ARCHIVED REPORTS_XR0011980 - Laserfiche WebLink

Home Browse Search

Mr.Nuel Henderson, R.G January 31, 2003 Installation of Ozone Injection System and Remediation Status Report • Page 5 Chemical Oxygen Demand COD COD is the amount of oxygen required to degrade organic compounds in groundwater. Typically the COD concentrations are anticipated to decrease with a decrease in petroleum hydrocarbon concentration, resulting in increased dissolved oxygen levels. The COD concentrations varied from less than laboratory detection limits (<30 mg/L) to 60 mg/L in the groundwater samples collected on December 23, 2002, from onsite monitoring wells. Once in receipt of the analytical data from scheduled sampling events, Stratus will evaluate COD concentrations in groundwater and compare values to baseline concentrations. Stratus will continue to monitor the COD concentrations in groundwater, according to the monitoring plan, to evaluate for oxygen demand in the subsurface. Ferrous Iron Oxygen from degradation of ozone introduced in the subsurface can react with dissolved iron (ferrous) to form ferric oxide, an insoluble precipitate. This precipitate can get deposited in the screening area, thereby hindering ozone transportation. . The ferrous iron concentration in groundwater samples collected from select monitoring wells on December 23, 2002,were in the range of less than 0.1 mg/L to 3.9 mg/L. Groundwater samples from select monitoring wells will be analyzed periodically for ferrous iron and total iron to monitor for precipitation/clogging in the wells. Selected Chemicals of Concern TPHG, BTEX, MTBE and TBA are among the chemicals of concern that will be used to evaluate the performance of bioremediation at the subject site. Complete degradation of these chemicals will result in carbon dioxide and water. The quarterly analytical data for these parameters collected prior to ozone injection will serve as base line data, and this will be compared with analytical data collected after start-up of the ozone injection system to evaluate performance of C-Sparge'system. In addition to quarterly sampling, Stratus will collect groundwater samples from select monitoring wells on a monthly basis to facilitate performance evaluation of the ozone injection system. Plate Count and Nutrients Groundwater samples collected from select monitoring wells on December 23, 2002, were analyzed for heterotrophic plate counts and nutrients to establish baseline data. The data P:1Bp-Arco for UW54691ReportMrco 5469 Remediation Status Report.doc 5TRATU5