THE HARDAGE SUPERFUND SITE: A REMEDIAL DESIGN/REMEDIAL ACTION CASE STUDY
B. Costello and K. Wogsland
Nationwide Environmental Services, Inc., Denver, Colorado 80215, Phone: 303-232-2134, FAX: 303-232-1724
The Hardage Site operated as a permitted hazardous waste disposal facility from 1972 to 1980. Approximately 20 million gallons of wastes were shipped to the site. In 1984, EPA notified companies they were Potentially Responsible Parties for clean-up. NES provided project management services during RD/RA at Hardage. Remedy Design occurred between 1991 and 1993. Remedy components include 19 groundwater wells; 2,600-foot-long gravel-filled groundwater interceptor trench; 7,300-foot-deep Class-I non-hazardous injection well; removal of 3,820 drums; general site cleanup and debris removal; 80 gpm water treatment plant; and 14 acre RCRA cap over the source areas. Total construction cost was $20.7 million. The project was brought in on time and on budget with change orders less than 2 percent of the project total. Currently, NES is operating the remedy. The automated nature of the water treatment plant provides for 24-hour per day operation. Over 10 million gallons of water have been pumped, treated and discharged to the on-site, Class-I, non-hazardous injection well. Over 300,000 gallons of aqueous waste and NAPL have been safely removed and incinerated off-site.
Keywords: CERCLA, RD/RA, project management, cleanup
Site Location and Background Information
The Hardage Superfund Site is located approximately 35 miles south-southwest of Oklahoma City in McClain County, Oklahoma. The original site operated under an Oklahoma State disposal permit from 1972 until 1980 and received a variety of materials from industries in Oklahoma and Texas. Liquid materials were received primarily in bulk form or in drums. Bulk liquids typically were received in the Main Pit or North Pond. They were then transferred to temporary evaporation ponds in the West and East Pond mixing areas and were then mixed with soil and placed in the source areas. Drummed materials and sludges were also received at the site, and many of the drums were placed in the Barrel Mound and covered with site soils and soil mixed with waste. Some drums were placed on the west side of the Main Pit and were covered with soil.
In 1984, EPA notified companies that used the Hardage Site that they were Potentially Responsible Parties (PRPs) for cleanup at the site under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). In 1991, the PRPs formed a not-for-profit corporation, the Hardage Site Remedy Corp. (HSRC). The HSRC is responsible for implementing the design, construction, and long term operation and maintenance of the court-ordered remedy for the Hardage Site.
The remedy components to be constructed at the Hardage Site are described in Table 1. These components are as described in the HSC's Preliminary Design Report, completed in October 1989, except as modified by the August 9, 1990, order.
The modifications to the Preliminary Design Report consist of the following:
1. Liquid recovery wells were to be installed in the Main Pit as well as in the Barrel Mound.
2. The cap was to be modified to provide that the cap includes no less than two-and-one-half-feet of soil that has been compacted to a permeability equal to or less than 1 x 10-7 centimeters per second.
3. The vent system for removing vapors that gather in the gas collection layer of the cap was to be modified to provide for active removal of those gases by designing and operating the vent system so that the vents are the preferential pathway for the gases in the gas collection layer.
4. The wastewater treatment system was to be designed to treat all contaminants or pollutants which may be present in the influent in excess of applicable discharge limits and was to be operated in such a way as to avoid commingling liquids from different components (e.g., surface water shall not be mixed with water pumped from the trench prior to treatment) without EPA approval. However, this limitation on commingling did not preclude the commingling of liquids from the V-shaped interceptor trench, vertical liquid recovery wells in the Barrel Mound and Main Pit, and underdrains beneath the cap. Water from the southwest interceptor wells cannot be commingled with fluids from the groundwater interceptor trench system or other related components.
1993 Modifications to the Remedy
On August 31, 1993, as the design of the site-wide remedy was nearing completion, the court issued the Order Modifying Remedy Implementation: Mounds Liquids Recovery System and On Site Injection Well. The elements of the order were as follows:
1. The total number of recovery wells in the Barrel Mound and Main Pit was reduced to 16 from the original 68. This meant that in addition to the 14 existing wells, two new wells would be installed during remedy construction. Should operational experience indicate that the 16 wells are not sufficient for removal of pumpable liquids, the HSC parties were to advise the court and EPA as to the number and location of the additional wells needed.
2. A two- to three-foot layer of a viscous, tarry waste-sediment mixture was identified at the bottom of the Barrel Mound and Main Pit area. This "bottom mass" is not pumpable using traditional liquid pump technology, and the only available recovery method for removing the bottom mass from the Barrel Mound and Main Pit area would expose personnel to health and safety risks that are unnecessarily high relative to the marginal benefits of additional recovery. The court agreed with the HSRC that leaving this bottom mass in place was consistent with the objectives of the Remedy Order, and no further attempts should be made to remove it.
3. The court agreed with the HSRC that the remaining volume of recoverable liquids in the Barrel Mound and Main Pit area is less than initially estimated and that the initial MLRS demonstrated that the 16 recovery wells can effectively remove pumpable waste liquids and contaminated water from the Barrel Mound and Main Pit. This conclusion is based on operational field experience gained during operation of the initial Mounds Liquids Recovery System in 1992 and 1993.
4. The HSRC could, in its discretion, continue to operate the mounds liquids nonaqueous phase liquids (NAPL) separation facility and dispose of the water and NAPL separately, or it may bypass the NAPL-separation facility and dispose of all mounds liquids as NAPL. A cost analysis will determine if any cost savings will be realized by bypassing the separation facility and incinerating the extracted liquids volume at the higher NAPL price. Any mounds liquids which contain NAPL, whether separated or not, must be incinerated at a facility certified under the Toxic Substances Control Act to meet relevant destruction efficiency requirements.
5. The water treatment system effluent discharge options are to be modified to include, as the preferred option, discharge into a non-hazardous on-site Class I injection well. The design and operation of this on-site Class I injection well shall be in substantial compliance with all applicable or relevant and appropriate requirements identified in the HSRC's May 1993 ARAR Compliant Submittal.
6. Requirements for discharge of effluent from the water treatment system were modified to meet acceptable criteria for discharge to the on-site Class I injection well. Pre-injection conditioning of the effluent is permitted to protect the injection zone.
