The Vehicle Assembly Building (VAB) at the Kennedy Space Center (KSC) is the active NASA space shuttle hangar and processing facility. The VAB was constructed in the mid 1960s for the Apollo Space Program and was retrofitted in the mid 1970s to support the Space Transportation System (STS "? space shuttle) operations. Geosyntec performed a series of RCRA facility investigations which identified and delineated a chlorinated volatile organic compound (CVOC) plume with a limited trichloroethene (TCE) source area (approximately 1/2 acre), along with a dissolved plume comprised primarily of vinyl chloride in excess of 100 acres. Based upon these findings, NASA asked Geosyntec to prepare a Corrective Measures Study (CMS), a Corrective Measures Design (CMD), and to implement site remedial activities.
Geosyntec's Scope of Services
Geosyntec conducted a biotreatability study, a source investigation using a membrane interface probe, and several detailed modeling activities. Based upon the results of these studies, Geosyntec prepared a CMS for the site that recommended a passive biostimulation approach for the TCE source area, biosparging for a high-concentration component of the vinyl chloride plume immediately upgradient of a sensitive surface water/wetlands area, and monitored natural attenuation (MNA) for the majority of the low-concentration dissolved plume. The CMD included the following primary features:
- Source area ethyl lactate biostimulation via a network of 45 injection wells strategically designed, screened, and located based upon the results of a 3-dimensional source model, with the spacing based upon the results of a bromide tracer study. The system was designed to deliver a 1% solution of ethyl lactate and groundwater on a 60-day injection schedule via a mobile injection trailer. We are performing monitoring in dedicated monitoring wells located within the source area.
- Dissolved plume discharge area treatment via a biosparge wall, which was designed based upon additional detailed vinyl chloride plume assessment (to identify the primary flow swath), using a network of 25 biosparge wells covering a length of 360 ft. The biosparge system is designed to operate as either a single or dual zone system.
- Monitored natural attenuation of a limited subset of monitoring wells located throughout the low concentration plume.
Geosyntec developed and implemented remedial measures at the site that have provided a passive, cost-effective source treatment resulting in source area monitoring well concentration reductions ranging from 75 to more than 99 percent during the first six months. We have also documented the performance of an operational biosparge wall to reduce vinyl chloride concentrations to below laboratory detection limits, and performed a monitored natural attenuation program for the low-concentration plume to document concentration decreases over time.