WAC 173-350-330 - Surface impoundments and tanks

WAC 173-350-330 - Surface impoundments and tanks

Ecology staff lead: Bill Harris 

Work group members 

Focus: Section 330 regulates activities that are ancillary to primary functions of the solid waste system. It is explicitly applicable to facilities storing leachate from municipal solid waste landfills and limited purpose landfills, and surface impoundments associated with solid waste recycling and piles activities. 

There are several instances where other rules and other sections in this rule refer to part or all of the surface impoundment and tanks standards, making them applicable by reference. Section 330 does not specify which of its conditions should be applicable in the following cases: 

• Solid Waste Handling Standards - Beneficial Use Permit Exemptions, WAC 173-350-200. The general terms and conditions for beneficial use exemptions state that when a soil amendment is stored at an application site, it must not contain liquid waste unless the requirements of WAC 173-350-330 are met. 
• Solid Waste Handling Standards - Composting Facilities, WAC 173-350-220. The composting facility design criteria require that tanks used to store leachate at composting facilities must meet design standards in WAC 173-350-330(3)(b). 
• Solid Waste Handling Standards - Land Application, WAC 173-350-230. The operating criteria for facilities engaged in land application direct that the facility must be operated to ensure that storage of liquid waste or semisolid waste in surface impoundments or tanks meets the requirements of WAC 173-350-330. 
• Solid Waste Handling Standards - Anaerobic Digesters, WAC 173-350-250. The anaerobic digester standards identify WAC 173-350-330(3) as one of three sets of design standards that may be used for anaerobic digesters. 
• Biosolids Management - Requirements for facilities storing biosolids or sewage sludge, WAC 173-308-280. This section of the biosolids management rule states that certain facilities that store liquid biosolids or sewage sludge in surface impoundments must meet the requirements for the design, construction, and operation of surface impoundments in chapter 173-350 WAC. 

Issues to be addressed also include clarifying whether requirements of Section 330 are or should be applicable to storage of liquid or semi-liquid wastes that are being handled under a permit exemption by the provisions of the Solid Waste Handling Standards - Other organic material handling activities, WAC 173-350-225. 

The technical criteria of Section 330 for surface impoundments are similar to the criteria for wastewater lagoons described in Section G3-3.5 of Ecology's Water Quality Program Criteria for Sewage Works Design, but there are some distinct differences. The work group will look at clarifying the management of leachate generated at solid waste facilities that is being treated in surface impoundments for discharge under a water quality permit. It is unclear which criteria should apply to the impoundment/lagoon structures. 

Another issue to be explored is that there are no clear requirements for monitoring or reporting monitoring of leak detection systems in surface impoundments. There are no criteria for allowable leakage in primary or secondary impoundment liners, and hence no clear requirements to repair leaks that may be identified. There are no criteria for general maintenance of surface impoundments (for example, removal of sediment, debris, vegetation, etc.). 

Update: The work group began meeting in March 2015. Proposed changes are being evaluated but have not yet been shared with the workgroup. Please send questions to w2rrulemaking@ecy.wa.gov. 

Work group meetings and notes
March 19, 2015 9 a.m. - noon, Ecology Headquarters, Lacey 

• Final Meeting Notes - March 19, 2015