The court found that the remedy modifications proposed by the HSRC and adopted in the August 31, 1993, order are consistent with the National Contingency Plan and with the previous Orders of the Court respecting the Hardage Site Remedy.
Implementation of the remedy for the Hardage Site was managed by the Hardage Site Remedy Corp. (HSRC), a not-for-profit, Oklahoma corporation incorporated on July 17, 1991. The responsible parties delegated the implementation of the remedy to the HSRC by a Remedy Management and Administrative Services Contract. The HSRC is represented by five directors/officers, elected annually from the member companies. The HSRC has retained services companies or individuals to assist in the design phase of the remedy implementation:
7. Nationwide Environmental Services, Inc., Denver, Colorado, was retained as the Technical Issues Manager for the HSRC and has been named to the court as the HSRC's Project Coordinator. NES is responsible for day-to-day management of IT's and Canonie's activities, as well as operation and maintenance activities at the site, and for coordination of the HSRC technical activities.
8. IT Corporation (IT) was contracted by the HSC on May 15, 1991, to prepare detailed designs and specifications and to implement the initial removal of mounds liquids. The services contract with IT was fully assigned to the HSRC in 1992. The design plans were completed and submitted to the court in May 1993. IT was retained as the oversight engineer for construction of the remedy, and to provide remedy trouble-shooting during the 5-year warranty period.
9. Canonie Environmental Services Corporation (Canonie) of Englewood, Colorado, was contracted by the HSRC on October 12, 1993, to construct the remedy compliant with the detailed design and technical specifications (Remedy Design) submitted to the court, the Environmental Protection Agency (EPA), and the Oklahoma Department of Environmental Quality (ODEQ) on May 21, 1993.
10. McKinney, Stringer & Webster, P.C., Oklahoma City, Oklahoma, was retained as corporate counsel for remedy design and implementation issues. They are responsible for any necessary interface with the court and regulatory agencies regarding remedy design and implementation.
11. The HSRC retained a site supervisor who maintains an active presence at the site and is responsible for all site activities not controlled directly by Canonie.
Initial Mounds Liquids Recovery System (MLRS)
The Initial Mounds Liquids Recovery System (MLRS) was constructed in 1992 to extract pumpable liquids from the Barrel Mound and Main Pit for off-site disposal. The system was in operation between December 1992 and April 1993. The MLRS was initiated prior to the remainder of the remedy to provide source control on an accelerated schedule.
The MLRS consisted of 14 recovery wells in insulated heat enclosures; 2,500 linear feet of double-contained process pipelines; two stage, three phase liquid-liquid separation system; two 5,000-gallon fiberglass NAPL storage tanks; three 12,500-gallon fiberglass water storage tanks; truck loadout system with separate loadout for NAPL and water; and a vapor recovery unit for the storage tanks and separators, hazardous gas continuous monitoring system in process area, leak detection system for all recovery wells, programmable logic controller (PLC) for remote system monitoring and control, and a fire suppression system.
Summary of Operations
Full start-up of the system was implemented on December 10, 1992. Initial pumping operations were conducted during daylight hours only for the first three weeks to verify proper operation of system components. After this initial period, the MLRS operation was expanded to seven-days-a-week, 24 hrs per day. Pumping continued on a 24-hour basis through the end of March 1993 except for one week in March when pumping was conducted for only eight hrs per day. The only significant problem encountered during start-up was clogging of the well pumps. All other equipment operated properly.
A total of 21 aqueous and seven nonaqueous shipments of bulk liquids were destroyed by incineration during 1993. One aqueous and two nonaqueous shipments were made prior to full MLRS start-up in December 1992. All shipped materials were destroyed at the Rollins Environmental Services, Inc., Deer Park, Texas, facility, with the exception of 44 drums which were routed to the Aptus Inc. incinerator in Coffeyville, Kansas in 1992.
Production Rates and Volumes
The total volume of liquids pumped during MLRS operations through April 9, 1993, was approximately 160,000 gallons. The total volume consisted of 126,000 gallons of aqueous phase (78%) and 34,000 gallons (22%) of NAPL.
The majority of the volume recovered by the MLRS was produced in the first four weeks of production. After January 10, 1993, the daily production rate declined substantially and in March 1993 the average daily production was 331 gallons per day (0.23 gpm). Approximately 80% of the total volume recovered was produced from three Barrel Mound wells: RW-1, RW-2, and RW-6. Barrel Mound wells RW-3 and RW-5 produced 14% of the total, and the entire Barrel Mound recovery well system (RW-1 through RW-6) produced 95% of the total volume. Only 5% of the MLRS production was from the Main Pit recovery wells.
The observed behavior of the liquid production rate and the rapid liquid level decline clearly indicate that the upper five ft of the 11-foot thick saturated zone in the Barrel Mound has a higher specific yield (volume of liquid produced per volume of matrix) and permeability than the lower six ft. Production rates declined substantially when the upper layer was drained and it is anticipated that the removal of liquids from the lower six ft will continue at a slowly declining rate over a longer period.
The behavior of production rates and liquid levels from the Main Pit wells do not indicate similar stratified characteristics. The production from the Main Pit wells has remained low since the start of pumping and the liquid levels have declined slowly. This indicates that the Main Pit, including the drum area on the west side, will continue to produce low volumes of liquid (less than 0.1 gpm) for a longer period.
Initial estimates of the volume of in-place recoverable liquids in the Barrel Mound and Main Pit area, based on various assumptions regarding the extent and condition of drums, porosity, and specific yield, ranged from less than one million to greater than two million gallons. It is now estimated, based on the operating experience gained during initial MLRS work, that the total volume of pumpable liquids in the Barrel Mound and Main Pit area, prior to initial MLRS operations, is approximately 300,000 gallons.
NAPL/Aqueous Phase Production Ratios
Approximately 126,000 gallons of aqueous phase and 35,000 gallons of NAPL were produced during operation of the system. The overall production of NAPL was approximately 22% of the total volume produced; one gallon of NAPL was produced for every 3.5 gallons of aqueous phase. Initially, prior to January 1993, the production was mostly aqueous phase. NAPL production then rose to as high as 50% on a weekly basis but then declined. Throughout March 1993, the proportion of NAPL was 14%. All of the recovery wells produced NAPL and NAPL was observed in all of the piezometers.
