11/08/2016
Declarations of Compliance with PLANNING
Exception to Flow Control for the Riverview South Project. 2005 Stormwater Management Manual for Western Washington Prepared by John Bissell, AICP Principal Planner Lovell Sauerland Associates The applicant and the appellant’s engineers have reviewer the applicable stormwater manual and have found that the subject property should be exempt from stormwater flow control when the property develops. We believed this to be true because we believed from investigation and survey elevations that the ordinary high water (OHW) line of the Snohomish River reached Riverview Road. This document is intended as a declaration of compliance document. The City’s governing stormwater manual is the 2005 Stormwater Management Manual for Western Washington produced by the Washington State Department of Ecology. Exemptions from flow control are found in Volume I, section 2.5.7. The sections from the manual are copied verbatim. The applicant’s response provided a heading and the response is located in a bordered area to clearly separate the text from the manual from the responses. Volume I Section 2.5.7 Minimum Requirement #7: Flow Control Applicability Projects must provide flow control to reduce the impacts of stormwater runoff from impervious surfaces and land cover conversions. The requirement below applies to projects that discharge stormwater directly or indirectly through a conveyance system, into a fresh water ‐ except for projects that discharge to a water in Appendix I‐E ‐ Flow Control‐Exempt Receiving Waters in accordance with the following restrictions: Applicant’s response: The Snohomish River, downstream of confluence of Snoqualmie and Skykomish Rivers is listed in Appendix E, and therefore the Snohomish River is an Exempt Receiving Water. The edge of the river is defined as the Ordinary High Water (OHW) of the river (see bullet point 3 below). The Department of ecology and Hydrologist Ed … Have found the ordinary high water of the tidal zone to be located at Riverview Road. Therefore, undetained direct discharge of stormwater into the Exempt Receiving Water south of Riverview Road, west of the sewer treatment plant is permitted subject to the following criteria: •
Direct discharge to the exempt receiving water does not result in the diversion of drainage from any perennial stream classified as Types 1, 2, 3, or 4 in the State of Washington Interim Water Typing System, or Types “S”, “F”, or “Np” in the Permanent Water Typing System, or from any category I, II, or III wetland; and Applicant’s response: The applicant proposes to discharge stormwater in the same location that stormwater currently discharges from the site. No change in basin is proposed. •
Flow splitting devices or drainage BMP’s are applied to route natural runoff volumes from the project site to any downstream Type 5 stream or category IV wetland: Applicant’s response: Pre‐development stormwater currently flows to near the midpoint on the south property line of the subject property. That water is collected in a piped system that discharges directly to the ordinary high water of the Snohomish River. o
Design of flow splitting devices or drainage BMP’s will be based on continuous hydrologic modeling analysis. The design will assure that flows delivered to Type 5 stream reaches will approximate, but in no case exceed, durations ranging from 50% of the 2‐year to the 50‐year peak flow. Applicant’s response: N/A – no flow splitting is proposed. o
Flow splitting devices or drainage BMP’s that deliver flow to category IV wetlands will also be designed using continuous hydrologic modeling to preserve pre‐project wetland hydrologic conditions unless specifically waived or exempted by regulatory agencies with permitting jurisdiction; and Applicant’s response: N/A – no flow splitting is proposed. •
The project site must be drained by a conveyance system that is comprised entirely of manmade conveyance elements (e.g., pipes, ditches, outfall protection, etc.) and extends to the ordinary high water line of the exempt receiving water; and Applicant’s response: Pre‐development stormwater currently flows to near the midpoint on the south property line. That water is collected in a piped system that discharges directly to the ordinary high water of the Snohomish River. The applicant proposes to use that same piped system for discharging post development stormwater. •
The conveyance system between the project site and the exempt receiving water shall have sufficient hydraulic capacity to convey discharges from future build‐out conditions (under current zoning) of the site, and the existing condition from non‐project areas from which runoff is or will be collected; and Applicant’s response: The subject site is the only site that will develop using the piped system. The pipe system has been analyzed by a professional hydrologist ad has been found to have sufficient capacity. (see attaché hydrology report) •
Any erodible elements of the manmade conveyance system must be adequately stabilized to prevent erosion under the conditions noted above. Applicant’s response: The subject pipe system has no erodible portions with the possible exception of the outfall. If the outfall is substandard it will be repaired to meet standard. If the discharge is to a stream that leads to a wetland, or to a wetland that has an outflow to a stream, both this requirement and Minimum Requirement #8 apply. Applicant’s response: The City has read this section to mean” If stormwater is discharged to a wetland the stormwater is not flow control exempt. However, that is not what the rule says. There are two ways to read this section of the manual‐ one is by structure of the manual, the other by the plain text of the section. The City’s read of this section ignores both the structure of the manual AND the plain text of the section. CODE STRUCTURE The subject sentence above is not listed as a condition of exemption, but instead applies to non‐exempt projects. Section 2.5.7 states the following: Projects must provide flow control to reduce the impacts of stormwater runoff from impervious surfaces and land cover conversions. The requirement below applies to projects that discharge stormwater directly, or indirectly through a conveyance system, into a fresh water ‐ except for projects that discharge to a 2‐30 Volume I – Minimum Technical Requirements February 2005 water in Appendix I‐E ‐ Flow Control‐Exempt Receiving Waters in accordance with the following restrictions:. The “following conditions” are found in five bullet points (and two sub bullet points) as illustrated in this declaration document above. Only those points can be used to find for or against exemption. As shown above the subject project complies with those five bullet points. Everything else in Section 2.5.7 applies to non‐exempt projects. Once a project is found to be exempt, elements of the code from which the project is exempt cannot be used to apply conditions. Therefore, based on the construction of the code, the subject rule is not applicable to the subject project. Plain Language of the Code Section: Second, if one decides that the code construction does not exempt this project from the wetland section, then one must analyze the sentence structure to determine its meaning. The section in question states that: “If the discharge is to a stream that leads to a wetland, or to a wetland that has an outflow to a stream, both this requirement and Minimum Requirement #8 apply.” “If the discharge is to a stream that leads to a wetland” – The subject property discharges to a solid piped system, and not to a stream. So we can dispense with the first part of the sentence. “OR to a wetland that has an outflow to a stream” The subject property does not discharge to a wetland that discharges to a stream. The wetland in question is part of the tidal zone of the Snohomish and is below the ordinary high water. This wetland does not discharge into a stream. It is part of the Snohomish River. Therefore the wetland section in question does not apply. Volume 1 2.5.8 Minimum Requirement #8: Wetlands Protection The City has stated that the exemptions found in 2.5.7 do not apply because section 2.5.8 requires flow control. However as noted above, the exemption section of 2.5.7 exempts the project from flow control . Further the City gets direction to enforce section 2.5.8 from a non‐applicable section of 2.5.7 as described above in this document. Therefore, the detention requirements of 2.5.8 do not apply.