Bioremediation Treatment Tests, Crows Landing, CA
|OTIE evaluated the effectiveness of enhanced in situ bioremediation (EISB) technology to reduce primary COPCs to below site-specific RAOs at Crows Landing. The COPCs in the Administration Area Plume are 1,2-DCA, carbon tetrachloride (CT), and benzene. This included evaluation of aerobic remediation processes at UST Cluster 1 and UST Site 117, consisting of biosparge at UST Cluster 1 and injection of an oxygen releasing compound at UST Site 117. The project scope for IRP Site 17 included evaluation of anaerobic processes consisting of three phases of subsurface injections of three different organic substrates.
UST Cluster 1: For Phase 1, OTIE installed two upgradient and one downgradient groundwater monitoring wells, installed 32 biosparge injection wells and a biosparge system, and performed six months of biosparge operations using injection of compressed air, and six months of groundwater and vapor progress monitoring. For Phase 2, OTIE performed six months of biosparge operations using injection of compressed air and six months of vapor and groundwater monitoring. For Phase 3, OTIE performed three months of biosparge operations and vapor and groundwater monitoring and a rebound test. Results demonstrated successful operation of the biosparge system over 15 months and virtually no rebound after 6 months of system shut-down.
UST Site 117: OTIE installed upgradient and downgradient groundwater monitoring wells, drilled four shallow and 11 mid-shallow temporary borings, and injected an oxygen-releasing compound (ORC-Advanced) and 12 months of groundwater monitoring. Results demonstrated increased dissolved oxygen in groundwater and decreased COPC concentrations. In one year following injection, 1,2-DCA concentrations were reduced by 50% in the center of the source zone, and benzene concentrations decreased from approximately 100 ug/l to 13 ug/l.
IRP-17: For Phase 1, OTIE installed upgradient and downgradient groundwater monitoring wells, drilled six mid-shallow temporary borings, installed four injection wells, and performed injection of two different substrates into the mid-shallow and mid-deep zones and six months of groundwater progress monitoring. For Phase 2, OTIE performed injection of one substrate into the mid-shallow and mid-deep zone, and six months of groundwater progress monitoring. For Phase 3, OTIE provided delineation of the upgradient extent of the dissolved CT plume, injection of a more cost effective substrate into the shallow, mid-shallow, and mid-deep zones, additional baseline sampling, and post-injection sampling. Results indicated that the injection of vegetable oil at IRP Site 17 significantly altered the geochemistry of groundwater in the area and, thereby, stimulated the very rapid reductive dechlorination of the CT present at the site.
|Client Name: NAVFAC Southwest
Location: Crows Landing, CA
Contract Value: $2M