HomeMy WebLinkAboutRS_SVC Site Visit Memo_180405_v1
Soundview Consultants LLC April 4, 2018
1155.0024 – Harbour Homes Page 1
2907 Harborview Drive, Suite D
Gig Harbor, WA 98335
Technical Memorandum
To: Alex Morganroth, Associate Planner File Number: 1155.0024
City of Renton, CED, Planning Division
From: Don Babineau, Environmental Planner Date: April 4, 2018
Re: 14120 160th Ave. SE- Technical Memorandum - Ref. No.: 32847.B - follow-up site visit.
Dear Alex Morganroth,
Thank you for taking the time to meet with our team and OTAK onsite on March 14, 2018. This
memorandum is in response to the comments made during the meeting with OTAK regarding the
critical areas review for the proposed Cedars at the Highlands preliminary plat located at 14120 160th
Avenue Southeast in Renton, Washington, 98059 (King County Parcel number 145750-0110).
Non-Wetland Areas and Onsite Southern Drainage
Otak and Soundview Consultants LLC (SVC) discussed the ponded areas in the northwest portion of
the site which Sewall originally assessed as uplands prior to the recent fill brought onto the site. OTAK
agreed that the SVC memo adequately assessed and documented the area as anthropogenically altered
as a result of the compacted fill and was not a natural wetland area. As such, it was agreed the area
would not be considered a regulated critical area. The culverted drainage through the ponded area
draining to the southeast corner of the site was also determined to be a nonregulated manmade feature.
Wetland A and Associated Drainage
Otak and SVC discussed Wetland A and the associated drainage through the wetland. While the
drainage associated with Wetland A does not meet the definition of a stream per City of Renton code
as it does not flow to a perennial waterbody via an above ground channel system, because the channel
exhibited natural stream like characteristics, it was agreed that the drainage would be treated as a Type
Ns stream.
While Otak staff agreed with the delineation of Wetland A, they maintained their assessment of the
hydrogeomorphic (HGM) classification of the wetland as a depressional wetland. SVC does not
concur with this classification. From the onsite inspection, it was clear there is no significant
depressional function of the wetland to meet the threshold of being classified as a depressional
wetland. While there are obstructions (tree branches and logs) slightly impeding the surface flow of
the drainage within the wetland, there are not adequate depressions within the streambed to classify
the wetland as depressional. To confirm the lack of depressions within Wetland A, following the site,
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visit SVC conducted a highly precise LIDAR analysis of the topography of the wetland area (see
Attachment A). From the analysis it is clear to see the geomorphology of Wetland A resembles a
chute with an even gradient along the channel and no depressions or hummocks which would create
depressional areas. For a wetland to be depressional, it must impound water. Wetland A does not
have the capability to significantly impound water.
SVC correctly used the accepted HGM classification system as outlined by Brinson (1993) and in
accordance with Section 5.1 and the classification key of the rating form located in Appendix A of the
Washington State Wetland Rating System for Western Washington (Hruby, 2014). Otak staff cited a portion
of Section 5.1 during the sit visit as justification for classifying Wetland A as depressional and the
citation was one sentence taken out of context. He said that according to the manual, slope wetlands
do not receive water through surface flow. The following is the full, accurate portion of the manual
to which he referred:
Slope wetlands with surface flows can be distinguished from Riverine wetlands by the lack of a
defined stream bed with banks. Slope wetlands may develop small rivulets along the surface, but
they serve only to convey water away from the wetland. There is no surface flow coming into the
wetland through channels.
This portion of the manual is in regard to distinguishing slope versus riverine wetlands, and it was
agreed Wetland A is clearly not a riverine wetland. This portion of the manual has nothing to do with
determining if a wetland is depressional.
To determine a wetland’s HGM classification, the rapid assessment procedure is to follow the key
located in the front of the 2014 rating form which consists of a set of progressive yes/no
questions. The first three questions on the key determine if the wetland is either a tidal fringe, flats,
or lake fringe wetland and are obviously not applicable. The fourth question deals with slope wetlands
and has three criteria required to meet the classification:
• The wetland is on a slope,
• The water flows through the wetland in one direction and usually come from seeps. It may
flow subsurface, as sheet flow or in a swale without distinct banks,
• The water leaves the wetland without being impounded.
Wetland A has a clear, continuous slope with seasonal main channel flowing through it and a saturated
slope edge which feeds into the main channel. Hydrology flows through the wetland in one direction.
