Code of Maine Rules
06 - DEPARTMENT OF ENVIRONMENTAL PROTECTION
096 - DEPARTMENT OF ENVIRONMENTAL PROTECTION - GENERAL
Chapter 695 - RULES FOR UNDERGROUND HAZARDOUS SUBSTANCE STORAGE FACILITIES
Appendix 096-695-G - Minimum Standards for Site Assessments

1. The site assessment shall be supervised by, and site assessment reports shall be certified by, an independent Maine Certified Geologist.

2. The site shall be sampled in sufficient density for substances which singly or in combination will indicate the presence of all known hazardous substances stored during the operational life of the tank or facility except for those substances which were assessed during a previous site assessment meeting the requirements of this rule and have not since been stored in the facility. A statistically significant sampling program acceptable to the Department must be completed to show that a site is not contaminated.

3. For tank removals the site assessment shall include a thorough visual inspection of the tank exterior for leaks, inspection of the open excavation for physical evidence of a leak, and soil gas screening if appropriate for the hazardous substance stored.

4. The site to be assessed shall be sampled in the areas where contamination is most likely to be present. If contamination is identified during a tank or facility closure, the site investigated shall extend beyond the known contaminated area to include the surrounding area possibly affected by the contamination. If environmental evidence of a leak is present on or off site the area investigated must extend beyond the location of the environmental evidence to include the surrounding area possibly affected by the contamination. If a site assessment is required due to confirmation of a leak without environmental evidence the site shall be sampled where contamination from the leak is most likely to be present.

5. Acceptable sampling methods include soil gas sampling; direct sampling of groundwater, backfill, and native geological materials; and alternative methods acceptable to the Department. If direct sampling methods are used the assessment should include below surface sampling of backfill and native geologic materials sufficient to detect vertical and lateral migration of contaminants. Sampling methods must be appropriate for the parameters being analyzed for, and the parameters being analyzed for must be appropriate for the hazardous substances stored. Sampling methods must also be appropriate for the hydrogeologic conditions at the site.

6. Samples shall be acquired, prepared, preserved, stored. transported, and analyzed by methods that will maintain sample integrity and meet analytical detection limits sufficient to determine the risk to public health and the environment.

7. If contamination is present the site assessment shall quantify and delineate the extent of free product and contaminated backfill, soils, surficial materials, bedrock and groundwater.

8. If contamination is present the site assessment shall include determination of the depth to water table and direction of groundwater flow.

9. If contamination is present the site assessment report shall describe soil, surficial materials, bedrock geology, hydrogeology and climate of the site. The site assessment shall also describe potential pathways for contaminant movement including sewer and utility lines.

10. If contamination is present the site assessment shall discuss the toxicity, mobility, and persistence of contaminants in relation to the hydrogeology of the site and in relation to potentially affected receptors.

11. If contamination is present the site assessment shall locate and describe potential receptors of contamination and shall describe the proximity of the contamination to private and public drinking water supplies, surface water bodies, and populated areas. The site assessment shall include a description of the classification under state and local classification systems, if any, of impacted or potentially impacted groundwater or surface water.

12. The site assessment report shall include specific recommendations for additional investigation and/or recommendations and rationales for site remediation including but not limited to free product removal, groundwater treatment, soil removal or treatment, control of vapors, surface water clean-up, or no action if justifiable by hydrogeologic, health, safety or other environmental criteria; descriptions of any remediation work completed or in progress; recommendations and rationales for further work or study as necessary; a map or drawing of the site showing components of the facility and sample locations; analytical results; data logs; a description of quality assurance/quality control procedures: and a summary of all work under taken as part of the site assessment including rationales for sample locations, sample parameters, and sampling methods.

13. A copy of the site assessment shall be sent to the department at the following address:

14. The Department reserves the right to reject unsatisfactory site assessments and require additional investigation, information and reporting. The Department also reserve the right to require, for Department review and approval, remedial action plans for cleanup of free product, contaminated soils and groundwater whenever it determines that sufficient data is available for remedial action design.

15. Nothing in this Appendix shall limit the Department's discretion or ability to order and/or undertake immediate remedial action at sites where evidence of contamination by a hazardous substance is present.

16. Determination of the action levels of hazardous substances that require remediation may be made by the Department on a case by case basis. At a minimum any concentrations of hazardous substances in the environment must be cleaned up to the extent necessary to protect human health. safety, and the environment.