Owners and operators must ensure site assessments, including site checks, are performed in accordance with the requirements of this section.

1. (1) Applicability. Site assessments are required under this chapter to:

   1. (a) Investigate a suspected release from an UST system, as applicable (WAC 173-360A-0720(2)). Such assessments are referred to as "site checks";
   2. (b) Suspend financial responsibility for a temporarily closed UST system (WAC 173-360A-0800 (3)(c) and 173-360A-1010(2));
   3. (c) Allow an UST system to be temporarily closed for more than twelve months when the tanks or piping do not meet applicable performance standards or upgrade requirements (WAC 173-360A-0800(4));
   4. (d) Permanently close an UST system, or a tank or piping run that is part of an UST system (WAC 173-360A-0810(3)); and
   5. (e) Undertake a change-in-service of an UST system (WAC 173-360A-0820(3)).
2. (2) Service provider. Site assessments must be performed or directly supervised by a service provider certified in accordance with Part 9 of this chapter. The service provider must be present at the UST facility when and where the site assessment is performed and any tanks or piping are removed.

3. (3) Sampling and analysis plans. A sampling and analysis plan must be prepared for all sampling activities that are part of a site assessment.

   1. (a) Submission. The department may require a sampling and analysis plan be submitted to the department at least thirty days before any sampling is performed. The department may also require alternative sampling and analysis.

   2. (b) Content. A sampling and analysis plan must include the following information at a minimum:

      1. (i) The reasons for performing the site assessment;
      2. (ii) The UST system or portion of the UST system around which the assessment is to be performed;
      3. (iii) The media to be assessed, including under what circumstances groundwater will be assessed or an explanation of why groundwater does not need to be assessed;
      4. (iv) The number and location of samples to be collected. If the plan does not include all of the soil samples specified in subsection (5)(a)(i) of this section, then the plan must explain how physical conditions prevent the collection of those samples;
      5. (v) The methods to be used to collect and handle the samples;
      6. (vi) The regulated substances to be analyzed for in the samples;
      7. (vii) The methods to be used to analyze the samples for those substances;
      8. (viii) The name of the accredited laboratory to be used to perform those analyses;
      9. (ix) The methods to be used for quality assurance and quality control; and
      10. (x) Any other information required by the department.
4. (4) Health and safety requirements. Persons performing site assessments under this chapter must comply, as applicable, with the requirements of the Occupational Safety and Health Act (20 U.S.C. Sec. 651 et seq.) and the Washington Industrial Safety and Health Act (chapter 49.17 RCW), and regulations promulgated pursuant thereto. These requirements are subject to enforcement by the designated federal and state agencies.

5. (5) Sampling and analysis requirements. Site assessments must be performed in accordance with the requirements of this subsection, except as otherwise directed by the department. The department may require additional sampling or analysis on a site-specific basis to confirm whether a release has occurred that may pose a threat to human health or the environment or to address any such threats.

   1. (a) Soil assessment.

      1. (i) Number and location of samples. Soil samples must be collected where contamination has been detected or is most likely to be present. At a minimum, the soil samples specified in Table 0730-1 must be collected unless:

         1. (A) Physical conditions prevent the collection of any of the specified samples and an alternative sampling plan is prepared. The department must be notified in the site assessment report of any such changes and the reasons for the changes; or
         2. (B) A release that may pose a threat to human health or the environment is confirmed without the collection of some or all of the specified samples.

      2. (ii) Regulated substances to be analyzed. All regulated substances currently or previously stored in the UST system must be analyzed for in the soil samples.

         1. (A) For petroleum, analyze for the substances specified for the type of product in Table 830-1 of WAC 173-340-900.
         2. (B) For hazardous substances, analyze for the substances and any likely decomposition by-products.
      3. (iii) Analytical procedures. The soil samples must be collected, handled, and analyzed in accordance with the requirements in WAC 173-340-830.

      4. (iv) Evaluation of results. A release that may pose a threat to human health or the environment is confirmed if the concentration of any regulated substance analyzed in any of the soil samples exceeds the following levels:

         1. (A) The level specified in Table 740-1 of WAC 173-340-900; or
         2. (B) If a regulated substance is not listed in Table 740-1, a Method B unrestricted soil cleanup level established under WAC 173-340-740(3).

   2. (b) Groundwater assessment.

