GROUNDWATER PUMP AND TREAT SYSTEMS

Client: Confidential, Trucking Distribution Facility, Rural Southwest Virginia — Final Design, Installation, and Operation of a Groundwater Pump-and-Treat System

Problem:

Dissolved Gasoline Compounds in Shallow Clay Overburden

Solution:

Installation of 11 recovery wells equipped with pneumatic pumps and treating groundwater with a low-profile air stripper.

Scope of Services:

In response to a subsurface release of gasoline from a ruptured flexible connector during 1989, SCS modified a preliminary design prepared by the client and previous consultants. Final design included operation of pneumatic total fluids pumps in 11 existing shallow overburden groundwater wells.

VOCs were recovered from groundwater by a low-profile air stripper. The air stripper was installed outdoors on a concrete pad. Additional mechanical equipment provided with the system included a 15-horsepower air compressor, a refrigerant air dryer, oil coalescing and particulate air filters, and an electrical control panel.

Once the system was constructed and permitted by the Virginia Department of Environmental Quality (VDEQ) for surface water discharge, SCS operated and maintained the system for an initial contract period of one year. SCS performed monthly sampling of the influent and effluent of the groundwater remediation system, along with quarterly reporting to VDEQ under the Corrective Action Permit.

GROUNDWATER REMEDIATION DESIGN/BUILD

Client: Bulk Oil Storage Terminal - Groundwater Remediation System Design/Build, Ferrysburg, Michigan

Problem:

Release of petroleum products from a bulk fuel storage terminal to a shallow aquifer in a coastal marine environment

Solution:

Design, install, and operate a groundwater remediation system.

SCS performed a series of environmental investigations at a bulk petroleum storage terminal in Ferrysburg, Michigan to evaluate the extent of soil and groundwater contamination at the terminal as a result of past releases from leaking USTs and terminal operations. The investigations were performed under the regulatory guidance of the Michigan Department of Natural Resources and in accordance with the Michigan Environmental Response Act: 1982 Public Act 307 as amended (MERA).

Environmental investigations performed included the drilling of soil borings, installation of clustered groundwater monitoring wells designed to evaluate specific hydrogeologic zones, soil sampling and analysis, a soil gas survey, groundwater sampling and analysis, sediment and surface water sampling and analysis, slug testing of selected wells, and contaminated soil excavation and disposal. During the environmental investigations, free- phase product (both gasoline and fuel oil), petroleum compounds dissolved in groundwater, and petroleum contaminated soils were carefully identified and delineated.

Based on the site characterization, SCS prepared a Remedial Action Plan (RAP) for the site in accordance with MERA. The RAP included remedial measures for both soil and groundwater contamination, and was approved as an "Interim RAP" in 1994. SCS prepared design plans and specifications for the soil and groundwater systems. Utilizing the design drawings, SCS Field Services constructed the groundwater treatment system at the facility. Construction included: modification of existing electrical systems; construction of a pre-engineered treatment building; installation of treatment process equipment; installation of two recovery wells; installation of aboveground fluids piping with jacketed, steam-traced insulation.

Groundwater at the site is removed from two recovery wells, and treated using a low-profile air stripper designed to remove volatile organic compounds (i.e., BETX), foll owed by two liquid-phase carbon adsorption beds in series to remove less volatile petroleum compounds (i.e., MTBE, naphthalene, etc.). Treated groundwater is discharged to surface waters under an NPDES permit issued by MDNR.

Both of the recovery wells are equipped with a dual pump system. An electric submersible pump is utilized to remove groundwater from each well, and a pneumatic product-only pump is used to remove floating hydrocarbons and place them directly into a holding tank for subsequent fuel blending. Limited soil excavation was performed in source areas of former tanks and loading areas.

Performance evaluation was performed to assess the adequacy of the Interim RAP. MDNR has approved the groundwater treatment system for a final remedial measure.

INVESTIGATION AND CORRECTIVE ACTION

Client: Department of Public Works, Herndon, Virginia - Underground Storage Tank Release Investigation, Interim Corrective Action Site Characterization Report for the Former Herndon Town Shop, Virginia

Problem:

Soil and groundwater contaminated with gasoline and diesel fuel.

Solution:

Free product removal and a groundwater pump-and-treat system with recovery well field in a shallow bedrock system.

Scope of Work:

SCS conducted precision tank tightness testing of three underground storage tanks (USTs) at the Town of Herndon's (the Town's) former public works maintenance facility (cars, trucks, heavy and light equipment, chemicals, paints and other and materials, etc.). One of the USTs was found to be leaking. SCS assisted the Town with the removal of this tank. SCS then conducted a site investigation at the facility to determine the extent of the release. Numerous borings were drilled in bedrock and converted to groundwater monitoring wells. Free product was detected in a downgradient monitoring well at the property line. Upon completion of the initial investigation, a comprehensive site assessment, risk assessment, and remediation assessment was performed, including the analysis of the potential migration pathways for petroleum compounds.

SCS prepared a written program for removal of free product that was implemented by Town personnel. SCS supervised the recovery of free product, and recorded bi-monthly water levels and product thickness measurements. Public utilities were screened and monitored for organic vapors to determine if subsurface utilities were impacted, and a limited off-site soil gas survey was conducted. SCS subsequently installed an additional 18 groundwater monitoring wells, two pump test wells, and three piezometers, extending some 2,000 feet downgradient from the location of the release. Two, 24-hour, draw down pump tests were performed, along with slug testing of four other wells. Numerous test pits were excavated along sanitary sewer lines, and samples were obtained from wet- weather ditches and surface waters.