It has not been possible to estimate the relative ratio of production of LNAPL (floater) to DNAPL (sinker) because the LNAPL tends to dissolve the DNAPL. This phenomenon was observed in the pilot test in January 1992. The resulting mixture is processed through the separation facilities as floater. The principal reason for this phenomenon is that the density difference between the LNAPL and DNAPL is less than 0.1 gm/cm3, with the density of the aqueous phase between the two. The LNAPL production appears to have been greater than the DNAPL production; however, it is not possible to determine the exact ratio.
Liquid Level Changes
The liquid levels in the recovery wells and piezometers continued to decline through operation of the system; however, the rate of decline decreased with time. During the MLRS operations, the saturated thickness in the Barrel Mound decreased from an initial average of 11 feet to approximately 5 feet. The Main Pit saturated thickness declined from an average of 16 feet to approximately 9 feet. The most recent rate of liquid level decrease indicates that it will take at least several years to lower the liquid levels in the Main Pit and Barrel Mound to near the bottom of the pumpable liquids.
Throughout the four month operating period, the MLRS equipment operated on a continuous basis with only a few relatively minor adjustments and changes. The most significant change to the system involved raising the recovery pump intakes approximately two to three ft off the bottom of each recovery well due to a two to three-ft thick layer of thick sludge-like material and sediment that had accumulated at the bottom of each well. The reciprocating recovery pumps are not capable of pumping this thick mixture of sludge-like material and sediment, in spite of efforts to develop this layer out of the wells. Raising the pumps was successful in alleviating additional clogging problems. In addition, the recovery well intake screens were clogged by the thick sludge-like material. This problem was resolved by removing the intake screens on some of the pumps.
In order to evaluate recovery of the thick sludge-like material, a rotary auger pump was installed in one well. Initially, the liquid from that well was placed in drums because of concerns about clogging of the pipelines. After the production of thick sludge-like material declined and less viscous liquids were produced, the auger pump was connected to the main pipeline and the less viscous liquid was processed normally through the system.
All of the process equipment including the two liquid-liquid separators performed as designed. At one point, the Teflon seals on the Veirsep® separator pressure regulator valves had deteriorated and were replaced by Viton®. The control system and PLC programming required only minor changes. Several pipeline leaks occurred, caused by mechanical failure, but were contained in the well vaults, detected, and repaired. All of the storage tanks and load-out equipment performed as designed, although the NAPL load-out pump did require some adjustment during operation because the pump tends to cavitate as the NAPL becomes more viscous. All of the instrumentation including the leak detection, area gas monitors, temperature sensors, and well-level/liquid-level sensors performed as designed.
Shutdown and Decommissioning
After mid-January 1993, the production flow rates declined substantially as a result of drawdown. Accordingly, the HSRC decided to shut down and decommission the MLRS in preparation for construction of other components of the remedy including the cap. The system shut down on April 9, 1993, at a point in time when the aqueous tanks were almost full, requiring off-site shipment.
Decommissioning was conducted during the period April 13 through May 1, 1993, and consisted of the following key activities:
Well Field: All recovery pumps were removed and cleaned with a hexane and citric acid-based wash. Liquid transfer lines were pressurized with compressed air to clear residual aqueous and nonaqueous-phase liquids (NAPL), and the inner (primary) lines were removed and stacked in the well field along the western side of the mounds. All well vaults were high pressure washed to remove gross residual contamination. Recovery well and piezometer casings were capped and sealed.
Storage Tanks: Liquids within each of the aqueous storage tanks were recycled to remove most residual nonaqueous floating phase. Nonaqueous liquids were consolidated in the nonaqueous storage tanks.
Phase Separation Process Area: Both the Monarch® and the Monosep Veirsep® separator systems were flushed, drained, and high-pressure washed to remove residual gross nonaqueous phase. Nonaqueous and aqueous liquid transfer and recycle diaphragm pumps were broken down and cleaned. All fixed-air instrumentation was disconnected and placed in storage. All process lines were pressurized with compressed air and drained.
Final Transport Loadout Operations: Final loadout included liquids accumulated during MLRS operations plus liquids collected during decommissioning high-pressure washing. Following loadout operations, the transport weigh scale and the control trailer were returned to their respective vendors.
Inspection of the well field pumps after removal revealed some degradation of the stainless steel bearing, probably caused by chlorine corrosion. Otherwise, the decommissioning did not reveal any significant equipment problems and the system components will be reused during permanent operations.
During the remedy construction, the remaining well field equipment was removed in order to allow the Barrel Mound preload to be placed. After the preload period, the well casings were extended and the cap was built. The pumps were then replaced for long-term operations.
Permanent Mounds Liquids Recovery System (PLRS)
Minor modifications to the MLRS were performed to integrate it into the permanent remedy. One modification performed during January 1994 included the installation of the two new recovery wells. As a part of this work, two piezometers were abandoned. The two new recovery wells and the surface of the abandoned piezometers were temporarily sealed to isolate them for anticipated preload and cap construction activities in the area.
Soundings of the recovery wells conducted after the duration of the preload indicated that several of the recovery wells were affected or damaged during application of the preload to the Barrel Mound. Eight of the 16 recovery wells appeared to contain a very viscous, sludge-like material (bottom mass) of varying depths. This material was assumed to have been forced into the wells as a result of the preload overburden pressure. Of these eight wells, four to six were observed to have possible damage or blockage, restricting their future use in the PLRS.
To further define these conditions, a screw auger was used to redevelop the wells by augering out the bottom mass that had entered the well bore. The screw auger was also used to assess the plumbness of the well and to assess whether damage to the well casing had occurred restricting reinstallation of the PLRS recovery pumps. The screw auger consists of a steel-flight auger within a steel casing of approximately four-inches outside diameter (OD). The results of this effort are as follows:
Two recovery wells were cleared of the bottom mass and determined to be suitable for use in the PLRS.
Two recovery wells were cleared of the bottom mass but appeared to have been forced out of vertical alignment. However, it was determined that the shift from vertical would not prevent their use.
Four recovery wells were damaged or blocked. These wells were redeveloped to the depth of blockage.
Approximately 150 gallons of combined bottom mass and liquids were generated during the redevelopment activities and placed into four drums. These drums were stored in the drying shed for future processing through the PLRS and subsequent off-site incineration.