      1. (i) Applicability. Groundwater must be sampled if a release has not been confirmed by soil sampling and if:

         1. (A) The lowest point of the UST system is located in groundwater;
         2. (B) A release is suspected based on environmental contamination and the lowest point of the UST system is located within two feet of the seasonal high water table;
         3. (C) Groundwater monitoring wells already exist at the UST facility where the site assessment is being performed, the wells are located in areas at the facility that would provide useful data, and the condition of the wells allows for the collection of representative samples;
         4. (D) Physical conditions prevent collection of all or some of the soil samples required under (a)(i) of this subsection and groundwater sampling is part of an alternative sampling plan; or
         5. (E) Groundwater sampling is otherwise required by the department.
      2. (ii) Number and location of samples. Groundwater samples must be collected where contamination has been detected or is most likely to be present.

      3. (iii) Regulated substances to be analyzed. All regulated substances currently or previously stored in the UST system must be analyzed for in the groundwater samples.

         1. (A) For petroleum, analyze for the substances specified for the type of product in Table 830-1 of WAC 173-340-900.
         2. (B) For hazardous substances, analyze for the substances and any likely decomposition by-products.
      4. (iv) Analytical procedures. The groundwater samples must be collected, handled, and analyzed in accordance with the requirements in WAC 173-340-830.

      5. (v) Evaluation of results. A release that may pose a threat to human health or the environment is confirmed if the concentration of any regulated substance tested in any of the groundwater samples exceeds the following levels:

         1. (A) The levels specified in Table 720-1 of WAC 173-340-900; or
         2. (B) If the regulated substance is not listed in Table 720-1, a Method B potable groundwater cleanup level established under WAC 173-340-720(4).

6. (6) Reporting and cleanup of confirmed releases. If a site assessment confirms that a release has occurred from an UST system that may pose a threat to human health or the environment, then:

   1. (a) The service provider who performed or directly supervised the site assessment must notify:

      1. (i) An owner or operator of the UST system immediately; and
      2. (ii) The department within twenty-four hours. However, if an owner or operator of the system is not immediately available, the service provider must notify the department immediately.
   2. (b) Owners and operators must report, investigate, and clean up the confirmed release in accordance with WAC 173-360A-0750.

7. (7) Reporting results of assessment.

   1. (a) Site assessments must be reported to the department within thirty days by submitting the applicable checklist provided by the department and a report including the information specified in subsection (8) of this section. Both the checklist and the report must be completed by the service provider.
   2. (b) If a site assessment confirms a release that may pose a threat to human health or the environment, the site assessment report may be combined with the remedial action reports required under WAC 173-340-450, provided the combined report is submitted within thirty days of release confirmation.

8. (8) Content of report. At a minimum, site assessment reports must include the following information:

   1. (a) Information about the service provider who performed or directly supervised the site assessment, including the name of the service provider, the certification type and number, and the firm with which the service provider is affiliated;

   2. (b) Information about the UST system and the UST facility where the system is located, including:

      1. (i) The name of the owner and operator of the system and the owner of the property where the system is located, if different;
      2. (ii) The location of the system within the facility;
      3. (iii) The components comprising the system;
      4. (iv) Any previous repairs to the system;
      5. (v) The type of regulated substances stored in the system, both currently and historically since the date of installation;
      6. (vi) The dimensions of the excavation zone and the depth, width, and type of backfill material used within that zone, if known;
      7. (vii) The number and location of any other currently or previously regulated systems at the facility; and
      8. (viii) The types and locations of any groundwater monitoring wells at the facility;
   3. (c) Information on any previous leaks or confirmed releases from the UST system, and whether the releases were cleaned up;

   4. (d) The physical characteristics of the UST facility, including the following:

      1. (i) The current uses of the land within and adjacent to the facility, and any known prior uses of that land;
      2. (ii) The geology of the site, including soil types and characteristics;

      3. (iii) The hydrology of the site, including:

         1. (A) Surface draining characteristics;
         2. (B) Depth to groundwater (including seasonal fluctuations);
         3. (C) Presence of groundwater in the excavation zone, direction of groundwater flow (if relevant to any groundwater sampling plan);
         4. (D) Proximity of the UST system to any nearby drinking water wells or surface water bodies (if known); and
         5. (E) Potential hydraulic connections between groundwater and any nearby surface water bodies (if known); and
      4. (iv) The location of tax parcel(s) comprising the facility, any above-ground and below-ground structures at the facility, any paved areas at the facility, and any roads or utilities on or adjacent to the facility;
   5. (e) A summary of the sampling and analyses performed, including any changes to the plan or the sampling or analyses required under this section and the reason for those changes;
   6. (f) All laboratory reports;

   7. (g) The results of the site assessment, including:

