This section provides specific guidance pertaining to site assessment practices which should be utilized in conducting the BASA.

The BASA shall include the following:

  1. Obtain or evaluate records providing information about environmental conditions at the Dispensing Facility. Analyze and interpret information in the records for the potential presence of Petroleum Products and OHM at the Dispensing Facility;

  2. Evaluation of existing or former Underground Storage Tank System(s) to evaluate the potential of the UST System as a source of petroleum contamination to environmental media;

  3. Site reconnaissance and sampling to observe and measure environmental conditions at the Dispensing Facility;

  4. Interviews to obtain information about the site which has not necessarily been documented in records for the Dispensing Facility to guide the site reconnaissance and soil and groundwater sampling efforts; and,

  5. Report preparation to summarize the findings of the site assessment.

Records Review

The purpose of the records review is to obtain and evaluate existing documentation to assess existing environmental conditions at the Dispensing Facility. The environmental professional performing the records review must make a reasonable effort to obtain all documentation which is pertinent to assessing the environmental conditions at the Dispensing Facility including: (1) information which is publicly available, and (2) information available from the current and/or past owner/operator of the Dispensing Facility.

Publicly Available Information

The publicly available sources which should be reviewed and summarized in the BASA Report are shown on Table 1. In addition, local records which are reasonably obtainable should also be evaluated and records reviewed, in order to obtain additional information which is pertinent to assessing environmental conditions at the Dispensing Facility.

In addition to the sources shown in Table 1, the BASA should provide a discussion of the physical setting of the Dispensing Facility. A current USGS 7.5 Minute Topographic Map showing the area on which the Dispensing Facility is located, and a Massachusetts GIS DEP MCP (21E) Numerical Ranking System (NRS) Site Map of the site, must be provided in the report.

Historical records pertaining to the Dispensing Facility should also be obtained and reviewed as these records may contain pertinent data about the use and/or disposal of oil and/or hazardous materials at the Dispensing Facility. Historical records may also contain important information about the history of the previous uses or occupancies of the Dispensing Facility. The types of historical information which should be included as part of the BASA are shown in Table 2.

Historical information may be obtained from the sources shown in Table 1, and including but not limited to: (1) aerial photographs, (2) fire insurance maps, (3) property tax files, (4) recorded land title records, (5) USGS maps, (6) local street directories and maps, (7) records maintained by the local building department, and (8) zoning/land use records. In addition, previous environmental site assessment reports, if available, can be relied upon to provide historical information about the Dispensing Facility if such information is considered to be reasonably complete and accurate. However, historical usage of the Dispensing Facility subsequent to any previous site investigation report must be obtained and included in the BASA Report.

Information Obtained from Files Maintained by the Current and/or Past Owner/Operator

Pertinent information about the Dispensing Facility and its operation concerning environmental conditions that may not be available in public records should also be obtained from files maintained by the current and/or past owners and operators of the Dispensing Facility. This information may be obtained from the Dispensing Facility files and by conducting interviews with current and/or past owner/operators (see section 2.40). Pertinent information in the Dispensing Facility files pertaining to environmental conditions may include but is not limited to: (1) plans depicting locations of buildings, underground utilities, USTs, septic fields, oil/water separator(s), (2) permits, licenses, registrations, (3) inspection reports, (4) internal audit reports, and (5) incident reports.

Site Reconnaissance and Sampling

The extent of site reconnaissance and sampling activities should be conducted commensurate with the findings of the records review (section 2.20) and evaluation of existing Underground Storage Tank System(s) required by the Application for Certificate of Compliance for Dispensing Facilities.

Site Reconnaissance

The objective of the site reconnaissance is to take actual observations of site features and activities which are pertinent to assessing the environmental conditions of the Dispensing Facility. The environmental professional preparing the BASA is required to visit the Dispensing Facility at lease one (1) time to visually and physically observe the property and any structure(s) located on the property to the extent practicable. Reconnaissance of both the exterior of the Dispensing Facility as well as the interior of structures located on the Dispensing Facility should be conducted and documented in field notes which are to be appended to the BASA Report. The components shown in Table 3 should be included as part of the site reconnaissance.

The site reconnaissance field notes should include a sketch of the Dispensing Facility and adjacent properties as described in Table 4.

Field notes taken during the site reconnaissance must be signed and dated by the environmental professional conducting the reconnaissance.

Site Sampling

Site sampling activities are required for all BASAs in order to confirm the presence or absence of concentrations of Petroleum Products and OHM which require notification to DEP and which require a Response Action, excluding LRAs.

Soil and Groundwater Sample Collection and Analyses

Collection of soil and groundwater samples is required as part of the site investigation activities being conducted during a BASA.