The four damaged recovery wells were replaced after completion of cap construction in December 1994. The old recovery wells were abandoned consistent with the procedures specified by the Remedy Design Specifications for mound well abandonment and sealed prior to cap construction. To support reinstallation of the four damaged wells, a 14-inch diameter, high density polyethylene (HDPE) pipe was installed immediately adjacent (to within five ft) to the abandoned well. This pipe is intended to serve as a "sleeve," protecting the various layers of the cap and allowing installation of the well after cap construction. At the two partially damaged recovery wells, sleeves were installed adjacent to them in the event that future shifting of the mounds causes the wells' plumbness to impede PLRS pumping operations. The reinstallation of the damaged recovery wells was completed in December consistent with the procedures specified by the Remedy Design Specifications for construction of mounds liquid recovery wells.
The HSRC evaluated whether the PLRS separation facility could be modified to operate at a lower cost than the MLRS separation facility. The proposed modifications to the system consist of converting the old automated operating system to a manual mode. Liquid levels will be monitored by an operator and the pumps will be controlled manually. All control of equipment and instruments by the programmable logic controller (PLC) will be eliminated and critical operational parameters will be monitored on local and remote indicator displays. Conceptual design modifications for the PLRS were completed in July. A meeting was conducted with EPA and their oversight contractor Fluor-Daniel in Dallas, Texas, on August 18, 1994.
Based on final evaluation of a "design/build" alternative and the cost associated with implementation of the redesigned system, the HSRC decided not to pursue modification of the system at this time. Instead, the MLRS was reinstalled as originally designed with one major exception: the Veirsep® separator along with the associated four transfer pumps and monitoring equipment were not reconnected. The system is operated manually through the PLC, rather than the automated control intended in the Remedy Design, to better control liquid flow through the process.
Groundwater Interceptor Trench (V-Trench)
The V-Trench was constructed to capture groundwater and NAPL, if any, migrating from the source areas for treatment and subsequent disposal. The V-Trench consists of a 3-foot wide and 60-foot deep gravel-filled trench that extends 2700 ft from the western edge of the site around the source areas to the eastern end of the site.
The final V-Trench Construction Work Plan was submitted in January 1994. Construction began on the western leg of the V-Trench simultaneous with the construction of the permanent diversion berm and the work platform. The V-Trench was constructed from January to July 1994 with the following specific components completed:
Excavation and backfilling of the slot-trench and associated work platform along the entire alignment
Installation of the V-Trench recovery wells and in-line piezometers
Construction of the three permanent water crossings
The V-Trench pumphouse foundations
The assembly of the pumphouses' superstructures
V-Trench well development
Construction of the V-Trench gathering system
Installation of underground piping, instrumentation, and electrical components.
To support V-Trench construction activities, groundwater was pumped from the trench to temporary storage tanks. After completion of the trench and recovery well installation, approximately 909,000 gallons of accumulated groundwater was treated by filtering the water to 200 parts per million or less total suspended solids followed by carbon filtration. The treated water was subsequently discharged back into the trench.
The following alterations to the trench were made as a result of conditions encountered during the construction process:
The Second Test trench was excavated and replaced due to potential siltation and water management impacts associated with the adjoining slot trench.
A "poorly cemented sandstone" zone was encountered along the trench alignment in the shallow valley area approximately between stations 5+85 and 6+25. Sloughing of the slot trench sidewalls in this area required the sides of the trench to be sloped back to prevent caving. The filter-gravel backfill and sand-backfill layer requirements in this area were modified to retard the migration of fines into the slot trench through this zone.
Installation of Southwest Recovery Wells
The Southwest Recovery Well component of the Southwest Recovery system was completed in September with the installation and development of the 19 recovery wells and the associated 26 piezometers. In addition to the wells and piezometers, the following components were completed:
Installation of surface well vaults for each of these wells
Foundation work for the Southwest Metering Houses
Superstructure assembly for the Southwest Recovery System Meter Houses
Utility piping for the Southwest Wells and piezometers
Mechanical and electrical work connecting the well gathering and treatment systems.
Water Treatment Plant Construction
The Water Treatment Plant (WTP) was constructed in 1994 and consists of separate treatment systems for groundwater extracted from the V-Trench and Southwest Wells. The V-Trench treatment system consists of a pretreatment stage to remove any NAPL that might accumulate in the V-Trench sumps for off-site disposal, settling to remove suspended solids from the water and addition of acid to lower the water's pH and to reduce metal hydroxide precipitation in subsequent stages. Treatment of organics is accomplished by air stripping followed by organics polishing using two carbon adsorption vessels. The effluent is then stored for final pH adjustment. The Southwest Wells treatment system consists of an influent storage tank to level the flow rate to the system and to filter suspended solids from the water followed by organics treatment using carbon adsorption units. Effluent from these two treatment systems is combined for final pH adjustment. Initially, addition of potassium chloride to 2% was done before final discharge to the Class-I non-hazardous injection well.
As a component of the Court Order Remedy, a composite cap was constructed to cover the source areas defined as the Barrel Mound, Main Pit, and Sludge Mound to prevent direct contact with the materials in these source areas and to inhibit the percolation of surface water into affected materials below the cap. The cap consists of a gas collection layer, 30-inch fine-grained soils layer, a drainage layer, and a 24-inch random soil layer vegetated with native grasses.
A toe drain was constructed along the north, west, and south of the Barrel Mound and Main Pit to collect lateral seepage of liquids. The installation included the placement of a perforated HDPE pipe collection system, a fiberglass reinforced polyethylene (FRP) collection sump and pump, geogrid, a gravel drainage layer, geotextile filter fabric, and cover soils.
Management of the toe drain system consisted of monitoring, pumping, and transferring accumulated liquid from the collection sump to storage tanks and subsequent off-site disposal. The accumulation of liquids in the toe drain was monitored weekly throughout 1994. During the first quarter of 1994, no liquids were removed from the toe drain sump. During the second, third, and fourth quarter 1994, approximately 12,000 and 10,000, and 2,500 gallons of liquids were removed from the toe drain sump, respectively. Initially, the liquids were stored in Baker tanks prior to off-site disposal. During the third quarter 1994, the liquids were transferred to the MLRS storage and separation systems in the drying shed. The liquids were separated, using the Monarch separator, into aqueous and NAPL phases and stored in the MLRS aqueous and NAPL tanks for off-site disposal.
In 1994, approximately 25,000 gallons of the accumulated toe drain liquids were processed and shipped off-site for incineration at the Rollins Environmental Services, Inc., Deerpark, Texas, facility.
