminated water back to the environment will accompany the settling basin. The proposed site is located within the inner cantonment area at SWMU B-10.
CSSA proposes to utilize a lined settling basin for containment and will have bermed sides with sufficient freeboard to prevent stormwater run-on and designed to contain precipitation from storm events. The settling basin would use the clay-rich soil backfilled with SWMU B-10 as an underlying layer to a 60 mil High Density Polyethylene (HDPE) flexible membrane liner. The underlying layer will contain at least 1 foot of compacted clay-rich soil material along the sides and bottom of the basin intended to achieve the lowest permeability practical given the properties of the imported materials. The 60 mil HDPE liner would overlay the compacted clay soils. An access ramp will also be constructed for the offloading of liquid and solid media. Fencing will surround the settling basin to minimize potential exposure to wildlife and livestock.
All generated drilling materials will be taken to the basin via vacuum truck or other applicable transportation methods. The bulk of the material will be transported by vacuum truck as the drilling fluids are produced by the drilling subcontractor. Multiple transportable 20 to 30-yard roll-off boxes will also be placed at each well to contain media to allow for proper characterization. Wells, which may generate �contaminated� media, are MW16-CC, MW13-LGR, MW14-LGR, MW1-BS, MW1-CC, and MW2-CC. During installation of these wells IDW will be collected and sampled before placement into the settling basin. If analytical results indicate that the IDW is contaminated, it will be transported to the TPDES Outfall 002 treatment system where the liquid fraction will be treated and discharged in accordance with permit requirement. If however, analytical results indicate that the generated IDW is found not to be contaminated, the material will be transported and managed with the settling basin.
Periodically, sampling of the drilling materials within the basin will occur in order to identify appropriate management methods for the contained materials. The liquid fraction, which has analytical results greater than TRRP Tier 1 PCLs for CSSA�s COCs, would be routed through the GAC unit at CSSA�s Outfall 002. The solid fraction with analytical results above TRRP Tier 1 PCLs for CSSA�s COCs would be managed in an appropriate off-site landfill. If analysis of the materials indicates that the COCs are below the health-based standards (i.e., TRRP Tier 1 PCLs) they would be discharged to the ground surface.
CSSA is authorized to treat and dispose of wastes by TPDES permit no. 03849. The permit allows for the discharge of treated effluent wastewater from two outfalls (001 and 002). For this discussion, only Outfall 002 is being considered for potential treatment of contaminated media. Permit limits associated with Outfall 002 include treatment and release of wastewater at a daily average rate of 30,000 gallons/day and a daily maximum of 60,000 gallons/day. The maximum capacity of the current GWTP is 28,800 gallons per day. Effluent characteristics specified by the TPDES permit indicate discharge limits for daily average of PCE and TCE at 36 ppb and a daily maximum at 77 ppb.
Periodically, sampling of the drilling materials within the basin will occur in order to identify appropriate management methods for the contained materials. Parsons anticipates sampling of the media held in the basin to occur after the turbidity of the liquid fraction is less than or equal to 50 nephelometric turbidity units (NTU), or at most on a monthly basis. The NTU standard will be checked on a weekly basis. When the media meets the 50 NTU standard it will be appropriate for introduction into the GWTP. The solid fraction held within the settling basin will be characterized and removed, if necessary, upon completion of the Phase II drilling efforts.
If the settling basin has been found to contain �contaminated media� the settling basin will become apart of TPDES permit no. 03849. The settling basin will be used for future investigation efforts anticipated for the facility. Upon completion of RFI activities, closure samples will be taken from underneath the former settling basin location and analyzed for COCs for determinations to be made regarding proper closure criteria as specified in TRRP. If however, no �contaminated media� was found to have been managed within the settling basin, no closure efforts are required and future use will not be limited to TPDES requirements.
5.2 - Temporary Storage Containers
To commence drilling operations before the settling basins are completed, it may be necessary to use the �traditional� IDW containment strategy developed during Phase I of the CSSA Monitoring Well Installation Program. The traditional alternative is to place multiple (up to 10 or more) transportable 20 to 30-yard water-proofed roll-off boxes at each well cluster to temporarily contain drilling fluids. Drill cutting are placed directly into the containers at the site to settle and decant solids from the drilling mud. This process may take days for a single roll-off to sufficiently settle, and becomes a capacity problem while drilling high production intervals. Once the solid fraction has sufficiently settled, the liquid fraction of a roll-off container can be characterized for Short List VOCs (Table 4) to determine if the water will meet surface discharge requirements (less than MCLs). The liquid fraction of each roll-off is sampled to make the discharge determination. One issue with the liquid fraction analysis is that the presence of residual surfactants from drilling foam will foul an analytical gas chromatograph (GC) at elevated concentrations. A good field test for determining whether analysis on the liquid fraction is feasible is to mix one part roll-off water with nine parts deionized water in a clean unpreserved glass jar. Upon agitation of this field sample, if foaming action is observed within the sample, the roll-off requires more time to settle. Table 2 estimates the number VOC water screening samples that may be required in association with IDW activities.
