Recommended Groundwater Monitoring Program for Hydrogen Release Compound (HRC®) Pilot/Full Scale Treatment

Monitoring of selected wells should be conducted to validate the HRC-based enhancement of reductive dechlorination processes. The monitoring well network would ideally include wells from the following locations:

• Inside treatment area: Provides information on geochemical conditions and contaminant trends induced by HRC.
• Downgradient of treatment area: Provides information about residence time effects. Since the contaminant has to be in contact with the electron donor for a given length of time, the actual performance may be evident at downgradient locations for sites with moderate to high groundwater velocities.
• Upgradient of treatment area: Provides a measure of contaminant mass and competing electron acceptor load entering treatment area.
• Background: Allows comparison of geochemical changes induced by addition of HRC.

An initial or "baseline" round of sampling should be performed to identify pre-HRC installation groundwater conditions. After application of the HRC, samples can be collected every other month for a six to eight month period. After the initial biodegradation and geochemical trends have been identified, the monitoring frequency can be decreased to a quarterly, semiannual, or annual program.

The monitoring protocol should call for standard low flow groundwater sampling techniques and include the measurement of the following field/chemical parameters:

• All relevant contaminants
• Field parameters: DO, ORP, pH, temperature, and ferrous iron (optional field measurement)
• Natural attenuation/inorganic parameters: dissolved iron and manganese, nitrate, sulfate, sulfide, chloride, and alkalinity
• HRC-based electron donor:total organic carbon and metabolic acids (lactic, pyruvic, acetic, propionic, and butyric)
• End-product dissolved gases: carbon dioxide, methane, ethane and ethene

A specially qualified laboratory should do the analytical testing for the metabolic acids, otherwise most laboratories can provide testing for the remaining parameters. A typical cost for the above testing program is approximately $300 per sample.