Appendix A WAC 173-240-050 Department of Ecology Requirements for General Sewer Plans

WAC 173-240-050 (as of June 2013)

General Sewer Plan

1. All general sewer plans required of any governmental agency before providing sewer service are "plans" within the requirements of RCW 90.48.110. Three copies of the proposed general sewer plan and each amendment to it must be submitted to and approved by the department before implementing the plan.

2. The general sewer plan must be sufficiently complete so that engineering reports can be developed from it without substantial alterations of concept and basic considerations.

3. The general sewer plan shall include the following information together with any other relevant data as requested by the department. To satisfy the requirements of the local government jurisdiction, additional information may be necessary.

Where in Plan each subsection of Section 3 is addressed



Chapter(s) and/or Section in Plan


Purpose and need for the proposed plan.



Discussion of who will own, operate and maintain the systems.



Existing and proposed service boundaries.



Layout map to include the following (d.i-vii):



Boundary lines of the municipality or special district to be sewered, including vicinity map.

2.1, Appendix M


The location, size, slope, capacity, direction of flow of all existing trunk sewers, and the boundaries of the areas served by each.

Appendix M


The location, size, slope, capacity, direction of flow of all proposed trunk sewers, and the boundaries of the areas to be served by each.

10, Appendix M


The location of all existing and proposed pumping stations and force mains, showing which are existing and which are proposed.

10, Appendix M


Topography showing pertinent ground elevations and surface drainage, as well as proposed and existing streets.

Appendix M

Streams, lakes, and other bodies of water. The location and direction of flow of major streams, the high and low elevations of water surfaces at sewer outlets, and controlled overflows, if any. All existing and potential discharge locations should be noted.

2, Appendix M


Water systems. The location of wells or other sources of water supply, water storage reservoirs and treatment plants, and water transmission facilities.

2.7, Appendix M


The population trend and the estimated future population for the stated design period. Method used to determine future population trends and the concurrence of any applicable local or regional planning agencies.



Any existing domestic or industrial wastewater facilities within 20 miles of the general plan area and within the same topographical drainage basin containing the general plan area.

2, 3.6, Appendix M


A discussion of I/I, and actions that will alleviate these problems in the future.

5, 8.1


A statement regarding provisions for treatment and discussion of the adequacy of the treatment.

2.8, 3.6


List of industrial wastewater permittees, the quantity of wastewater and periods of production, and the character of the industrial wastewater insofar as it may affect the sewer system or treatment plant. Consideration must be given to future industrial expansion.



Discussion of the location of all existing private and public wells or other sources of water supply, and distribution structures as they are related to both existing and proposed domestic wastewater treatment facilities.

Not Applicable


Discussion of the various alternatives evaluated, and a determination of the alternative chosen, if applicable.



A discussion, including a table, that shows the cost per service in terms of both debt service and operation and maintenance costs, of all facilities (existing and proposed) during the planning period.

11, Appendix K


A statement regarding compliance with any adopted water quality management plan under the Federal Water Pollution Control Act as amended.

Not Applicable


A statement regarding compliance with the State Environmental Policy Act (SEPA) and the National Environmental Policy Act (NEPA), if applicable.

Appendix L