Once a roll-off container is sampled, the determination to discharge water is based on the analytical results being less than the MCL (or Tier 1 PCL) for a particular compound. The determination of releasing uncontaminated groundwater is made in conjunction (and permission) of the CSSA environmental officer. Discharges to the surface are made to areas that do not have the potential for draining off-post. The roll-off may then be reused to store drilling fluids. Once the roll-off has accumulated approximately 50 percent solids, the container should not be used to store additional fluids until the solid fraction can be characterized and removed from the roll-off.
Any remaining mud/solids should be sampled for Short List VOCs (Table 4) for characterization. Solids with VOC concentrations less than the method detection limit (MDL) can be transported and disposed onsite as fill material. Detectable concentrations of VOCs will require offsite landfilling. Once the container is emptied, it may be re-lined and reused for storage. Table 2 estimates the number VOC mud/solids screening samples that may be required in association with IDW activities.
Additional roll-off boxes (covered, lined, and leak-proof) will be placed near the water treatment plant for processing of well development groundwater through a GAC unit. Contaminated groundwater (VOCs>MCL) produced during well development will be transported by the drilling contractor to these roll-off containers via vacuum truck for eventual treatment and discharge to permitted Outfall 002.
This process can be costly with respect to the culmination of both analytical costs and delays in drilling related to storage capacity problems. However, this will be the primary method of IDW handling until the lined basin method is approved and constructed.
5.3 - Granular Activated Carbon at Outfall 002
During this project, Parsons will maintain and operate the CSSA GAC unit located at Outfall 002. The operation and discharge limits are governed by the CSSA TPDES permit (Volume 6-2, NPDES). The purpose of the GAC unit is to treat small quantities of contaminated groundwater generated during investigative activities, and properly discharge it to the permitted outfall. The average outfall flow rate is permitted at 30,000 gallons per day, which is approximately 20.8 gallons per minute (gpm) over a 24-hour period.
In general, the GAC unit is comprised of a small centrifugal pump, cartridge-type pre-filters, two 200-pound GAC canisters, and meters that monitor the discharge. Water to be treated may be introduced into the system via a 500-gallon tank located within the building, or be pumped in from external rental tanks (or roll-off boxes) outside the building. The system can be operated in either a series or parallel configuration. The system is sized to match the daily average flow of 30,000 gallons per day. Each carbon canister is rated for a flowrate of 10 gpm, meaning the system can effectively treat contaminated groundwater at 20 gpm in a parallel configuration, or 10 gpm in a series configuration. Appendix E provides a generalized schematic and operational information for the GAC.
Parsons will be responsible for daily operation and maintenance of the GAC unit. It is imperative that the GAC unit be operated and monitored by those requirements set forth in the TPDES permit. Those operating the unit should familiarize themselves with its requirements. In general, the logsheet must be completed for each treatment operation. The TPDES permit requires that the discharge volume, average flow, instantaneous flow, and pH be monitored for each discharge event. The discharge volume and instantaneous flow can be recorded from the integral flowmeter. Likewise, the instantaneous pH measurement can be recorded from its dedicated meter. Total discharge is measured by recording the flow totalizer measurements before and after treatment. The instantaneous flow readout should be used to control the flow so the discharge rate does not exceed the engineered capacity (10 gpm in series or 20 gpm in parallel). Series operation is the preferred configuration because it allows the groundwater greater contact time with the activated carbon. However, during periods of peak treatment it may become necessary to operate in parallel to keep up with drilling production.
Filters should be checked regularly, and the pressure gauge monitored often for indications that the filters are becoming fouled. Both 1 micron and 5 micron filters are used to prevent suspended sediments from fouling the carbon canisters. In series, a 5 micron filter in filter chamber �A� should be followed by a 1 micron filter in chamber �B�. In parallel operation, both filter chambers �A� and �B� should be fitted with 1 micron filters. Suspended sediments will dramatically reduce the life of the GAC unit, and any means necessary should be employed to reduce the amount of solids entering the system. It is especially important that drilling fluids be given adequate time to settle suspended particles before attempting to process them through the GAC.
In accordance with the TPDES permit, samples from the GAC treatment will be collected twice during each week the GAC is operated. It is imperative this requirement be met. A monitoring week is defined as starting on midnight Sunday, and ending at midnight on the following Saturday. To ensure that the sampling requirements are attained, the following sampling schedule will be employed.
During the first treatment of the week, three samples will be obtained. At start-up, one sample will be obtained from sample port �A.� At the end of the treatment, one additional sample will be collected from sampling port �A� and one sample will be collected from sampling port �B.� The second pair of samples will be submitted for VOC analysis as given in Table 5, while the first sample is retained on ice in the sample refrigerator. If the GAC unit will be operated one or more times before the end of the week, one additional sample will be obtained at sample port �A� before the end of the treatment cycle, and the stored sample will be discarded. However, if the GAC unit is not operated at any other time that week, the first sample collected will be submitted for analysis. All samples will be analyzed with a 7-day turn-around-time.
The GAC unit log will be maintained at all times. In addition, maintenance records will be kept updated on the GAC log as well as the dry-erase board located within the GAC building. Filters also need to be inventoried on a bi-weekly basis. A copy of the GAC unit log will be provided to the CSSA Environmental Officer and faxed to the project manager every Friday so the monthly reports can be generated.