SITE INFORMATION AND CORRESPONDENCE_1993-2003

Home Browse Search

Draft Soils FS Memorandum -8- 14 September 1993 DDRW, Sharpe are relevant and appropriate in determining the standards by which an inactive landfill should be closed. Closure is an obvious source control measure for landfills which have released waste constituents to the waters of the State. Section 2581 of Article 8 requires construction of a final cover for closure of landfills in order to prevent infiltration of precipitation which may cause leaching of landfill constituents. Section 2550.12 of Article 5 also applies to the SWMUs at DDRW, Sharpe. This section requires Article 5 corrective action for all releases at the facility other than those from waste management units which have resulted in water quality impairment. The section states that: "A discharger seeking waste discharge requirements for the treatment, storage or disposal of hazardous waste shall institute corrective action as necessary to protect human health and the environment for all releases of hazardous constituents from any area at the facility other than a waste management unit regardless of the time waste was discharged at such an area" 23 CCR §2550.12(a) (emphasis added). DDRW, Sharpe has at least one waste management unit which has contributed to ground water contamination. Therefore, Article 5 corrective actions are applicable requirements for all releases of hazardous waste or hazardous constituents from all areas of the facility. 4. Dry Wells and Stormwater Runoff: The First Quarter 1993 Ground Water Monitoring Report (April 1993) was reviewed and commented on in a Board memorandum, dated 3 August 1993. This memorandum was distributed, along with the 95% Remedial Design comments on 30 August 1993. The memorandum points out that the arsenic concentration in MW-407A was 1030 µg/I which far exceeds the Primary Maximum Contaminant Level (MCL) of 50 µg/l. This concentration represents a new high for arsenic at this site (previous high was 700 µg/l). This well has also historically had the highest bromacil concentrations, however, bromacil is not monitored in a regular basis in this well. This dramatic increase in the arsenic concentration may be due to the extreme wet season that occurred during this quarter and to the dry wells (which are located along the western border of the site in this area) which are used to manage runoff. There appears to be a strong correlation between the dry wells and the arsenic and bromacil concentrations found in this well. The dry.wells should be abandoned, as we believe that these contribute to the high contaminant concentrations in this area. Monitoring of the runoff in the area of the dry wells is warranted to determine if the increase in contaminant concentrations in MW-407A are related to runoff. This may require a modification of the storm water National Pollutant Discharge Elimination System (NPDES) permit (No. 92-184). Bromacil should also be monitored on a regular basis in MW-407A and in the stormwater runoff. This area is in Plume 3 and should be captured by the Central Area extraction system. If the increases in arsenic, bromacil or other pollutants, are related to the dry wells and the storm water runoff, Sharpe will have to develop a plan to prevent this in the future. This may require different management of the storm water runoff and may require wellhead treatment as pretreatment for water from this extraction well. Dilution with other extracted water is not an acceptable solution to the problem. Ground water treatment is estimated to last approximately 40 years, however, if Sharpe continues to use dry wells for management of the storm water runoff, this