Black's Dry Cleaner's Case Info.

BIO REM

'Nature's Way'

Environmental Products

and

Soil & Water Decontamination Services

The ORIGINAL Bio Rem Company since 1989

The objective of this site investigation at Black's Dry Cleaners was to access the subsurface extent and likely source of a known tetrachloroethylene release at the site. Furthermore, selected soil and groundwater samples collected during the investigation were screened for Stoddard Solvent using gasoline-range petroleum hydrocarbon analyses. The purpose of the Stoddard Solvent assessment was to investigate for contamination remaining in soil and groundwater from a previous release associated with two underground storage tanks (USTs) at the north end of the site. These tanks were removed and soil remediated in 1995.

Site investigation activities were designed to meet or surpass the objectives. Invasive investigation techniques consisted of the drilling of twelve geoprobe soil and groundwater sampling boreholes. Six of these boreholes were drilled with a van-mounted hydraulic push geoprobe unit operated by GeoTech Explorations Inc. Six other boreholes were drilled with a hand-operated jackhammer equipped with geoprobe sampling rods. Collected soil and groundwater samples were analyzed by EPA Method 8010 for a suite of halogenated volatile organic compounds which includes tetrachloroethylene, trichloroethylene, and dichloroethylene (commonly found in dry cleaner solvents). Selected soil and groundwater samples were also analyzed by method NWTPH-Gx and EPA Method 8020 to evaluate the possible presence of previously undetected Stoddard Solvent from an earlier UST release at the site.

A water sample was also collected from the nearest groundwater supply well. This well, located at Portland Nursery approximately 1/4 mile northeast of Black's Dry Cleaners, is used for irrigation and is thought to draw water from the Troutdale Gravel Aquifer (a regional drinking water aquifer). This groundwater sample was also analyzed by EPA Method 8010 for halogenated volatile organic compounds and EPA Method 8020 for BTEX.

Site Description:

The project site is a rectangular property, with the west half of the property occupied by a building which is presently being renovated. The east half of the property is an asphalt paved parking area. An L-shaped, grass covered portion of the property bordered the north and northwest edges of the site. The portion of the grass-covered area bordering the north edge of the site was paved with concrete blocks for use as a parking area by the staff of Black's Dry Cleaners. These blocks have molded openings in them which allow grass to grow through them and rain water to infiltrate into the subsurface.

Apparent Problem:

Analytical results from soil and groundwater samples collected at the site in the summer of 1999 confirmed that a release of tetrachloroethylene had occurred. Lower concentrations of some associated compounds (trichloroethylene and dichloroethylene) were also found. The contamination was beneath the south half of the store appears to be centered around a drain in an open utility trench located near the north wall of the south half of the building. The south half of the onsite building does not appear to require remedial action.

Apparent Offsite Migration of Contaminates:

Sampling by a tank service company identified contaminates in soil and groundwater near the project site. Analytical results from the soil samples indicated that a release of heating oil had occurred from one or more of the tanks. Analytical results of the groundwater sample showed detectable concentrations of dry cleaning solvents. All of the analyzed groundwater samples contained detectable concentrations of tetrachloroethylene (and decomposition products).

Because groundwater is thought to flow west and samples were collected so close to the apartment building it is presumed that similar contaminant concentrations are present in groundwater under the apartment building.

Geology and Hydrogeology:

A USDA Soil Conservation Service Report for Multnomah County indicated that soils beneath the subject property have been identified as Urban Land-Latourell Complex. In most areas of this complex, soils have been graded, cut, filled, or otherwise disturbed. In undisturbed areas the soils (which grade downward from dark brown to yellowish-brown loam) are moderately permeable, whereas in areas that have been cut or filled the soil permeability is variable.

During preliminary soil and groundwater sampling conducted at the site, RNSA geologists inspected shallow soils beneath the Black's Dry Cleaners property. The building has between one and three feet of gravel fill beneath its concrete slab floor. The fill material overlies a fine grained yellowish-brown silty clay with minor gravel. Stratigraphy outside the building was found to be similar to that found beneath the building. The exception being the presence of a six to twelve-inch thick layer of diatomaceous earth (understood to be Stoddard Solvent filtration media discarded during early years of dry cleaner operation) buried beneath approximately one to two feet of debris-filled topsoil outside the back door in the northwest corner of the lot.

RNSA conducted a review of the Oregon Water Resources Department Database for wells drilled in the vicinity of Black's Dry cleaners. One well was identified to be within approximately 1/2 mile of the property. On the basis of site topography and known regional groundwater flow directions this well is presumed to be cross-gradient from the site. A groundwater sample was collected from this well and analyzed for halogenated volatile organic compounds and gasoline-range constituents as part of this study. Low concentrations of chlorinated solvents were found in the water.

Site Topography:

The subject property is generally flat-lying. The asphalt-paved parking area on the east half of the subject property drains radially to a catch basin located approximately at the center of the lot. The northwest corner of the site is elevated approximately 3.5 feet above the adjacent property to the west. This topographic feature is presumed to be artificial (i.e. the result of excavation of the adjacent property or filling of the subject property during construction). Regional topography slopes to the west-northwest from a subject property. No surface water bodies are present in the general vicinity of the site.

Scope of Project:

Bio Rem's H-10™ product was chosen to remediate the compounds of this site. The application methods, monitoring, and all other directions needed were communicated to Hart Crowser, the on site operational engineers and consultants under the supervision of the Department of Environmental Quality (DEQ) for Black's Dry Cleaners Site in order for them to do the project themselves with the use of Bio Rem's H-10™ and support.

Due to the fact that the source area soils were excavated and replaced with gravel and several irrigation pipes, the addition of the appropriate volumes of Bio Rem H-10™ solution should be relatively easy. Based on the diagram and subsequent discussions Black's Dry Cleaners will add the solution according to the directions of Bio Rem. Once they have properly completed all necessary applications they will next have to monitor the site. In order to properly monitor this program, we not only need to track the degradation of PCE, but also breakdown compounds (TCE, DEC). It is anticipated that these daughter compounds will increase as the PCE degrades. Water and soil samples should be taken every 30 days, and should include points under the source area.

In addition to monitoring the contaminates, total Heterotrophic bacteria (plate count) should be run on the groundwater, as well as Chlorides, pH, Dissolved Oxygen, and nitrogen concentrations. These tests will track the progress of the bacteria. However, once the bacteria are in the contaminant plume, there are no additional sources of oxygen or nutrients required for the H-10 to completely biodegrade the contaminants. The project is a work in progress and is currently being monitored in order to track final results.