Former Sawmill Pond Closure
SCOPE OF SERVICES
Soil Sampling Collection
Soil Disposal Oversight
Site Closure Activities
Former Sawmill Pond Closure, Camino, California
The Site was used as a center for lumber production for approximately 107 years until operations concluded in 2009. Lumber production activities at the site included operation of a paved log deck for log storage, lumber milling and planing, wood treatment, lumber drying, box manufacturing, materials shipping, mill equipment repair, vehicle and heavy equipment repair and service, and railroad maintenance and locomotive repair. Runoff from the log deck was contained on the site in a series of four ponds used for storage and recirculation back to sprinkle the logs on the deck. Upon cessation of milling activities and decommissioning of the mill, the Waste Discharge Permit issued to the site by the California Regional Water Quality Control Board that included monitoring of the pond system, was rescinded. As a part of the requirements for permit closure, pond sediment was removed and the ponds were clean—closed. To prepare for sediment removal, the remaining liquids were pumped to and sprayed on the approximate 20-acre paved log deck and existing ditch system where the water was evaporated during the warm to hot weeks of June and July.
Since the ponds had been inactive for several years, the conditions prior to sediment removal consisted of saturated sediments with heavy vegetative growth. Removal of the accumulated sediment from the ponds was completed by October 1, 2012. Stratus personnel obtained a site assessment/investigation permit from the El Dorado County Environmental Management Department (EMD), and collected confirmation soil samples from the pond bottoms for laboratory analysis. Sampling was conducted with hand tools in saturated clayey soil conditions, and from moderately weathered metasedimentary rock.
Pond sediment removed to clean-close the basins was stockpiled on the paved log deck and dried. Characterization of the stockpiled materials was conducted to determine the concentrations of any of the constituents of concern that might have been contained in the sediment. The characterization information was used to evaluate the most practical method of sediment disposal, or if re-use on site would be appropriate.
Confirmation soil samples were collected from the native materials of the pond bottom following sediment removal, and analyzed at a California DHS certified environmental laboratory for the following constituents/parameters:
pH by EPA Method 9045C;
Total Extractable Petroleum Hydrocarbons by EPA Method 8015 M (following a silica gel preparation - EPA Method 3630B);
Metals - aluminum, copper, lead and zinc by EPA Method 6010 (total concentrations); and
Tannins and lignins by SM 5550B.
The confirmation sample analysis results indicated that removal of the sediment had been completed successfully, and that none of the constituents of concern were detected at levels that required additional pond bottom excavation. California Regional Water Quality Control Board staff approved backfilling of the ponds.