HomeMy WebLinkAboutM_Comment Response Letter_220715
Maple Highlands Preliminary Plat / LUA22-000122, ECF, PP Page 1
July 15, 2022
City of Renton
Community & Economic Development
Attn: Andrew Van Gordon
1055 S Grady Way, Sixth Floor
Renton, WA 98057
Subject: Comment Response Letter
Maple Highlands Preliminary Plat / LUA22-000122, ECF, PP
Dear Mr. Van Gordon,
Thank you for your comments provided in the “On Hold” Notice provided May 6, 2022. We have
addressed your outstanding comments and believe you will find our resubmittal package suitable for
full CED review and progression of the preliminary plat and civil construction permit processes.
Please do not hesitate to reach out directly if you have further comments or concerns.
Per your request, we have provided the following information to allow continued review of the
application:
Proof of authorization from the property owner that Timothy Prusa is authorized to act as their
representative. This has been provided to the City by Conner Homes separate from this
submittal.
Minimum lot width for Lot 4 has been increased to 80 feet.
A tree protection tract meeting the requirements of RMC 4-4-130H.2 has been proposed on
Lot 4.
Trees 110 and 111 are no longer proposed to be retained.
Significant trees have been retained in the order of priority presented in RMC 4-4-130H.1.b.
Addressing the Development Engineering portion of the comments:
Water
A water availability certificate has been provided with the resubmittal package
o See M_Water Availability Certificate_220203
Mr. Andrew Van Gordon
July 15, 2022
Maple Highlands Preliminary Plat / LUA22-000122, ECF, PP Page 2
Sewer
A sewer extension has been added to the north property line along 154th Ave SE.
o Per discussions with city staff, a sewer extension to the south property line along 154th
Ave SE is no longer required due to grading issues chasing the sewer extension
downhill to county line.
Surface Water
Core Requirement #2: Due to drainage concerns of the property owner of 13929 154th Ave
SE, a Level 2 downstream analysis taking the drainage complaint into account and addressing
a Type 3 – Severe Flooding Problem per the 2017 Renton Surface Water Design Manual
(RSWM).
o Per the analysis provided in the updated preliminary technical information report, the
downstream channel has sufficient capacity to convey the mitigated flow rates from the
proposed development.
Core Requirement #3: Updated TIR modeling accounting for the additional impervious surface
area in the existing City Right-of-Way on 154th and 152nd have been provided.
o Detention pond sizing and volume have been updated and reflect modeling based on
Flood Problem Flow Control Standard, matching forested site conditions for the 2-year
through 100-year return frequencies
o The pond access road cross slope has been removed
o Pond interior side slopes have been reduced to 3:1 or less
Core Requirement #4: Conveyance calculations for the downstream conveyance system have
been added.
Conveyance has been updated to meet minimum catch basin spacing standards and
minimum pipe diameter sizing per the RSWM.
Water quality treatment for the roadway widening for 152nd Ave SE and 154th Ave SE is
provided by the water quality portion of the stormwater pond.
Basic dispersion is not feasible for onsite stormwater management as property owners are
unlikely to maintain the designated vegetated flowpaths once moving in. However, the
reduced impervious surface credit; native growth retention credit; and tree retention credit are
proposed in flow control modeling as conservative estimates of the development footprint and
city required tree retention allow for their use.
Per discussions with City staff, geotechnical report section 5.6.3 (Infiltration) is sufficient to
determine BMP feasibility and support the conclusion that infiltration is no feasible.
Per discussions with City staff, a Construction Stormwater Permit from the Department of
Ecology will be obtained prior to civil permit issuance.
Per discussions with City staff, a Stormwater Pollution Prevention Plan is provided as part of
the Technical Information Report.
Mr. Andrew Van Gordon
July 15, 2022
Maple Highlands Preliminary Plat / LUA22-000122, ECF, PP Page 3
Per discussions with City staff, this resubmittal will be reviewed against the 2017 iteration of
the RSWM. Civil construction permit documents may be reviewed against the 2022 iteration
depending on the date of first submittal.
Transportation
Curb ramp placement has been updated per guidance from City staff.
Per discussion with City staff, an advisory note will be added to the land use approval that
street lighting plans will be provided with the Civil Permit Application.
Regards,
Tim Prusa
Civil Design Engineer
(206) 926-0586
tim.prusa@kpff.com