Attic fill was placed in the Sludge Mound, Main Pit, and Barrel Mound areas to design grades. The following is a general list of materials used as attic fill:
Drums from the drum compound and throughout the site including soils excavated from the drum compound area
The old silo located on the site
Spoils and sediment from the WFP closure and construction of the new retention ponds
Potentially affected soils from the site associated with the excavation of the V-Trench work platform
Spoils from the slot-trench excavation
Soils from the preload remaining in place after completion of the surcharge period (below the precover grades)
Excavated materials from the North Drum Area closure
Daily cover material obtained from site borrow sources
Drum cuttings from the well installation activities
Existing decontamination pad and associated soils
Sediments from the Southwest and East Retention Ponds decommissioning activities
Chipped/shredded pallets from the historic Drum Compounds
Drilling mud and cuttings from construction and installation of the injection well
Archived core samples from previous investigations.
The preload placed on the Barrel Mound was intended to promote settlement and to enhance the crushing of buried drums by providing an overburden pressure greater than the final cap. Preload construction began in January 1994 with the establishment of the initial settlement monitoring survey grid. Placement and compaction of the preload was completed in March. An as-built and settlement monitoring survey grid was established. Settlement monitoring utilizing this survey grid was conducted weekly during the surcharge period. The surcharge period lasted two months and ended on May 5, 1994, after which the preload was removed to pre-cover grades.
During preload construction, liquid level monitoring was conducted and casing extensions were installed to the MLRS wells and piezometers according to the Remedy Design Specifications. The liquid levels of some of the wells and piezometers rose to elevations above the final cap design grade. Therefore, 2,700 gallons of liquids were pumped from wells and piezometers during Preleoad. The liquids were pumped directly to a tanker truck for shipment and incineration at Rollins Environmental Services, Inc. incinerator in Deerpark, Texas. No apparent settlement of the Preload was documented resulting from the liquid removal, therefore, no additional pumping of the Barrel Mound liquids was deemed necessary.
Active Gas Venting (AGV) System
The AGV system is designed to maintain a slight vacuum on the active gas vents for removal of off-gasses which may collect under the composite cap. The system consists of the gas collection layers, active gas vents and all piping, fittings, and equipment to deliver the collected gases to the Thermal Oxidation Unit (TOU) for destruction.
The granular gas collection layer of the AGV system was installed. Geogrid reinforcement was installed within the collection layer over those areas where drums had been placed. The AGV building was constructed in 1994.
The barrier layer of the cap consists of a 30-inch clay layer compacted to a permeability of less than 1x10-7 cm/sec. The clay layer was placed on a geotextile fabric and overlain by a 40 mil VLDP liner and a synthetic drainage layer.
A test fill approximately 100 by 50 ft was constructed adjacent to the western entrance to the site to test the proposed clay source for barrier layer construction. A sealed double ring infiltrometer (SDRI) was installed, and a SDRI permability test was performed. The relationship between compacted moisture-density and permeability for clay was established at the test fill. The results indicated that the proposed clay source was acceptable for cap construction.
Based on preliminary results from the test fill, the contractor proceeded with placement of the clay component of the cap barrier layer in July 1994. Placement of the geomembrane component of the barrier layer began in August 1994. Construction of the barrier layer was complete in the fourth quarter 1994.
The placement of geomembrane was interrupted in late October 1994 when high winds damaged approximately five acres of installed liner. Salvageable geomembrane was supplemented with new liner to repair the damaged area. Ten mounds liquid recovery wells, three piezometers, and three AGV risers located within the damaged area were visually inspected and/or sounded to determine if they were damaged. The casings of four of the ten recovery wells and two of the piezometers were damaged near the surface and were repaired. One recovery well was damaged approximately four ft below the finished cap grades and was repaired during PLRS installation. Two of the three AGV risers were pulled and replaced.
Construction of the vegetative layer component of the Cap included topsoil placement, seeding, and erosion-matting installation. The work was completed during the fourth quarter 1994 except in the area of the PLRS construction. Fertilizer application and irrigation of the cap area were delayed until early spring to prevent premature germination of seed and to allow PLRS construction.
Cap Profile Redesign
A slope stability analysis of the cap vegetative layer was conducted because of concerns associated with a reevaluation of the cap profile utilizing an alternate computing method and different soil parameters for the vegetative layer than those assumed during design. The slope stability analysis indicated that the steeper slopes of the Sludge Mound and the western side of the Main Pit and Barrel Mound may experience "veneer" failure of the vegetative layer above the geomembrane liner.
The HSRC took the following actions to address the slope stability issues:
HSRC had an independent, third party review conducted of the stability analysis and cap profile. The third party, GeoSyntec Consultants of Huntington Beach, California, concurred that there was a stability issue with the existing cap profile on the steeper slopes of the Sludge Mound and the western side of the Main Pit and Barrel Mound. They recommended replacement of the existing geosynthetic components of the cap profile with a textured geomembrane liner and a geocomposite drainage layer.
The cap profile was modified on the western slopes of the Main Pit and Barrel Mound consistent with GeoSyntec's recommendation. The present cap profile's smooth geomembrane liner was replaced with a textured geomembrane, and the geonet/geofabric drainage layer was replaced with a geocomposite drainage layer. The geocomposite drainage layer consists of a geonet drainage medium, factory-fused between two geofabric layers. Both substituted materials are consistent with those materials replaced and provide compliance of the profile with the stability requirements of the cap design.
Since the Sludge Mound geomembrane liner and geonet/geofabric drainage layer was already installed, the predicted instability was addressed by the inclusion of a reinforcing geogrid placed directly on top of the geonet/geofabric drainage layer. The addition of the geogrid rendered the stability of the profile compliant with the performance criteria of the design.
A laboratory testing program was conducted to determine:
12. Shear strength characteristics of the proposed vegetative layer borrow soil to support the stability analysis of the cap design
13. The interlayer friction characteristics of the smooth geomembrane liner and the geonet/geofabric drainage layer to support the selection of the reinforcing geogrid and the confirmation of stability for the remaining cap areas.
Alluvial Monitoring System
A total of 20 wells were installed to monitor attenuation of constituents in alluvial groundwater during operation of the remedy. Seven of these wells were installed during February 1994; the remaining 13 wells already existed.
Hardage Injection Well No. 1
A 7,500 ft deep injection well was constructed to dispose treated groundwater from the Water Treatment Plant. Injection of treated groundwater to the Injection Well began on February 28, 1995.
