Performance Based Cleanup

The site is located near the point between the Sebastian River and the Indian River in Florida. The facility is located near the top of ridge of sand between the rivers and approximately 20 feet above the elevation of the rivers.

The facility was gas station, and is now professional office condominiums. A Discharge Report Form (DRF) was filed for a release identified at the referenced site when it was a gas station. Financial liability was retained by the FDEP for the assessment and remediation. The site is underlain by layers of sandy soil and organics. The sandy soil between 12 and 25 feet bls contains a significant percentage of organic material.

The USTs for the site were removed and replaced in 1992. An assessment was conducted for the discharge during 1994. An Air Sparging and Soil Vapor Extraction (AS/SVE) system operated during 2005 and 2006. The system was abandoned when the site was redeveloped.

In 2008, chemical injections were conducted (hydrogen peroxide injections with Fenton’s reagent) were conducted through 22 injection wells, followed by Natural Attenuation Monitoring.  The injection wells were abandoned. The results of groundwater sampling for Post-Active Remediation Monitoring (PARM) identified the continuing presence of petroleum constituents in the groundwater above the State’s Groundwater Concentration Target Levels (GCTLs).

MAS Environmental prepared a RAP Modification (RAP Mod) and negotiated a Performance Based Cleanup work order to provide remediation of the remaining petroleum constituents (BTEX, MTBE and naphthalene). The FDEP was also concerned that dissolved iron concentrations remained high in the treatment area, and that the dissolved iron concentrations were the result of the chemical injection remediation process. The RAP Mod provided a remediation design that included groundwater extraction, treatment and re-infiltration of the treated water.

The fixed price allows MAS to provide complete remediation services, and establishes the end goal for the remedial activities. Because MAS is providing these services under the guaranteed performance agreement, MAS is only paid by meeting the project milestones.

The project has begun, and we anticipate meeting all of the goals (including the completion of 4 quarters of PARM) within two years.

Large urban Chlorinated Solvent Assessment

Chlorinated solvent contamination was discovered beneath a property during petroleum assessment and remediation activities. The petroleum impacts were determined to be below state guidance concentrations and the site received a Site Rehabilitation Completion Order (SRCO) for the petroleum impacts. The assessment of the chlorinated solvent plume in this urban area is ongoing.

The MAS assessment of the plume has resulted in cross sections and horizontal mapping of the soil types and the primary solvents in this plume (Tetrachloroethene, Trichloroethene, and Vinyl Chloride). The assessment has assessed the solvents carefully at multiple depths, and is evaluating whether multiple sources exist in this urban area. Orientation of the soil layers, groundwater flow directions, the phase of the solvent (dissolved or free-phase) play significant roles in the transport of the contaminant mass.

MAS has successfully obtained access agreements to install and sample the required wells.

Gas Station Alternate Procedure (High Vacuum Dual Phase Extraction)

On September 27 and 28, 2008, closure assessment activities were conducted during the removal of the three 8,000-gallon capacity gasoline USTs, three 4,000-gallon diesel containing USTs, and an additional non-registered empty 3,000-gallon UST.  Once the tanks were removed, two 12,000-gallon double walled fiberglass steel tanks with new lines and pumps were installed in the same location.  A confirmation soil sample (SA-1) was collected from the center of all the USTs.  Benzene was reported at the Method Detection Limit (MDL) of 58.2 milligrams/kilograms (mg/kg).

Subsequent soil and groundwater assessment activities identified low concentrations of petroleum constituents. The contaminants were identified in the groundwater at concentrations above the State of Florida Groundwater Concentration Target Levels (GCTLs) but below the Florida Natural Attenuation Default Concentrations (NADCs). It was determined that the quick remediation of the site would be more advantageous than quarterly or semi-annual sampling while hoping that natural attenuation occurred. 

The groundwater table of the shallow surficial aquifer was observed to be at approximately 12-13 feet below land surface (bls).  The lithology is composed of fine sand from 0-8 feet bls and slightly clayey sand from 8-30 feet bls.  A potential semi-confining layer of stiff clayey sands was encountered from approximately 30-36 feet bls.

A High Vacuum Multi-Phase Extraction (HVMPE) system was used to extract and treat the petroleum impacts near the newly installed USTs. No trenching was required. Two quarters of Post-Active Remediation Monitoring (PARM) groundwater sampling did not identify any petroleum constituents.

After two (2) additional quarters of groundwater sampling without dissolved petroleum constituents, a Site Rehabilitation Completion Order (SRCO) will be requested.

Selected Projects

Your Partner in Environmental Solutions.

MAS has successfully worked on a wide variety of environmental related projects.   The selected projects below are a sampling of the work that MAS has done recently.  For more information, do not hesitate to give us a call at (813) 658-8823.

In the last five years, MAS has successfully obtained Site Rehabilitation Completion Orders (SRCOs) or similar site closures on over 25 facilities.