ARCHIVED REPORTS_XR0005705 - Laserfiche WebLink

Home Browse Search

1 r • Wellhead vacuum • Vapor extraction rates rGroundwater extraction rates • Vapor hydrocarbon content ' Extracted groundwater quality i Following the pilot test,additional monitoring may be conducted to assess the rate at which system r characteristics return to equilibrium vapor Analysis of or extraction data obtained during pilot testing is similar to that for SVE pilot testmg Y p ' Parameters related to groundwater extraction,such as extraction flow rate and water table drawdown, are also analyzed Groundwater modeling data may be used to determine required well spacing To address ' varying soil characteristics across a site,full-scale systems may be designed,built, and operated in a phased approach to capitalize on operating data obtained from wells installed during earlier phases (Tetra Tech 1996a) Smaller full-scale systems may be designed using available physical and theoretical data to avoid incurring costs associated with pilot testing Typically, when a pilot test is not conducted,both well spacing and extraction equipment are conservatively sized to ensure that the system will perform at expectations or ' better 4.3.1 2 Extraction Well Design Generally,DPE wells are designed with screened intervals above and below the groundwater table at the 1 location of greatest contamination Selected screen depths must consider the hydrogeology and extent of dewatering required The lower portion of the extraction well screen and filter pack are generally sized using guidelines for groundwater extraction (WDNR 1993)to prevent entrainment of fines into the extraction system Well diameter is based on site-specific design factors similar to those for SVE and on requirements of the type of DPE employed, the diameter must be large enough to accommodate any ' downhole apparatus associated with extraction system requirements Existing monitoring wells with 4-6 r r