      1. (i) A table showing, for each field sample collected, the unique identifying number assigned to the sample, whether the sample was a composite sample, the laboratory results for all indicator constituents analyzed, the method used to analyze the sample, and the detection limit for that method;
      2. (ii) Any factors that may have compromised the quality of the data or validity of the results; and
      3. (iii) A conclusion as to whether there has been a release of regulated substances from the UST system that may pose a threat to human health or the environment;
   8. (h) Site diagrams that include the following information at a minimum:
   9. (i) The geographic location of the UST facility and a north arrow;
   10. (ii) The location of the UST system within the UST facility, including the location of all tanks, piping, and dispensers, and any adjacent structures or streets;
   11. (iii) To the extent known, the dimensions of the excavation zone and the backfill material used within that zone;
   12. (iv) The physical characteristics of the UST facility, including the information specified in (d) of this subsection and the location of any other regulated UST systems at the facility; and
   13. (v) The horizontal and vertical location of and unique identifying number for all samples collected for laboratory analysis, and which samples were collected from excavated soils. Diagrams must clearly differentiate between soil and groundwater samples and between investigatory and confirmation samples; and
   14. (i) Any other information required by the department.

9. (9) Department determination. After receiving a site assessment report, the department will determine whether any further assessment or information is necessary. The department may require further sampling or analysis if:

   1. (a) The assessment performed does not comply with the requirements of this section; or
   2. (b) The department determines further assessment is necessary to confirm a suspected release, determine whether a release poses a threat to human health or the environment, or to address any such threats.

10. (10) Recordkeeping. Records of site assessments, including sampling and analysis plans and site assessment reports and checklists, must be maintained until six years after the UST system is permanently closed or undergoes a change-in-service.

    Table 0730-1: Minimum Number and Location of Soil Samples

    	Tanks	Piping	Dispensers
    In Place	Collect the following samples around the excavation zone where contamination is most likely to be present:	Collect one sample for every 50 feet of piping. For example, collect one sample if the piping run is less than 50 feet and two samples if the piping run is 50 to 100 feet. Collect the samples adjacent to the piping where contamination is most likely to be present, such as at connections, fittings, or elbows. (1, 2)	Collect one sample adjacent to each dispenser.(1, 2)
    • When assessing single tank with a capacity of < 9,000 gallons, collect three samples, one at each end and one on another side of the tank. (1, 2)
    • When assessing single tank with a capacity of ≥ 9,000 gallons, collect four samples, one at each side of the tank. (1, 2)
    • When assessing multiple tanks in an excavation zone, collect four samples for the first tank and two additional samples for each additional tank, spacing the samples evenly around the excavation zone. (1, 2)
    Removed	Collect the following samples within the excavation zone where contamination is most likely to be present:	Collect one sample for every 50 feet of piping. For example, collect one sample if the piping run is less than 50 feet and two samples if the piping run is 50 to 100 feet. Collect the samples beneath the piping where contamination is most likely to be present, such as at connections, fittings, or elbows. (2)	Collect one sample beneath each dispenser. (2)
    • When assessing single tank with a capacity of < 9,000 gallons, collect three samples, one beneath the tank (2), one beneath where the piping from the tank entered a sidewall, and one from another sidewall.
    • When assessing single tank with a capacity of ≥ 9,000 gallons, collect five samples, one from beneath the tank (2), one beneath where the piping from the tank entered a sidewall, and one from each of the other three sidewalls.
    • When assessing multiple tanks from an excavation zone, collect five samples for the first tank and two additional samples for each additional tank, one beneath each tank (2), one beneath where piping from each tank entered a sidewall, and spacing remaining samples evenly around the sidewalls.
    Collect the following samples from excavated soils where contamination is most likely to be present:
    Cubic Yards of Soil	Minimum Number of Samples
    0-25	1
    26-50	2
    51-100	3
    101-500	5
    501-1000	7
    1001-2000	10
    >2000	10 + 1 additional sample for each additional 500 cubic yards of soil

    Footnotes:	(1) Horizontal distance: The specified samples must be collected from native soil as close as practicable to, but no more than ten feet from the applicable tank, pipe, or dispenser.
    	(2) Vertical distance: The specified samples must be collected from native soil as close as practicable to the bottom of the applicable tank, pipe, or dispenser. If groundwater is encountered, soil samples must be collected at the approximate top of the water table.

[Statutory Authority: Chapter 90.76 RCW. WSR 18-15-083 (Order 16-02), § 173-360A-0730, filed 7/18/18, effective 10/1/18.]