Soil and groundwater sample collection should be performed at appropriate locations and using applicable methodology selected by a qualified environmental professional. Either temporary or permanent monitoring points may be employed. Appendix 3 of the 21J Regulations provides a list of references which contain guidance for the collection and analysis of soil and groundwater samples.

A minimum of one upgradient and three downgradient permanent groundwater sampling points must be installed on the property. The locations will be based upon records review, site reconnaissance, UST evaluation or interviews, if available, which indicate the potential for contamination at the Dispensing Facility, or property. In addition, one monitoring well shall be located in the approximate center of the area where known or former USTs were located, if feasible. The direction of groundwater flow can be initially evaluated based on existing site and/or regional data or inferred from local topography and hydrology to locate temporary or permanent monitoring points. Actual gauging data should be presented and evaluated to confirm groundwater flow direction. If necessary, additional monitoring wells should be installed to meet the requirements of having one upgradient and three downgradient monitoring well locations.

Existing tank field monitoring wells may also be used to satisfy groundwater monitoring requirements in the vicinity of an UST system, provided they are properly installed (see "Standard Reference for Monitoring Wells"; DEP Publication #WSC-310-91 and any updates) and are screened above and below the water table. In such case, a minimum of four tank field monitoring wells located in each corner of the tank field are required. Tank field monitoring wells should not be used to evaluate groundwater flow direction since such wells are typically installed in tank field backfill which is not representative of native soil conditions and there likely is not sufficient variation.

A site map drawn to scale depicting the locations of the permanent sampling points must be included in the BASA Report. Groundwater samples must be collected from each of the required sampling locations and analyzed to assess for the potential presence of Petroleum Product (see 503 CMR 2.02) constituents. For newly installed monitoring points, one soil sample per borehole must also be analyzed. The soil sample from each borehole with the highest field screening concentration of volatile organic compounds should be selected for laboratory analysis. Additional analyses for non-petroleum constituents must also be conducted if records review or other evidence exists which indicate the possible release of such constituents. Analytical methods suitable for identifying petroleum constituents include but are not limited to: EPA methods 6010/7000, 624, 8260, 602, 8020, 8015, 8100, 625, 8270, 524, and 525; and the DEP methods for volatile petroleum hydrocarbons (VPH) and extractable petroleum hydrocarbons (EPH). Surrogate analyses such as total petroleum hydrocarbon (TPH) using either GC/FID or IR techniques may also be employed. At a minimum, the following analyses shall be performed on at least one soil and one groundwater sample from each of the required monitoring points pursuant to this section: US EPA Method 200/6000/7000 series for Priority Pollutant 13 Metals (AS/SB/BE/CD/CR/CU/NI/PB/HG/SE/AG/TL/ZN); US EPA method 8260; and, the DEP Methods for VPH and EPH.


The purpose of conducting interviews with current and/or past owners and/or operators of the Dispensing Facility is to obtain additional information about potential releases which may have occurred at the Dispensing Facility which are not necessarily well documented and to gather more specific data about historical operations at the site. Interviews can be conducted by phone or in writing, although interviews conducted in person generally result in more thorough information exchange. Interviews may be conducted either before, during, or after the site reconnaissance. At a minimum one interview with the current owner or operator of the Dispensing Facility prior to conducting the Site Reconnaissance per Section 2.30.1 shall be performed. Ideally the interview should be conducted with someone who is knowledgeable about current and historical operations at the Dispensing Facility including the current and historical UST systems. Interviews with prior owners or operators are encouraged although not required. Guidance on the types of questions that should be asked during the interview are provided in Table 5.


The BASA Report should be presented in the format shown in Table 6. The report must include a summary and conclusions section which provides one of the following two conclusions:

  1. Based upon the records review, interviews, site reconnaissance, and site sampling activities, there are no levels of Petroleum Products, or conditions related to a release of Petroleum Products which require notification to DEP and which require a Response Action, excluding LRAs; or

  1. Based upon the records review, interviews, site reconnaissance, and site sampling activities, there are levels of Petroleum Products, or conditions related to a release of Petroleum Products which require notification to DEP and which require a Response Action, excluding LRAs.

The summary and conclusions section can provide additional language to qualify the basis for the stated conclusion and provide more specific details about the types of information which were used in reaching the stated conclusion.

The BASA must be signed by a Massachusetts Licensed Site Professional and contain the following opinion in the format shown:


I attest under the pains and penalty of perjury that I have personally examined and am familiar with this submittal, including any and all documents accompanying this submittal. In my professional opinion and judgement, I further declare under the penalty of perjury that to the best of my knowledge and belief the statements made and information provided in this submittal are true and that the submittal meets the minimum requirements for a BASA based upon the application of 503 CMR 2.02 Definitions, BASA and Policy # UST-21J-001.

Release Tracking Number: ________-________________________(if applicable)

LSP Name:_________________________________________ Title:__________________________

LSP Number:_______________________________________

LSP Organization:___________________________________