The state of Washington department of ecology pursuant to RCW 90.48.035, 90.48.270, and 90.48.280 hereby adopts and promulgates these rules and regulations for the development, submission, and adoption of water pollution control and abatement plans for sewage drainage basins.

The rules and regulations of the department of ecology contained herein set forth the procedures necessary to conform with RCW 90.48.280 and 90.48.290(3). Ecology's review must primarily assure that the plan provisions will give adequate protection to and preservation of present and future water quality as indicated in the water quality standards for interstate and intrastate waters as they now exist or may hereafter be amended.

(1) Basin - See "sewage drainage basin," subsection (17) of this section.

(2) Ecology - The state of Washington department of ecology.

(3) Construction plans and specifications - The final engineering design before construction of facilities. Construction plans and specifications shall include, where applicable, sewerage system plans, plans of sewage pumping stations, plans for wastewater treatment facilities, and complete technical specifications for construction as set forth in WAC 372-20-030, 372-20-040, 372-20-060, 372-20-070(2), and 372-20-100(2). Construction plans and specifications shall be prepared according to criteria developed and selected in the preliminary engineering report (subsection (14) of this section).

(4) Drainage basin - An area from which surface runoff is carried away by a single drainage system. Ecology has delineated sewage drainage basins as defined in subsection (17) of this section for the purpose of administering this long-range water pollution control and abatement planning program.

(5) Industrial wastes - The liquid, solid, or other wastes from industrial processes, as distinct from domestic or sanitary wastes. These wastes may result from any process of industry, manufacture, trade or business, or from the development of any natural resource.

(6) Interceptor or intercepting sewer - A sewer that receives domestic and industrial dry-weather flow from a number of transverse sewers or outlets and frequently additional predetermined quantities of stormwater (if from a combined system), and conducts such waters to a point for treatment and disposal.

(7) Interstate waters - The entire stretch within the state of Washington of all rivers, lakes, and other waters that flow across or form a part of the state or international boundaries anywhere along their length, including coastal waters. Coastal waters are further defined as the ocean waters along coasts, straight or indented, which are subject to the ebb and flow of the tides.

(8) Intrastate waters - The surface waters whose drainage basins are solely contained within the boundaries of the state of Washington and are not affected by tidal influence.

(9) Municipal wastewater - Basically domestic sewage but including sewage discharging from sanitary conveniences of office buildings, factories and institutions, and such industrial wastes as may be allowed by the municipal code.

(10) Planning agency - That organization approved or designated by ecology which has the responsibility and authority for preparing the basin plans as specified in WAC 372-68-060 and which will, where possible, implement the approved plans through its authority to finance, construct, and operate the necessary facilities.

(11) Planning area - A sewage drainage basin (subsection (17) of this section) or combinations thereof which have close geographic, political, or social ties.

(12) Planning guide - The document which specifies in detail the recommended and required content of a water pollution control and abatement plan for a sewage drainage basin. See WAC 372-68-040.

(13) Planning level - That point in the anticipated community growth for which needs and solutions are determined. Planning levels of either the present, 1980, 1990, and 2000 or the present, 1985, and 2000 are recommended.

(14) Preliminary engineering report - A thorough engineering study which develops a sound and economical plan for a particular sewerage and/or treatment facility project (or projects), provides methods of operation and maintenance of such facility, and sets forth the water quality and design criteria to be used in the preparation of construction plans and specifications according to WAC 372-20-005, 372-20-030, 372-20-040, 372-20-060, 372-20-070(1), and 372-20-100(1). Such preliminary engineering report should be developed within the framework of the water pollution control and abatement plan for that sewage drainage basin in which it is located.

(15) Service area - That area which is or can be served by a sewerage system. Future service areas should be determined according to population density and need with consideration being given to the basin approach.

(16) Sewage - See "wastewater," subsection (20) of this section.

(17) Sewage drainage basin - These basins are adopted under WAC 372-68-100. The boundaries of the basins are as shown on the attached map.

(18) Sewage drainage basin plan - See "water pollution control and abatement plan for sewage drainage basins," subsection (21) of this section.

(19) Sewer - A pipe or conduit that carries wastewater or drainage water.

(20) Wastewater - The spent water of a community. From the standpoint of source, it may be a combination of the liquid and water-carried wastes from residences, commercial buildings, industrial plants and institutions, together with any groundwater, surface water, and stormwater that may be present.

