Laserfiche WebLink
is unknown Air spargmg should increase the effective removal of gasoline <br /> hydrocarbons from groundwater beneath the site and increase available oxygen in the <br /> ' subsurface for naturally occurring biodegradation Some uncertainty exists about the <br /> effectiveness of the vapor extraction system in removing all the documented gasoline <br /> hydrocarbons in the shallower less permeable soil However SJCPHS-EHD has <br /> indicated they will negotiate site specific cleanup standards for soil beneath the site <br /> based on and evaluation of additional benefit for costs incurred <br /> i <br /> i <br /> C Criterion b <br /> The long term effectiveness for soil remediation would be good depending upon the <br /> ' degree of contaminant removal Groundwater would be monitored periodically to <br /> ensure that the impact to groundwater is declining <br /> o Criterion 7 <br /> This alternative has some implementability problems due to the time involved in <br /> obtaining permits from the APCD for the vapor extraction system, obtaining <br /> encroachment permits, installing additional sparge wells, performing sparge test, and <br /> trenching in public right-of-way for underground air sparge conveyance Imes <br /> Permitting could take as much as 180 days dependant upon APCD work load, but is <br /> typically completed in 50 to 90 days <br /> o Criterion S <br /> Impact to the adjacent businesses during installation and other site activities may be <br /> considerable due to the number and locations of offsite air sparging wells needed <br /> This method has been shown to be effective in similar soil types and regulatory <br /> F ' acceptance is expected <br /> 3.3.5 Alternative 5 - Soil Vapor Extraction with Groundwater Extraction <br /> o Criterion 1 <br /> P <br /> ' This alternative has minimal health-based risks Gasoline hydrocarbons are removed <br /> from extracted vapor and groundwater prior to release/discharge minimizing the risk <br /> of exposure to humans The potential fire or explosion hazard would be minimized <br /> ' with a properly designed system and regularly scheduled monitoring and <br /> maintenance <br /> z ' a Criterion 2 <br /> This alternative would reduce the toxicity, mobility and volume of contaminants in <br /> the soil and groundwater <br /> groundielrncklcap 18 <br /> i <br />