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Public Health Risks of Soil Contamination

The City of Wilmington found many hazardous substances posing risks to public health when they tested the soil at the Rodney Reservoir. According to a report the City published in October 2023: 

"Results of the risk calculation based on hazardous substances present indicated: 

  • Regulated substances in shallow soil pose an unacceptable cancer risk under the resident scenario.

  • Regulated substances in shallow and combined soil pose an unacceptable non-cancer risk under the resident child HI scenario."


(Rodney Reservoir Soil Sampling Report Prepared by Verdantis 10/10/2023)

Hazardous Substances Found at Rodney Reservoir

According to the City's October 12 report, "A total of 12 soil samples were collected at the Rodney Reservoir, comprised of one shallow soil sample and one deep soil sample from each of the six test pits." The following hazardous substances were found:

Delaware's Hazardous Substance Cleanup Act

Delaware’s Hazardous Substances Cleanup Act (HSCA) and DNREC regulations give DNREC two options:



Require the City to Clean Up the Site Before Starting Demolition

The City’s October report says that the hazardous materials in soils pose unacceptable cancer and non-cancer risks. Under state regulations, if an owner wants to disturb soils where hazardous substances pose unacceptable risks, the owner has to clean up the hazardous substances.


Here’s the DNREC regulation: 
“If the initial screening exceeds the acceptable risk, then the owner or operator must enter into a settlement agreement with DNREC-RS (Delaware Department of Natural Resources and Control- Remediation Section)and the facility will proceed through the HSCA (Hazardous Substances Cleanup Act) process to receive a COCR (Certificate of Completion of Remedy) under the VCP (Voluntary Clean-Up Program) or BDP (Brownfields Development Program.” (p. 7 “Hazardous Substance Cleanup Act Guidance for Notification Requirements”)


Allow the City to Leave the Site In Its Current Condition
According to the City’s soil testing report, hazardous materials in the soils at the Rodney Reservoir pose unacceptable risks for residential use but not for recreation, gardening, or visiting. State regulations give DNREC the option of allowing the City to leave the contamination in place, not disturb the soil, and file a deed restriction on the site to not allow residential development.


Here’s the DNREC regulation:
“If the preliminary risk assessment based on the representative supplemental data indicates an acceptable risk under the current conditions, then a CNFA (Conditional No Further Action Determination Process) can be issued if the current site conditions and any other restrictions imposed by the CNFA determination remain in place at the site.” (p. 4 Guidance for Conditional No Further Action Determination under Regulations Governing Hazardous Substance Cleanup )

DNREC Is Allowing the City to Demolish the Rodney Reservoir Before Cleaning Up Hazardous Substances

Despite the known contamination, here's all that DNREC is requiring from the City during demolition of the Rodney Reservoir:

  • “Soil disturbing activities at the Site should be conducted in accordance with DNREC’s generic Contaminated Materials Management Plan (CMMP, dated April 25, 2018); 

  • An Air Monitoring Work Plan should be developed and implemented during soil disturbing activities to monitor airborne particulate concentrations during demolition activities; and 

  • Following regrading and stabilization activities, additional soil sampling be completed to assess the final shallow soil conditions at the Site. Additionally, an updated risk assessment should be performed to confirm that the conclusions presented in this report remain valid.”  (DNREC-RS Approval of Supplemental Soil Sampling Report


These minimal requirements are not enough to protect the public health and are inconsistent with Delaware's Hazardous Substances Cleanup Act and related regulations.

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