(21) Water pollution control and abatement plan for a sewage drainage basin - A plan which describes a drainage basin or portions thereof and provides for control and abatement of water pollution and the protection of water quality in such basin by a logical interim and long-range plan for approximately thirty years into the future. Such plans shall be developed according to WAC 372-68-060.

(22) Water resource inventory area (WRIA) - See "sewage drainage basin," subsection (17) of this section.

The "sewage drainage basin and urban area planning guide for water pollution control and abatement" contains recommendations and suggestions with respect to the development of such plans and is hereby approved by the state of Washington department of ecology. This guide should be used as the basis for the preparation of all water pollution control and abatement plans. Recent developments in the field of water quality should be incorporated into this guide.

(1) A plan will be prepared for each basin by the planning agencies having authority within that basin. Each agency will plan only for that area for which it has authority or for other areas by agreement.

(2) Within each basin a single agency or committee will be responsible for coordination of the water pollution control and abatement planning efforts. Where possible, such agency or committee will also be responsible for the preparation and implementation of the water pollution control and abatement plan.

(3) To facilitate covering a logical planning area, a single agency may be made responsible for more than one basin.

(4) A single planning document may be proposed in which more than one basin is included, providing the basins are clearly designated.

(5) Any municipality may prepare and submit a separate service area plan through the basin plan coordinating agency or committee to ecology.

(6) The basin plan-coordinating agency or committee should be agreed upon by, but not limited to, ecology and county, municipal, metropolitan, regional and special purpose agencies having authority within the basin.

(7) Such agreement will be formalized by contract as provided for in chapter 39.34 RCW, the Interlocal Cooperation Act, when legally possible.

(8) Ecology shall assume the responsibility for preparation and coordination of the sewage drainage basin plans or will designate a plan-coordinating agency from among those agencies having jurisdiction within the basin.

The water pollution control and abatement plan shall include but not be limited to:

(1) Introduction (includes statement of purpose and intent, acknowledgments, summary of findings, and base map).

(2) Basis for planning

(a) Physical environment

(i) Topography - General description

(ii) Soil and drainage characteristics - Adequate interpretation of soil types and surface grades to determine suitability for septic tank filter fields

(iii) Hydrology - A brief summary of stream discharge records to include maximum, mean and minimum annual flows and 7-day 10-year low-flow; areas where low-flow establishment is needed; where applicable, a brief summary of information pertaining to the water table and flood plains (100 year floods)

(iv) Water quality - A brief summary of available water quality data; classification by interstate and intrastate water quality standards

(v) This section is to include maps of topography, soil and drainage characteristics, flood plains, watercourse classification and water quality problem areas, and location of sampling stations for quantity and quality.

(b) Social and economic growth

(i) Economy - To include a brief summary of commerce and industrial development

(ii) Population - To include trends, projections, and population densities based on census tracts or their equivalent for each planning level

(iii) Land use and zoning - Based on (i) and (ii) above summarize existing and projected zoning and land use for each planning level

(iv) This section is to include maps of present and future land use and population densities

(3) Inventory of existing facilities and sources and characteristics of wastes

(a) Collection systems - To include the delineation of service areas, operating authorities, the general location and capacities of interceptors, adequacy of facilities, population served, industries served, major commercial complexes served, and combined storm-sanitary sewers; also to include the numbers and general locations of individual waste disposal facilities.

(b) Treatment facilities - To include, for municipal treatment plants and industrial wastewater discharges, locations of treatment facilities, volumes and characteristics of wastes treated, degree of treatment, and adequacy of facilities; also for municipal treatment facilities the operating authority should be specified.

(c) Other water quality considerations - To include discussion and location of other water quality effect sources including but not limited to:

(i) Municipal wastes

(ii) Industrial wastes

(iii) Individual sanitary discharges

(iv) Storm runoff

(v) Soil erosion and land development runoff

(vi) Agricultural waste water, including irrigation return flow and animal feedlot wastes

(vii) Wastes from vessels and marinas

(viii) River impoundments

(ix) Log storage, including cold decking and rafting

(x) Dredging and dredging spoils

(xi) Solid waste disposal runoff and seepage water

(d) This section to include maps showing the general location of service areas and interceptors, municipal and industrial treatment facilities, and "other" water quality problem areas.

