ARCHIVED REPORTS XR0012541 - Laserfiche WebLink

Home Browse Search

W - s > r � a x' ` rte•d S �x ti File No.2070-2 19 December 1491 Page 11 5.1 In-situ Grouri lwater Treatment In-situ groundwater treatment is accomplished by injecting petroleum hydrocarbon consuming bacter;al microbes along with required nutrients into the contaminated aquifer. The bacterial microbes biologically detoxify the organic contaminants by convertin; them to harmless byproducts z ach as carbon dioxide and water. In-situ treatment systems can be r.latively low cost remediation alternatives. A relatively small capital expenditure is required and disposal of the treated groundwater is :usually not necessary. However, limited success is usually achieved via this treatment method due to subsurface formational restrictions which limit the movement of the bacteria] microbes. Further complicating this treatment method is the difficulty involved in maintaining optimum conditions (amp]e oxygen. and nutrients, for example). For these reasons, this treatment method usually needs to be supplemented by a chemical or physical treatment method (Proceedings of Petroleum Hydrocarbon , and Organic Chemicals in Ground Water: Prevention, Detection ar'.,i Restoration, 1988). Since the majority of the subsurface soil conditions at the Rainr Bakery site consist of silt and clay, this treatment method would be expected to achieve only limited success (as a result of formational restrictions), We therefore do not recommend this treatment alternative for the Rainbo e Bakery site. 4 . 5.2 Groundwater Extraction Systems Groundwater extraction systems involve the removal of the contaminated groundwater from the R' aquifer via extraction wells. The contaminated groundwater is tier, process4i via a treatment system and the treated groundwater discarded. u Four commonly used alternatives exist for the treatment of extracted groundwater contaminated wit�t petroleum hydrocarbons, The treatment alternatives can be classified as biological, chemical and physical treatment systems. Following are brief explanations of these treatment alternatives and their applications to the Rainbo Bakery site. 5.2.1 Groundwater Extraction and Biological Treatment r This groundwater .lreatment alternative first requires the extraction of the contaminated groundwater from the aquifer via a groundwater extraction a system. The contaminated groundwater is then transferred to a specially constructed containment basin. While in the containment basin, the contaminated groundwater is treated in the same manner as the in-situ y: biological treatment method previously discussed. However, since the contaminated groundwater is extracted prior to the introduction of microbes and nutrients, a more accurate monitoring of pertinent variables such as nutrients, temperature, flow rate, etc., is possible. 7 1is allows for a more , efficient treatment of the contaminated groundwater to be performed. 1 Upon completion of the biological treatment, the treated water is discarded. I ANDERSON CONSULTING Y1 GROUP r.