(1) Purpose. The purpose and intent of this section is to safeguard groundwater resources within the shoreline jurisdiction from hazardous substance and hazardous waste pollution by controlling or abating future pollution from new land uses or activities.
(2) Aquifer Recharge Area Designation Criteria.
(a) Aquifer recharge areas shall be classified as follows:
Aquifer Recharge Area Characteristic/Designation
(1) Wellhead protection areas pursuant to Chapter 246-290 WAC
WA Department of Health, US Environmental Protection Agency
(3) Areas overlying unprotected aquifers. Such aquifers shall be identified through any existing competent hydrogeologic study
(4) Areas within identified unprotected aquifers but possessing the following characteristics:
• Slopes less than 15 percent
• Coarse alluvium or sand and gravel in the soil profile and no known impermeable layers
(b) Any project area located within 200 feet of an area meeting the aquifer designation or soil classification criteria, or mapped as such, shall be treated as if it is located within the mapped area.
(c) All areas within the City of Pasco meeting these criteria, regardless of the presence or lack of any formal identification as such, are hereby designated as critical areas and are subject to the provisions of this title.
(3) Aquifer Recharge Area Classification.
(a) Aquifer recharge areas are classified as high, moderate, or low significance aquifer recharge areas according to the following criteria:
Documentation and Data Sources
High significance aquifer recharge areas are areas with slopes of less than 15 percent underlain by coarse alluvium or sand and gravel
Moderate significance aquifer recharge areas are:
(1) Areas with slopes of less than 15 percent underlain by fine alluvium, silt, clay, glacial till, or deposits from the Electron Mudflow
(2) Areas with slopes of 15 percent to 30 percent underlain by sand and gravel
Moderate significance aquifer recharge areas are:
(1) Areas with slopes of 15 percent to 30 percent underlain by silt, clay, or glacial till
(2) Areas with slopes greater than 30 percent
(4) Determination of Need for Aquifer Recharge Detailed Study.
(a) The following information resources shall be utilized along with other documentation where noted:
(i) Studies from the USGS;
(ii) City of Pasco wastewater facility plan;
(iii) Soil Survey for Franklin Conservation District.
(b) Requirements for High Significance Aquifer Recharge Area. An aquifer recharge area detailed study shall be required for any activity occurring on or adjacent to a site that is, or contains, a high significance aquifer recharge area if the activity involves one or more of the following uses:
(i) Hazardous substance processing or handling;
(ii) Hazardous waste treatment and storage facility;
(iii) Disposal of on-site sewage for subdivisions, short plats, and commercial and industrial sites; or
(5) Aquifer Recharge Area Detailed Study. When required as described in subsection (4) of this section, an aquifer recharge area detailed study shall meet the following requirements:
(a) The detailed study shall be prepared by qualified consultant with experience in preparing hydrogeologic assessments. Evidence of these qualifications shall be provided with the detailed study.
(b) The detailed study shall contain a map, of a scale no smaller than one inch equals 200 feet, of the site and the extent of the high significance aquifer recharge area as determined by the criteria in subsection (2) of this section.
(c) The detailed study shall contain a hydrogeologic assessment, including, at a minimum:
(i) Information sources;
(ii) Geologic setting;
(iii) Background water quality;
(iv) Location of, and depth to, water tables;
(v) Recharge potential of the facility site;
(vi) Groundwater flow direction and gradient;
(vii) Currently available data on wells within 1,000 feet of the site;
(viii) Currently available data on springs within 1,000 feet of the site;
(ix) Surface water location and recharge potential;
(x) Water source supply to the activity (e.g., high capacity well);
(xi) Any sampling schedules necessary;
(xii) Discussion of the effects of the proposed project on the groundwater resource; and
(xiii) Other information as may be required by the City.
(d) The detailed study shall include a mitigation plan detailing how the activity will offset any impact on the resource and control risk of contamination to the aquifer.
(6) Aquifer Recharge Area Detailed Study Special Exemptions. In addition to the exemptions listed in PMC 29.25.020(3) and 29.35.080, Exemptions for shoreline substantial development permits, sewer lines and appurtenances shall be exempt from the requirement to prepare an aquifer recharge area detailed study.
(7) Performance Standards Basic Requirements.
(a) Any activity listed in PMC 29.25.050(4)(b) may only be permitted in a high significance aquifer recharge area if the detailed study documents that the activity does not pose a threat to the aquifer system and the proposed activity will not cause contaminants to enter the aquifer.
(b) All activities located in an aquifer recharge area shall minimize the creation of impervious surfaces to the extent practicable without creating a greater risk to the aquifer recharge area.
(8) Storage Tanks. All Storage tanks located in an aquifer recharge area must conform to the following requirements. Ecology also regulates and authorizes permits for underground storage tanks (Chapter 173-360 WAC).
(a) Underground Tanks. All new underground storage facilities used or to be used for the underground storage of hazardous substances or hazardous wastes shall be designed and constructed so as to:
(i) Prevent releases due to corrosion or structural failure for the operational life of the tank;
(ii) Be protected against corrosion, constructed of noncorrosive material, steel clad with a noncorrosive material, or designed to include a secondary containment system to prevent the release or threatened release of any stored substances; and,
(iii) Use material in the construction or lining of the tank that is compatible with the substance to be stored.
(b) Aboveground Tanks.
(i) No new aboveground storage facility or part thereof shall be fabricated, constructed, installed, used, or maintained in any manner which may allow the release of a hazardous substance to the soil, groundwater, or surface waters within an aquifer recharge area.
(ii) No new aboveground tank or part thereof shall be fabricated, constructed, installed, used, or maintained without having constructed around or under it an impervious containment area enclosing or underlying the tank or part thereof.
(iii) New aboveground tanks will require a secondary containment system, either built into the tank structure or a dike system built outside the tank, for all tanks located within an aquifer recharge area. [Ord. 4314 § 2, 2016; Code 1970 § 29.01.540.]