During start-up and initial operation of the WTP and injection well, potassium chloride (KCl) was added to the WTP effluent prior to injection. This was done to maintain a concentration of 2% KCl by weight in the injection fluid. The KCl was added to diminish or prevent clay swelling in the injection formations. The cost of adding KCl to the WTP effluent represented a significant portion of the overall O&M costs at the site. Therefore, a testing and monitoring program was initiated in August 1995 to evaluate if the amount of KCl could be reduced or eliminated.
The program consisted of conducting an injection profile log, injecting WTP effluent containing 1% KCl, and monitoring for any changes in the injection pressure, injection rate, and injection volume. Hall plots were prepared and analyzed to determine whether the injectivity of the well changed as a result of the change in KCl concentration in the injection fluid. If monitoring data indicated no reduced injectivity as a direct result of the change in KCl concentration of the WTP effluent, the KCl addition would be eliminated.
The injection profile log was run on August 8, 1995, under the supervision of W.H. Elliott of Elliott Engineering Company. The objective of the profile was to determine the distribution of the injected water among the five sandstone injection zones before a reduction was made in the amount of KCl added to the injection water. The profile was run to establish a baseline which would provide guidance in deciding whether remedial work on the injection well was required, and if so, the type of remedial work. Results are reported in Table 2.
A comparison of the August 8, 1995, distribution with the original distribution obtained during installation of the Injection Well indicates that some damage occurred to the Lower Noble Olson and possibly to the Upper Noble Olson. The majority of the injection fluid was being injected into the Fortuna E3. Core testing performed during installation of the well indicated that little or no damage should have been expected from injection of fluid containing less than 2% KCl.
On August 17, 1995, the addition of KCl to the injection water was reduced from 2% to 1%. Review of the monitoring data with injection at 1% KCl showed that an increase in the injectivity index shown on the Hall plot may have occurred; however, if it did, it was not mathematically significant. Based on these initial results, injection of the WTP effluent containing 1% KCl was continued. After further review of the monitoring data in January 1996, it was determined that there was sufficient evidence to support the contention that the KCl addition could be discontinued without the well suffering a significant loss of injectivity. The KCl addition was discontinued on January 15, 1996.
The Hall plot at the end of eleven hrs of operation on January 28, 1996, indicated that the surface (pseudo) injectivity index of the well when injection began in February 1995 was 2.3 barrels per day/psi. At the end of January 1996, the (pseudo) injectivity index was one barrel per day/psi. The total loss of injectivity was now 55% of the original.
The Hall plot shows that injectivity was lost while KCl additions were at the 2% level, that the loss continued at the 1% KCl level, and that the loss continues at the 0% level. The injectivity loss has not accelerated since the reduction to 0% KCl. Most of the loss, 39% of the original injectivity, occurred during the first two hrs of injection. The high early loss and the continued, unaccelarated loss indicate that 2% KCl was insufficient to prevent damage to some of the formations. However, given the steady state production of WTP effluent at 15 gpm, the injection well is capable of meeting the injectivity for the foreseeable future.
Performance Evaluation of Site Groundwater Extraction Systems
During the second quarter of 1995, the HSRC contracted with S.S. Papadopulos & Associates (SSP&A), Rockville, Maryland, to update the previously developed site groundwater model with current data to determine if the recovery systems were operating as designed and that all contaminated groundwater was being captured.
The groundwater flow model described in SSP&A's initial report, dated October 1989, was modified using information developed in the Southwest Recovery Well investigations and was recalibrated to achieve agreement with data collected during the initial period of operation of the remedial system. The recalibrated model was then used to simulate the final steady-state conditions under operation of the remedial system. A combination of particle tracking and flow calculation were applied to the results of this simulation to determine capture zones of the V-Trench and the SWW. The general design and node spacing of the mesh were not altered. The model utilizes the generic USGS flow simulation code MODFLOW.
Variations in lithology and well performance indicated that adjustments in the model parameter distributions would be required to match observed conditions. Recalibration of the model was undertaken using data collected from February 27 through May 31, 1995. These data included flows to the V-Trench and drawdowns in response to operation of the Southwest Recovery Wells.
The model was recalibrated by simulating transient conditions for the period from February 28 to May 31, 1995. Based on information obtained during remedy design and implementation, two new hydraulic conductivity zones were defined to represent the terrace deposits and a short alluvial channel tributary to the North Criner Creek alluvium (and associated weathered bedrock).
The final equilibrium condition during operation of the remedial system was simulated, and particle tracking calculations were carried out to determine capture zones of the V-Trench and SWW system. The results show full capture of downgradient flow in Stratum III by these systems. The capture zone of the SWW system was verified by carrying out water balance calculations for a limited zone around the wells in Stratum III. The results of these calculations showed that discharge from the well system was closely balanced by the sum of flow from upgradient areas in Stratum III and local recharge in the vicinity of the wells. The sensitivity analysis showed that the uncertainties regarding the drain conductance of the V-Trench and the recharge rate on terrace deposits had no impact on the conclusions regarding full capture.
Water Treatment Plant Electrical Protection
During the third quarter 1996, the HSRC performed the following activities to minimize damage to the facility from electrical storms:
The 24-volt power supplies for all Local Integrated Processor (LIP) cabinets were grounded.
Each of the three 440-volt power supply poles were equipped with new lightning arresters that are designed to be more sensitive and quicker to respond.
An additional lightning arrester was installed just downstream of the main transformer.
All of the data transmission wiring was replaced with fiber optic cable. The old coaxial cable that was replaced was identified as having carried stray current from the lightning strikes between the LIPs and the WTP.
Transient voltage surge suppressers were added to the incoming power supply to the WTP.
The circuit breaker line guard that trips and shuts off the WTP during electrical problems was found to be damaged and was replaced.
On November 6, 1996, lightning struck in the vicinity of the site and a power surge came onto the site through the power lines. As designed, all damage was limited to the transient voltage surge suppressers.
A system-wide performance review for optimization of remedy components was performed by NES as part of the operation and maintenance program at the Site. NES collected and reviewed data pertaining to current site conditions and remedy component operations obtained during the first 12 months of remedy operation. These data indicate that under current site conditions, modification of certain components of the remedy would result in a more efficient cost effective operation and a reduction of air emissions from the site.
