Groundwater Professional Bulletin Board

The requirement for sampling drinking water wells (DWWs) and nondrinking water wells (NDWWs) during a normal Tier 2 evaluation of the Groundwater Ingestion Pathway was inadvertently left out of the regulations and guidance. In keeping with the procedures applied to Plastic Water Line receptors, we provide the following guidance:

All existing drinking water wells (DWWs) and nondrinking water wells (NDWWs)within 100 feet of the largest actual plume (defined to the appropriate target level for the receptor type) must be tested for chemicals of concern. Actual plumes refer to groundwater plumes for all chemicals of concern.

Untreated, or raw water should be collected for analysis.

Laboratory data sheets must be submitted and sample results included in the Groundwater Analytical Data Table. These results should be ignored when performing the pathway evaluation in the software for a normal Tier 2 assessment (i.e., non-bedrock site; results are considered for bedrock pathway evaluations). Additionally, the owners of DWWs and NDWWs must be listed in the Groundwater Well Survey Table and Affected Property Owner Table.

As part of annual site monitoring, any DWWs and NDWWs within an actual plume defined to the appropriate target level (e.g., 5 PPB actual benzene plume for DWWs, and 290 PPB actual benzene plume for NDWWs), must be sampled for chemical of concerns.

NOTE: if elevated contaminant levels are detected in the water samples, the following must be notified immediately:

• DNR in all cases.
• Water supplier (public water systems).
• Local health department (private water supply).
• Well owner (private water supply).

Please contact Elaine Douskey at (515)281-8011 or elaine.douskey@dnr.state.ia.us if you have questions about this posting.