7 Del. Admin. Code § 1351-E-4.0

Current through Register Vol. 28, No. 7, January 1, 2025

Section 1351-E-4.0 - Hydrogeologic Investigation Requirements

4.1 General Requirement for Hydrogeologic Investigation

4.1.1 After a Release is confirmed and controlled, and LNAPL Corrective Action has commenced, Responsible Parties shall conduct a hydrogeologic investigation to determine the nature and extent of the Release and to make an initial estimate of any potential risks to human health, safety and to the environment, which are associated with the Release.

4.1.2 Responsible Parties shall conduct a hydrogeologic investigation to determine if an UST System is the source of environmental impacts to properties near an UST Facility. These impacts include the discovery of Regulated Substances such as the presence of LNAPL, dissolved phase contamination or vapors in soils, basements, sewer and utility lines, and nearby surface and drinking waters that have been observed by the Department or brought to its attention by another party.

4.2 Hydrogeologic Investigation Requirements

4.2.1 After a Release is confirmed, Responsible Parties shall conduct a hydrogeologic investigation in accordance with the requirements specified in the HIG as the first step in the Corrective Action process unless directed to do otherwise by the Department. The investigation shall at a minimum include the following:

4.2.1.1 Determine the nature of the Release, including the chemical compounds present, their concentrations, quantity released, and their physical and chemical characteristics related to potential human health and environmental impacts and cleanup procedures; and

4.2.1.2 Determine the extent of the Release, both horizontal and vertical, including whether the contaminant is distributed homogeneously or heterogeneously; and

4.2.1.3 Determine the physical characteristics of the site, including characteristics affecting the Occurrence, distribution, and movement of the released contaminant and characteristics affecting access to the site, both horizontal and vertical, which may influence the feasibility of various investigatory and remediation procedures; and

4.2.1.4 Evaluate, in accordance with the Delaware Risk-Based Corrective Action Protocol (DERBCAP) or other Department approved procedures, the potential risks posed by the Release including identification of environmentally sensitive receptors, and an estimate of the impacts to human health and the environment that may occur as a result of the Release.

4.2.2 Responsible Parties shall submit the results of the hydrogeologic investigation to the Department no later than 120 Days after a Release is confirmed or other Department approved schedule. The hydrogeologic investigation report shall include recommendations for further action or a request for a no further action determination in accordance with Part E, subsection 6.1.

4.2.3 The results of the hydrogeologic investigation shall be organized in report form in accordance with the requirements specified in the HIG and signed by a professional geologist or professional engineer registered in the State of Delaware as required in 24 Del.C. Ch. 36 and the Delaware Board of Registration of Geologists Regulations and 24 Del.C. Ch. 28.

4.2.4 The Department shall review the report and either accept the conclusions and recommendations of the report or require that within 90 Days or other Department approved schedule, the Responsible Parties shall submit additional information or a Remedial Action work plan (RAWP) to the Department.

4.2.5 The Responsible Parties may submit hydrogeologic investigation reports for a site separately or as part of a proposed long term Remedial Action work plan in accordance with the requirements of Part E, Section 5.0.

4.3 Quality Assurance and Quality Control Requirements

4.3.1 Responsible Parties shall develop and implement a site specific Quality Assurance/Quality Control (QA/QC) plan for the activities to be carried out during the hydrogeologic investigation and the QA/QC plan shall be included in the hydrogeologic investigation report submitted to the Department.

4.4 Site Safety Requirements

4.4.1 Responsible Parties shall develop a site specific health and safety plan which shall be furnished to the Department upon request and shall cover all hydrogeologic investigation tasks. The health and safety plan shall address the site worker protection levels, protection of Persons living near the site, and site access control during the investigation.

7 Del. Admin. Code § 1351-E-4.0

13 DE Reg. 1562 (06/01/10)
23 DE Reg. 581 (1/1/2020)
27 DE Reg. 533 (1/1/2024) (Final)