NES implemented the remedy optimization program during the third quarter 1996 following review with the Oklahoma Department of Environmental Quality (ODEQ) and the Environmental Protection Agency (EPA). These modifications will provide a more efficient operation of the remedy in accordance with the court order and all applicable regulations. The remedy optimization program included the following changes to the current configuration of remedy components:
Treatment of groundwater recovered by the V-Trench extraction system using the air stripper.
Treatment of the Active Gas Vent (AGV) off-gasses by carbon adsorption.
Discontinued operation of the TOU (leave in place for potential future change in conditions).
Since remedy start-up, performance monitoring of remedy components has been conducted to evaluate the effectiveness of the remedy and compliance with discharge limits during remedy operation as described in the Performance Monitoring Plan for Construction and Operations Hardage Superfund Site (PMP). The data were collected according to the procedures and protocols described in the Sampling and Analysis Plan for Construction and Operation of the Remedy Implementation, Hardage Superfund Site (SAP). The objectives of the performance monitoring are as follows:
Monitor performance and verify hydraulic capture of the V-Trench.
Monitor performance and verify hydraulic capture of the SWW.
Monitor operation and performance of the WTP and verify that effluent meets discharge requirements.
Monitor attenuation of constituents in the North Criner Creek alluvium.
Monitor water quality in North Criner Creek.
Monitor operation and performance of the Class I non-hazardous injection well.
The following sections present the results of the performance monitoring data collected during 1996.
V-Trench Recovery System
To demonstrate that the V-Trench is performing as intended, the following monitoring was performed: 1) water levels were monitored within and downgradient of the V-Trench to demonstrate hydraulic capture; 2) flow rates were monitored to document groundwater removal; 3) water samples from wells MW-21S and MW-21M were analyzed prior to start-up for VOCs, SVOCs, pesticides, PCBs, and inorganics then annually for VOCs; 4) water samples from the recovery wells were analyzed for VOCs, SVOCs, pesticides, PCBs, inorganics, and total suspended solids after six months O&M and every two yrs thereafter.
The performance standard states that "hydraulic containment shall be demonstrated if the water level in each piezometer located midway between a pair of trench sumps is at least one ft lower than the simultaneous water level in the nearest piezometer located directly down gradient."
V-Trench Recovery System Operation
The total cumulative volume of groundwater pumped from the V-Trench recovery system through December 1996 was 14,150,542 gallons.
The measured water level elevations show that the V-Trench is capturing affected groundwater migrating from the source areas. The data shows that the water levels in each in-trench piezometer located midway between a pair of trench sumps is at least one ft lower than the simultaneous water level in the nearest piezometer located directly downgradient and that the performance standard is consistently being met. Water level measurements collected in the trench indicate that pumping has achieved drawdowns of approximately 15- to 33- ft within the V-Trench.
Southwest Wells Recovery System
To demonstrate that the Southwest Wells Recovery System is performing as intended, the following monitoring was performed: 1) water levels are monitored along weand downgradient of the alignment to demonstrate hydraulic capture; 2) flow rates are monitored to document groundwater removal; 3) water samples from off-end monitoring wells SWMW-1 and SWMW-2 were for VOCs, SVOCs, pesticides, PCBs, and inorganics analyzed prior to start-up and than annually for VOCs; 4) water samples from recovery wells SWWR-01, SWWR-11, SWWR-17, and SWWR-19 were analyzed for VOCs during the first month of operation then every two yrs.
The performance standard for the SWW Recovery System states that "hydraulic containment shall be demonstrated if the water level in each piezometer located midway between the recovery wells is at least 0.1-ft lower than the simultaneous water level in the down gradient piezometers."
SWW Recovery System Operation
The total cumulative volume of groundwater pumped from the SWW recovery system since the system went on line was 2,663,932 gallons. The majority of the volume produced by the system continues to be recovered from SWWR-05.
The objective of the piezometer monitoring is to demonstrate a decrease in water levels due to pumping, that inward flow gradients are maintained, and that the performance criteria are being met. The water levels presented show that inward flow gradients are maintained at the northwest and central portions of the alignment. A small portion of the southeast end of the alignment shows an outward gradient.
The water levels in the northwest and central portions of the alignment are continuously at least 0.1-ft below the water level in the adjacent downgradient piezometer, and the performance standard has been continuously met and hydraulic containment is being achieved in those areas.
Water levels measured at in-line piezometers in a small area of the southwest end of the alignment controlled by recovery wells SWWR-16 and SWWR-17 have generally remained above the adjacent downgradient piezometer and the performance criteria has not been met. The HSRC revised the pumping regime for recovery wells SWWR-15, SWWR-16, and SWWR-17 to provide the maximum attainable drawdowns in SWWR-15, SWWR-16, and SWWR-17. Data collected from the piezometers since normal operations resumed in October 1996 indicate that an inward gradient was achieved for a period during December; however, the inward gradient could not be maintained consistently.
After review of these data, the HSRC initiated a two-week pump test of SWPZ-22i in January 1997. A pneumatic pump was installed in SWPZ-22i and pumped for two-weeks. Groundwater generated was treated in theWTP. Water levels were collected daily from adjacent piezometers. The data collected was evaluated and it was determined that an inward gradient can be achieved with additional recovery wells pumping from the alluvium in this area.
Water Treatment Plant (WTP)
The court order requires that the liquids from the V-Trench and SWW cannot be mixed before treatment; therefore, influents from the V-Trench and SWW recovery systems are treated in separate treatment systems. The influent constituent concentrations require treatment of organics to meet the toxicity characteristic leaching procedure (TCLP) concentrations in 40 CFR §261.24 and the ODEQ discharge limits (organic constituents only) for North Criner Creek. Where the organic discharge limits specified by the ODEQ are below the analytical minimum quantification levels, the discharge criterion is the minimum quantification level specified by the ODEQ for the specified analytical method.
SWW WTP and V-Trench WTP influent samples were collected monthly for the first six months of operation. Thereafter, samples were collected every six months for performance monitoring purposes. Additional influent samples were collected for operational purposes. Samples were collected according to the procedures described in the SAP and analyzed for VOCs.
The combined WTP effluent was tested twice each month for the first year of operation. According to design documents, the HSRC petitioned for a revised sampling schedule after the first year. Samples were analyzed for VOCs, SVOCs, pesticide/PCBs, metals, and herbicide analyses. All samples were collected according to the procedures described in the SAP.
