CO2 and Water
Dr. Lehmicke has worked in the bioremediation industry for 28 years and currently specializes in the natural attenuation (NA), abiotic degradation and active bioremediation (EISB) of chlorinated solvents. He has worked on over 120 such sites, evaluating the feasibility of NA and EISB, costing and designing remedies and doing 3rd party reviews. He has also worked with zero valent iron (ZVI) and active bioremedies for some emerging compounds. He worked for several consulting firms prior to working on his own.
Rehabilitating a Physically Plugged Permeable Reactive Barrier
A large zero valent iron permeable reactive barrier (ZVI PRB) became physically plugged after two years of operation, resulting in ground water being deflected around the PRB. Collection of 4”cores at the up gradient face of the PRB allowed rapid flow through, indicating the obstruction on the up gradient face was < 3” thick. The sulfate concentration in ground water was between 50 and 90 mg/l. The plugging was believed to be a combination of precipitates (i.e. sulfides from sulfate reducers), bacterial biomass, loss of porosity due to iron decay, and possibly, gas bubble formation. Interim measures included biobariers installed down gradient of the PRB and at the end where ground water was bypassing it while a lab study was performed to identify a remedy for the plugging. The results should help anyone working on a ZVI barrier that appears to be plugged physically.