(4) Present and future water pollution control needs

(a) Collection systems - To include specification of immediate needs and, for each future planning level, delineation of service areas, operating authorities, general location and capacities of interceptors, population, industries, and major commercial complexes served, combined storm-sanitary sewers to be replaced by separate sewers, approximate number of connections, and percent of homes within the service area to be served.

(b) Treatment plants - To include specification of immediate needs, and for each future planning level, general location of treatment facilities, volumes and characteristics of wastes treated, and degree of treatment for municipal and industrial wastewater discharges; also for municipal treatment facilities the operating authority should be specified.

(c) Other water quality considerations - To include means of alleviating other water quality problems which now exist and to prevent such deleterious effects in the future.

(d) Recommended legal considerations - List and explain policy statements, ordinances, and legislation to prevent future water quality deterioration.

(e) This section is to include maps showing future service areas, general locations and capacities of interceptors and municipal and industrial treatment plants, and "other" water quality problem areas.

(5) Plan considerations

(a) Collection systems and treatment plants - To include factors not included in the previous section which would affect the logical and orderly implementation of the plan. Such factors should include interim and alternate measures and the criteria to govern the extension of sewer lines.

(b) Other water quality considerations - To include consideration of other phases of environmental quality such as water supply, solid wastes management, and air pollution as they might be affected by the water pollution control and abatement plan.

(6) Capital improvements program

(a) Approximate construction schedule - To include scheduling of immediate need items including those listed in the implementation and enforcement plans for interstate and intrastate waters and for ten years beyond the plan completion date.

(b) Cost estimates and financing - To include general construction costs of the various elements of the plan and a brief evaluation of the sewer service charges and financial considerations necessary to finance needed construction.

(7) Format and updating

(a) This outline is not necessarily meant to be used as a pattern for the plan format. Provisions to review this plan every five years or more often as development warrants and to update as necessary will be included.

(b) Ecology will designate, prior to August 1, 1970, which state, regional and/or federal documents should be used as references in forecasting social and economic trends. Such documents will include, but not be limited to, resource development, land use proposals, demographic data, industrial growth, and financial forecast documents.

(1) Two copies of said water pollution control and abatement plan will be submitted to ecology for review. Within thirty days of receipt ecology will approve or reject said plan in writing. Upon ecology approval a public hearing will be scheduled for a date within thirty days of said approval. This hearing will be preceded by the appropriate notices as set forth in RCW 42.32.010. Such hearing may be continued from time to time, and at the termination thereof, ecology may reject the plan proposed or adopt it with such modifications as it shall deem proper. Said adoption will take place within sixty days of the termination of the hearing. One copy of the water pollution control and abatement plan adopted by ecology will be stamped with the approval stamp of ecology and returned to the agency which submitted said plan with instructions to notify all involved entities within fifteen days.

(2) Ecology will consider for adoption plans for sub-areas within a basin if it shall deem such adoption desirable or necessary to prevent undue delay in the construction of urgently needed water pollution control facilities. In all such cases the sub-area plan should be developed according to WAC 372-68-060 and should be submitted through the basin plan-coordinating agency if possible.

After a plan has been adopted, occasions may arise when a change in certain parts of the plan provisions is necessary. Proposed deviations from the adopted water pollution control and abatement plan which affect the adequacy and efficiency of plan provisions shall be submitted to ecology in duplicate. Such amendments will then follow the review, hearing, and adoption sequence specified in WAC 372-68-070.

(1) Ecology recognizes three basic phases of planning:

(a) Water pollution control and abatement plan (for sewage drainage basins)

(b) Preliminary engineering report

(c) Construction plans and specifications

(2) These phases are defined as given in WAC 372-68-030. The water pollution control and abatement plan, which covers all water pollution sources, is wider in scope than the other two phases, which deal primarily with the design and construction of wastewater collection and treatment works. The last two phases are progressively more detailed than is the water pollution control and abatement plan. Preliminary engineering reports for proposed wastewater collection and/or treatment facilities must comply with the water pollution control and abatement plan for the sewage drainage basin in which they are located. Construction plans and specifications for a proposed facility must comply with the preliminary engineering report for that facility.

(3) It is acceptable to combine the other phases of planning for proposed water pollution control facilities with the water pollution control and abatement plan subject to limitations as specified in WAC 372-20-030. Such a combined plan will receive as many certifications of approval as the phases of planning which it satisfied.

Ecology, pursuant to RCW 90.48.270 hereby adopts as sewage drainage basins the water resource inventory areas delineated as shown.