The HSRC petitioned for a revised sampling schedule in 1996. The revised schedule was followed beginning first quarter 1997. The V-Trench WTP began processing groundwater extracted from the V-Trench recovery system on February 27, 1995. The Southwest WTP came on line on April 3, 1995.
North Criner Creek Alluvium
Water Quality Sampling
Twenty wells were sampled to monitor attenuation of constituents in alluvial groundwater. Prior to remedy start-up, during January and February 1995, the wells were sampled for VOCs, SVOCs, pesticide/PCBs, and metals/inorganics. After start-up, the wells to be sampled and the frequency at which sampling will be conducted were as follows:
Group 1: These wells will be sampled annually for VOCs only. If no VOCs are detected in two consecutive sampling rounds, the third round of samples will be analyzed for VOCs, SVOCs, pesticides/PCBs, and metals/inorganics. If no organic constituents are detected and inorganic and metal constituent concentrations are within the range of observed background concentrations, the well will be placed in Group 2.
Group 2: These wells will be sampled at 2.5 yrs, five yrs, and at five-yr intervals thereafter for VOCs only. If no VOCs are detected in two consecutive sampling rounds, the third round of samples will be analyzed for VOCs, SVOCs, pesticides/PCBs, and metals/inorganics. If no organic constituents are detected and inorganic and metal constituent concentrations are within the range of observed background concentrations, the well will be no longer be sampled.
Group 3: These wells are sampled annually for VOCs until all wells in the alluvium have been dropped from the Group 2 list. Group 3 wells will be analyzed for a full set of constituents together with the last of the wells from Group 2.
During first quarter 1996, Group 1 and 3 wells were sampled for VOCs per the PMP by NES personnel. Sampling conducted in 1995 and 1996 indicated that constituents were no longer detected on the west side of the creek. In general, constituents concentrations decrease downgradient, along with the number of constituents detected. The concentrations detected in the up-gradient portion of the plume indicated that total VOCs essentially stayed constant or increased.
Results of testing the groundwater from the North Criner Creek alluvium demonstrated that removal of up-gradient sources of groundwater constituents via on-site source control and the Southwest Wells recovery system coupled with natural attenuation were reducing constituent concentrations downgradient in the alluvial system.
North Criner Creek
Surface water quality in North Criner Creek was sampled annually at three stations during remedy implementation to assess any impact from the discharge of affected alluvial groundwater. Additional monthly sampling of North Criner Creek was initiated in January 1996 because portions of the land previously within the institutional controls boundary was returned to the land owner, thereby allowing access to the creek by the landowner. No VOCs were detected in any post-remedy implementation samples collected from North Criner Creek.
Hardage Injection Well No. 1
Injection of treated groundwater to the Class I non-hazardous injection well began on February 28, 1995. Since start-up of the remedy, 16,814,474 gallons of treated effluent have been injected into Hardage Injection Well No. 1. During operation, volume, injection pressure, annulus pressure, and injection rate for the Hardage injection well were monitored. The monitored data indicated that the injection and annulus pressures were being maintained within permitted operating limits.
CONCLUSIONS AND ACKNOWLEDGMENTS
Through the use of hands-on project management and development of a true teamwork approach to remedy construction, the $20.7 million remedy construction effort at the Hardage Criner project was brought in on time and on budget with change orders less than 2% of the project value. Costs were controlled by having a detailed understanding of the site conditions that was shared with all of the bidders. The HSRC worked diligently to establish and maintain an excellent relationship with the regulatory agencies that resulted in an "us and them against the problem" working environment. By doing this and not letting adversarial situations develop, problems were quickly identified and solved resulting in cost savings that, while difficult to quantify, were very real. As the years progressed, the HSRC never lost sight of the original project management goal of on time, on budget completion of the project with no reportable lost time accidents. This goal was always tempered with the fact that a project that performs as intended but does not totally meet the budget and schedule goals is considered a success while a project that totally meets the budget and schedule goals but does not perform as intended is not considered a success. We would like to acknowledge the hard work and dedication of the members of the Hardage Steering Committee; the members of the Hardage Site Remedy Corp.; the Board of Directors of the Hardage Site Remedy Corp.; Mr. J. R. Bradley, the HSC/HSRC Site Supervisor; Mr. Jerry Proffitt, NES Facility Manager; Mr. Mark Coldiron and Mr. Robert Roark, McKinney Stringer & Webster; IT Corporation; and Smith/Canonie. Perhaps the best tribute to the dedication and hard work of all of the people that contributed to the outcome at the Hardage Criner Site can be found in a few words of Theodore Roosevelt when he said:
"The credit belongs to the person who is actually in the arena: whose face is marred with dust and sweat:
who strives valiantly: who errs and may fall again and again, because there is no effort without error or
Table 1. Major Components of Hardage Site Remedy
|Component||Purpose or Function|
|1. Low permeability mudstone of Strata IV and
|Provide a natural barrier to vertical migration of constituents|
|V-shaped gravel-filled interceptor trench
constructed to the top of Stratum IV
|Provide hydraulic control of the source areas by capture of affected groundwater and NAPL for subsequent treatment|
|3. Composite cap over source areas||Prevent direct contact, control surface water flow in source areas, limit erosion of affected soils, and reduce infiltration of precipitation; active removal of vapors|
|4. Permanent vertical liquid recovery wells in
the Barrel Mound and Main Pit
|Extract pumpable liquids for off-site disposal|
|5. Southwest interceptor wells||Prevent migration of affected groundwater into North Criner Creek alluvium (achieved in conjunction with the V-shaped interceptor trench)|
|6. Water treatment system||Treat separately groundwater collected from the trench and Southwest wells to standards applicable for discharge to North Criner Creek|
|7. Natural attenuation and, if necessary,
control of migrations of constituents
presently found in the alluvial ground water a
|Cleanup the alluvial groundwater and prevent significant expansion of the area of affected groundwater|
|8. Institutional controls||Limit public access to affected areas, prohibit future withdrawal of affected groundwater, and continue public water supply to area residents|
|9. Ground water and surface water monitoring
|Monitor groundwater and surface water for continued effectiveness of the remedy|
a Remedy components not requiring design or construction
Table 2. Injection Well Profile Log Results
Table 2. Injection Well Profile Log Results
|8 August 1995
|Upper Noble Olson||4634-4670||29||7.73||22.1|
|Lower Noble Olson||4697-4738||32||4.22||12.1|