Gravel interceptor trenches were constructed in the flood plain area adjacent to the surface waters. Free product recovery equipment was installed in several on-site wells, along with groundwater depression pumps. A low-profile air stripping unit was installed in a prefabricated structure, and pretreated groundwater was temporarily discharged to the sanitary sewer.

Ultimately, the site characterization was completed; the risk assessment performed; and remedial endpoints formulated based on the surface water receptors and proposed development of the site. A Corrective Action Plan (CAP) was prepared and submitted to the Virginia Department of Environmental Quality (VDEQ), and subsequently approved.

SCS is currently operating four recovery wells with dual pump systems (total fluids and free product). Groundwater is treated with a low-profile air stripper, polished with activated carbon, and discharged to the storm sewer. Off-gas from the air stripper is abated with vapor-phase carbon.

SPCC PLAN

Client: U.S. Department of the Navy, Naval Surface Warfare Center, Dahlgren, Virginia - Implementation of SPCC Plan at the Naval Surface Warfare Center, Dahlgren, Virginia

Objective:

To prepare Spill Prevention, Control and Countermeasure (SPCC) plan improvements for the Naval Surface Warfare Center (NSWC).

Approach:

Under an indefinite quantity contract, SCS was asked to prepare SPCC improvements for 235 sites throughout the NSWC in Dahlgren. SPCC improvements were designed for drum storage areas, small above-ground heating fuel tanks and above-ground waste oil tanks.

Specifically, SCS provided designs for a protective vault and whistle vent alarms at 228 existing tanks; level indicators at two sites; high level alarms at four sites; containment dikes and high level alarms at 11 sites; containment dikes at six sites; contained parking at two sites; and a high level alarm, containment dike and truck unloading facility at two sites.

The project also included the addition of a high density polyethylene liner for a 1,200,000 gallon above-ground No. 2 heating fuel oil storage tank and a 42,000 gallon above-ground No. 2 heating fuel tank servicing the facility's power plant. Other services provided included new vent piping, whistle vent alarms and spill containment fill manholes to over 150 family housing units basewide.

UST MANAGEMENT

Client: Fairfax County Water Authority, Merrifield, Virginia - Underground Storage Tank Management Services, Fairfax, Virginia

Problem:

Services to multiple sites concerning USTs.

Solution:

Provide UST services ranging from inventory and testing to design and replacement. This project included the following range of services for underground storage tank (UST) management:

• Tank inventory
• Testing
• Leak detection recommendations
• AST and UST design
• UST closure
• Site Characterization Reports
• Corrective action designs
• Other services as required

SCS was retained by Fairfax County Water Authority (FCWA) to provide underground storage tank management services at multiple sites. A comprehensive UST inventory and tank tightness testing have been performed. Site checks were performed at USTs suspected of leaking. The site checks consisted of soil gas surveys, subsurface sampling, monitoring well installation and sampling, and completion of written reports. Following acceptance of the written reports, SCS has been asked to design replacement underground storage tanks.

As a result of these reports, SCS prepared specifications and drawings for the upgrade, removal, or replacement of ten USTs at seven different locations. The replacements included the installation of new underground and aboveground storage tanks. The new designs included automatic tank gauging, spill and overfill protection, cathodic protection, leak detection positive pressure piping, and card key fuel management system. Specifically the new design for the aboveground storage tanks included specifying tanks that meet the new UL2085 for bullet impact resistance, and having a two hour fire rating.

Following the design, SCS assisted FCWA in pre-qualifying contractors, soliciting construction bids from contractors, reviewing the contractors bid, contacting the contractors references, and finally making a recommendation to FCWA. SCS provided full-time construction oversight throughout the construction to include submittal review, change order processing, invoice review, and other administrative functions.

One of the largest projects performed under this contract was the investigation and corrective action for a No. 2 fuel oil release at the Corbalis Water Treatment Plan. SCS first conducted surface and subsurface investigations for suspected hydrocarbon contamination. The initial samples were collected with a hand auger.

Subsequently, SCS conducted further investigations by installing monitoring wells in the vicinity of the piping release. At this stage, a risk and remediation assessment was performed and a site characterization report submitted to the Virginia State Water Control Board.

To recover the free product, SCS installed three recovery wells and QED seeker pumps. Emergency response services were provided to prevent free product from entering state waters. SCS designed and implemented an oil recovery and water treatment system. Following this, the adequacy of the interim corrective actions were assessed, including an investigation into how the release will affect proposed construction at the site.

The final task performed at the Corbalis site was the removal of five USTs, including oversight during tank removal and backfilling; tank and excavation inspection; collection and analyzing of soil samples; and the submittal of a closure report.

During construction of new structures at this plant, free product and contaminated groundwater were managed by SCS. A 100,000 gallon holding tank was constructed to contain excavation waters. Free product was recovered from trenches, sumps, and dewatering wells. Contained water was treated with granular activated carbon, and discharged by permit to the sanitary sewer system. Petroleum contaminated soils excavated for foundations were staged within a PVC-lined bermed area, covered, and secured. Upon completion of excavating activities, SCS solicited bids for the off-site treatment of the soils. Approximately 4,000 tons of material was thermally treated at an off-site facility.