HomeMy WebLinkAboutM_Comment Response Letter_221031
Maple Highlands Preliminary Plat / LUA22-000122, ECF, PP Page 1
October 31, 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 August 5, 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:
ADDITIONAL INFORMATION REQUESTED
1. Comment: Significant trees shall be retained in the order of priority presented in RMC 4-
4-130H.1.b. The first two (2) items for Priority One are (i) landmark trees, and (ii)
significant trees that form a continuous canopy. Trees 97 through 101 meets both items
and are of the highest priority to preserve. The first two (2) items for Priority Two are (i)
healthy tree groupings whose associated undergrowth can be preserved, and (ii) Other
significant native evergreen or deciduous trees. Trees 1 through 30 meet these priorities.
Tree 105 meets the third item of Priority Two, (iii) other significant non-native trees.
Preservation. Preservation of Trees 1 through 30, 97 through 101, and 105 is a priority
for Planning as they meet multiple priority items and can be retained through
development. Trees 1 through 30 can be retained in a tract and still maintain R-4 zoning
minimum lot requirements. Planning will not support removal of them. Retention of an
arborist to monitor construction with lower impact construction around Trees 97 through
101 and 105 will be a recommended condition of approval.
Response: Since last submittal, the city has graciously discussed tree retention
strategies at length with the developer. An additional memo from the arborist
summarizing the project approach to tree retention has been provided. Additional
email correspondence between Conner Homes and City of Renton CED is also
included as a separate attachment.
Mr. Andrew Van Gordon
October 28, 2022
Page 2
Maple Highlands Preliminary Plat / LUA22-000122, ECF, PP Page 2
DEVELOPMENT ENGINEERING COMMENT RESPONSES
CIVIL PLANS
2. Comment: Storm Pond Access Road Grading: the slope for the road exceeds the
maximum 15%. Ensure that turning radius is minimum 40 feet. Revise road.
Response: Storm pond access road has been revised to be under the maximum
15% grade with a minimum turning radius of 40 feet. See sheet C4.0 for revised
access road.
3. Comment: Storm Pond Walls: Based on the elevations, it appears that the storm pond
walls protrude above the ground surface, roughly 3 feet. Show the exposed height
elevations for clarity.
Response: Additional detail has been added to sheet C4.0 noting the exposed wall
heights of storm pond walls.
4. Comment: Storm Pond Berm: Berm top minimum width must be 6 feet.
Response: The storm pond berm is a minimum of 6 feet wide. See C4.0 for
dimensioned pond berm.
5. Comment: Suggestion: may want to consider a detention vault due to grading, setbacks,
and retaining wall height restrictions.
Response: Noted. The revised pond now meets or exceeds City of Renton
combination detention wet vault standards.
DEVELOPMENT ENGINEERING COMMENT RESPONSES
TIR
6. Comment: BMP: Basic Dispersion is feasible, per 25-foot vegetated flow path. This BMP
shall be considered.
Response: Basic dispersion has been considered and applied on each of the 12
lots. See TIR Core Requirement #9 and Appendix E for additional information.
7. Comment: New street runoff on 154th Avenue SE must be captured and treated via the
pond. Revise this.
Response: New street runoff on 154th Avenue SE is now being captured and
treated in the pond to the maximum extent feasible. Areas bypassing the pond are
accounted for in the stormwater model. See sheet C4.0 for revised storm layout.
Mr. Andrew Van Gordon
October 28, 2022
Page 3
Maple Highlands Preliminary Plat / LUA22-000122, ECF, PP Page 3
8. Comment: Flow Control Table: provide detention pond Information in a table, in the TIR
(Depth of Pond, Detention Volume (Live), Riser Height, Riser Diameter, Orifice 1 &2
diameter & elevation).
Response: Additional pond information has been provided in the flow control table.
See Core Requirement #3, Table 3-4 for additional pond information.
DEVELOPMENT ENGINEERING COMMENT RESPONSES
MITIGATION
9. See attached flood photos from neighboring properties. Mitigation measure, can be
addressed at the civil permit review (after LUA): replace two (2) existing driveway
culverts with 12” Ductile Iron Pipe, and design new ditch to convey flows from 18”
outfall to 3rd driveway (see screenshot below):
Responses: As discussed in the “On Hold” Notice, any additional mitigation
measures will be addressed at the civil permit review following the preliminary plat
land use approval process.
As the pond is already providing a reduction in runoff generated during the 100-year
storm event, exceeding flow control measures required for a Type 3 – Severe
Flooding problem, additional flow control measures are not warranted. Neither the
provided photos or the findings of the previously requested Level 2 downstream
analysis found evidence of downstream erosion or washout in the current conditions
today.
While the attached photos are undated, review of the provided photos against historic
aerials and current conditions indicates the flooding shown occurred before
construction of the neighboring plat and associated stormwater pond to the east on
SE 5th Place. See attachments for a timeline of the neighboring development relative
to the undated flooding in the provided photos.
If there are any further comments or questions, please feel free to call me at (206) 622-5822.
Regards,
Tim Prusa
Civil Design Engineer
(206) 926-0586
tim.prusa@kpff.com
Looking north on 154th Ave SE,
undated flooding photo
Tree removed
during construction
of neighboring plat
to the east
Tree removed during
construction of neighboring
plat to the east
Looking north on 154th Ave SE,
undated flooding photo
Looking north on 154th Ave SE,
current conditions
Location of tree
removed during
construction of
neighboring plat
to the east
Tree removed
during construction
of neighboring plat
to the east
Tree removed
during construction
of neighboring plat
to the east
Tree removed
during construction
of neighboring plat
to the east
Tree removed
during construction
of neighboring plat
to the east