ARCHIVED REPORTS_XR0009365 - Laserfiche WebLink

Home Browse Search

nomena, and chemical transformations Thus, it is natural attenuation will not prevent impact to sensi- appropriate to evaluate and consider natural attenua- tive receptors, and other selected monitoring points tion when developing a corrective action plan for a site which will provide historical data for determining The recommended approach for evaluating natural plume characteristics attenu4ion which follows is based on simple analyses 4 If necessary,apply secondary indicators and conduct Iof actual site data and development of a confirmation more intensive analyses. If additional evidence of monitoring plan natural attenuation is needed,then secondary indica- I Plan site assessment activities to obtain the data tors such as geochemical data and more intensive needed to evaluate natural attenuation. Determine studies such as the mass balance approach,laboratory the direction, gradient and average rate of ground microcosm studies and detailed ground water model- water flow and the fraction of organic carbon in the ing can be conducted However at many sites, inten- ' soil to estimate the expected rate of plume migration sive studies may be impractical due to the extensive Measure D O levels inside outside, and upgradient data requirements and complex analyses Typically, of the plume to determine if sufficient D O is present mass balance and ground water modeling studies are for aerobic biodegradation and if an inverse correla- most meaningful at research sites where extensive tion between D O and solt-ble contaminant concen- monitoring and sampling networks have been trations exists Determine if natural or man-made installed At real' sites, monitoring will probably ground water recharge or discharge areas are present be required to verify natural attenuation even if I which increase aeratio,, of ground water Place mul- iptensive studies are conducted thus it is more prac- tiple monitoring points along thc. primary path of tical to rely on the primary indicators and natural plume migration and acquire historical data on the attenuation monitoring behavior of the plume along the longitudinal axis 5 Reevaluate the site after monitoring to determine Place a monitoring point at the leading edge of the the final corrective action. After monitoring the site plume to determine if the leading edge is migrating and acquiring sufficient historical data, it should be Obtain analytical results to he used for geochemical possible to determine if natural attenuation will or I indicators including pH Fe(Il) carbonate hardness will not prevent contaminants from impacting sense- and alkalinity and redox potential from ground water five receptors If natural attenuation will not be suffi- samples both inside and outside [he plume, ci,.nt then enhanced remedial alternatives should be 2 Apply primary indicators, to evaluate the extent of considered However if the data demonstrate that natural attenuation This review cif the, data Should natural attenuation protects human health and the includt. answering [he lollowina questions environment then natural attenuation is an appropri- • Do the phunt• indicate that natural ate final corrective action � frttrnuation iti uththiting1prei.airing migration of the These recommendations are intended to help tndus- J t ontamintint plume,' If the. plume. is rt-ceding is at try and regulatory agencies understand when significant ' steadv state or is migrating moire %lowly than ratura] attenuation is occurring and to implement prac- expeutd then significant natural attenuation is tical monitoring plans to assure that natural attenuation ciecurring if individual compounds exhibit unex- is sufficient to prevent impacts to sensitive receptors PLULd relaEwt. ratesot migration then preferential ' degradation tit certain compounds is likely • Uv D 0 cfn centrtuiain at tire we indicate aerobic References btodegradanon n likely' if background D O con- Barbaro J R J F Barkt.r L A Lemon and C I Mavfield centratuins are more than l to 2 mgiL and D O 1992 Biotransformation of BTEX under anaerobic deni- levels are depleted inside the plume relative to the. trifving conditions Field and laboratory observations I background then aerobic biodegradation is prob- Cant f1vflrology 11 245-72 able Also recharge areas for surface water can B,irh,tsh J E and Reinhard 1989 Abiotic dehaloge significantly incrLast_ D O levels in ground water of 1.2-dichloroethane and 12-dibromoethane in aqueous The: results of these inaivses should indicate if solution containing hvdrogen sulfide Env ScL & Tech 3 immediate remedial actions should be implemented 1349-58 I or if it is likely that natural attenuation is significantly Barker J F G C Patrick and D Major 1987 Natural attenua- tion of aromatic hydrocarbons in a shallow sand aquifer limiting contaminant migration and further monitor- Ground barer Monitoring Review 7, no 1 64-7I ing is warranted to confirm the extent of natural Bear J 1979 Hydraulicsofgroundwarer New York McGraw- attenuation Hili i Implement a monitoring program to confirm natural Caldwell K R D L Tarbox K D Barr S Fiorenza L E attenuation It the qualitative indicators suggest that Dunlap and S B Thomas 1992 Assessment of natural significant natural attenuation is occurring and is bioremediation as an alternative to traditional active reme- diation at selected Amoco Oil Company sites Florida In likely to prevent the contamination from impacting Proceedings of the 1992 petroleum hydrocarbons and sensitive receptors then a natural attenuation moni- organic chemicals to ground water Prevention, detection, I toring plan should be implemented This plan should and restoration conference, 509-25 Houston, Texas 4-6 include a sentinel well to provide early warning if November Dublin Ohio NGWA 172 a SPRING 1994 GWtHR