LAND USE RESPONSE
Date: April 8, 2008
To: Suzanne Savin, BDS Land Use Services 503-823-5888
From: Stephen Himes, BES Development Services 503-823-7875
Subject: LU 08-106691 AD
Location: Site on west side of SW 18th Ave, south of Highway 26 Quarter Section: 3127
R No: R140407580
The following conditions of approval and informational comments are based on the land use review information provided to the Bureau of Environmental Services (BES). The applicant may contact me with any questions or concerns.
Proposal Summary: New multi-dwelling project on hillside lot - adjustments to reduce west/front setback, north/side setback, and to increase height
BES Summary Response: BES cannot recommend approval of the requested adjustments at this time, due to insufficient evidence that stormwater runoff from the development can be accommodated in a manner consistent with the Stormwater Management Manual. Considering the site constraints and the adjustments that are being requested, BES requests stormwater calculations and a revised site plan showing that applicable pollution reduction and flow control requirements of the SWMM can be met. In addition, BES requests a revised site plan that clearly depicts a building footprint that does not encroach in the public easement. Please see below for additional comments.
Sanitary Services
1. There are several public combination sewer mains in the vicinity of the subject site:
▪ There is an existing public 6” CSP combination sewer main in the ODOT right-of-way north of the site.
▪ There is an existing public combination sewer system in SW 18th Avenue that varies in size (30”-36”) and material (concrete and brick with stone invert).
2. There is a public sewer easement over the north-west corner of the subject site that the applicant has not shown on their site plan, and it appears that the proposed structure encroaches in this easement. This is not acceptable to BES. Note that all public easements are exclusive, and no other utilities, facilities, building construction, material storage, grade reduction, tree planting, or other easements are to be located within the boundaries of public sewer easements without prior written consent of the Director of BES. BES cannot recommend approval of the setback and building coverage adjustments until it is clear that the applicant has made consideration for this easement in planning the site layout.
3. It appears per City records that there is an existing sanitary service lateral available for use by this development to the combination sewer in 18th Avenue. The diameter of this current lateral is not clear; at the time of building permit, this lateral should be evaluated and BES may require the lateral to be upsized at the applicant’s/owner’s expense.
4. Please note that new connections to the public sewer must follow BES's "Rules of Connection" and meet the standards of the City of Portland's Sewer and Drainage Facilities Design Manual. The Design Manual is on the internet at www.portlandonline.com/bes/, and contains the “Rules of Connection” in Appendix H.
Stormwater Management & Water Resources
The stormwater runoff generated from the proposed development must meet the requirements of the City of Portland’s Stormwater Management Manual (SWMM) current at the time of building plan review. For all projects, the Stormwater Destination/Disposal Hierarchy must be addressed (pages 1-18 and 1-19 of the SWMM). Free CD-ROM discs of the 2004 SWMM are available at the City of Portland Development Services Center, 1900 SW 4th Avenue or on the internet at www.portlandonline.com/bes/. The applicant may also contact BES with any questions or for additional information.
1. There are no public storm-only sewers in the vicinity of the subject site.
2. Currently the street and surrounding area is served by a public combination sewer. The combined nature of flow in this system – i.e. both stormwater and sanitary discharge in the same pipes – is a primary contributing factor to combined sewer overflows (CSOs). Therefore, the SWMM requires that stormwater be managed on-site through surface infiltration facilities to the maximum extent practicable. Where approved by BDS Site Development, roof runoff may be managed in drywells or soakage trenches, and surface (i.e. parking lot, driveway and other ground-level impervious area) runoff must be managed in surface infiltration facilities. Pollution reduction is required for all non-rooftop runoff, and all runoff that is not infiltrated on site. Flow control requirements must be met for most runoff that is disposed off-site. A disposal location for stormwater must be identified for any size development, and any proposed new connections or additional stormwater disposal to the combination system will be restricted through requirements of the SWMM. PLEASE NOTE: Constraints based on small lot size is not considered a basis for waiving any requirements of the 2004 SWMM.
3. BDS Site Development has indicated that on-site infiltration will not be feasible at this location; therefore, categories 1 and 2 of the Destination/Disposal Hierarchy may not be utilized. Treatment and detention will still be required in the SWMM prior to off-site disposal to the combination sewer system. The current site plan shows flow-through planters along the edges of the second floor garden terrace and along the north-eastern edge of the building. This is conceptually acceptable to BES; however, due to the natural constraints of the site, and considering the adjustments that are being requested, BES cannot recommend approval of this review until the applicant has submitted a stormwater report that clearly shows there is available area for flow-through planters that are sized according to the SWMM and that meet facility setback requirements to lot lines.
4. Any proposed public street improvements (required by the Office of Transportation) may require public drainage improvements per the standards of the SWMM and Sewer Design Manual, as approved by BES. Details regarding street improvement requirements shall be determined at the time of the Office of Transportation’s Pre-design Meeting. Please see the response from the Office of Transportation for more information.
Additional Information
1. BES sewage system connection fees are assessed at the time of building plans review and change every fiscal year beginning July 1st. For additional information on these fees, please call Development Assistance at 503-823-7761.
Future Building Permit Requirements
1. Building plans for this project must include a detailed site utility plan which shows proposed and existing sanitary connections, as well as stormwater management that meets the requirements of the version of the SWMM that is in effect at the time permits are submitted.