The wetland receives its hydrology from groundwater and direct precipitation and leaves the wetland
without significant impoundment. The second criteria may appear to add some uncertainty but having
a stream channel at the lowest point cross-sectionally within a slope wetland is common. Technically,
Wetland A is actually two separate wetlands flowing on either side of the stream channel to that
channel; however, per the 2014 manual guidance, slope wetlands are to be treated as one wetland
when the stream bisecting them is as narrow as Stream Z. From the attached LIDAR exhibit, it is
clear to see that most of the wetland area is uphill from the channel running through the wetland. This
is an important distinction because it shows the wetland does not receive the majority of its hydrology
from the stream. Instead, it contributes to the stream’s hydrology through lateral flow to the central
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stream channel. At times of heavy flow, the stream will encroach on a small portion of the wetland
area, but this increased flow is not the main source of wetland hydrology. When the stream stops
flowing, Wetland A persists in its hydrated state because groundwater is the wetland’s main source of
hydrology.
A depressional classification would infer that the wetland has areas of significant impoundment that
would allow for stagnation and fallout of particulates. The wetland on the subject property was
observed to have micro-depressions that are receiving flow from the main channel, however these
micro-depressions were observed to be continuously flowing, highly oxygenated, and not providing
the potential for anaerobic conditions. Soil data supports these observations with a lack of obvious
hydric soil conditions that would be expected in a depressional wetland.
Conclusion
Because the Wetland A is properly classified as a slope wetland, it is accurately rated per SVC’s
previous assessment as a Category IV wetland which requires a standard 40-foot buffer per Renton
Municipal Code (RMC) Title IV, Chapter 3 (4-3-500). Per SVC’s original assessment and the site
meeting, this is the only regulated wetland onsite. SVC and Otak agreed the drainage flowing through
Wetland A is the only regulated stream feature and should be treated as a Type Ns stream requiring a
50 -foot buffer per RMC Title IV, Chapter 3 (4-3-500).
Please contact me with any questions or concerns you may have regarding this matter.
Sincerely,
April 4, 2018
Don Babineau Date
Environmental Planner/Project Manager
Soundview Consultants LLC
2907 Harborview Drive, Suite D
Gig Harbor, WA 98335
don@soundviewconsultants.com
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References
Brinson, M. M., 1993. “A Hydrogeomorphic Classification for Wetlands,” Technical Report WRP
DE-4, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.
Cowardin, L.M., V. Carter, F. Golet, and E.T. LaRoe. 1979. Classification of Wetlands and Deepwater
Habitats of the United States. U.S. Fish & Wildlife Service. Washington D.C.
Environmental Laboratory. 1987. Corps of Engineers Wetlands Delineation Manual. Technical Report Y-
87-1, US Army Engineer Waterways Experiment Station, Vicksburg, Mississippi.
Federal Geographic Data Committee. 2013. Classification of Wetlands and Deepwater Habitats of
the United States. FGDC-STD-004-2013. Second Edition. Wetlands Subcommittee, Federal
Geographic Data Committee and U.S. Fish and Wildlife Service, Washington, DC.
Hruby, T. 2014. Washington State Wetland Rating System for Western Washington – Revised.
Washington State Department of Ecology Publication # 14-06-029.
Lichvar, R.W., D.L. Banks, W.N. Kirchner, and N.C. Melvin. 2016. The National Wetland Plant
List: 2016 wetland ratings. Phytoneuron 2016-30: 1-17. Published 28 April 2016. ISSN 2153
733X
Munsell Color. 2000. Munsell Soil Color Charts. New Windsor, New York.
Natural Resources Conservation Service (NRCS). 1995. Hydric Soils of Washington. U.S. Department
of Agriculture. Washington D.C.
NRCS. 2001. Hydric Soils List: King County, Washington. U.S. Department of Agriculture. Washington
D.C.
Null, William, Skinner, Gloria, and Leonard, William. 2000. Wetland Functions Characterization
Tool for Linear Projects. Washington State Department of Transportation.
OTAK, Inc. 2017. Review of Sewall Wetland Consulting, Inc. Critical Areas Report. Redmond,
WA.
Renton Municipal Code (RMC). 2017. Title IV, Chapter 3 – Environmental Regulations and
Overlay Districts. Passed December 11, 2017.
Snyder, Dale E., Gale, Philip S., and Pringle, Russell F. 1973. Soil Survey of King County Area,
Washington. Soil Conservation Service.
U.S. Army Corps of Engineers. 2010. Regional Supplement to the Corps of Engineers Wetland Delineation
Manual: Western Mountains, Valleys, and Coast Region (Version 2.0), ed. J. S. Wakeley, R. W. Lichvar,
and C. V. Noble. ERDC/EL TR-10-3. Vicksburg, MS: U.S. Army Engineer Research and
Development.
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Attachment A – Lidar Analysis Exhibit
CEDARS OF THE HIGHLAND - LIDAR EXHIBIT
DATE:
JOB:
BY:
SCALE: VARIES
FIGURE NO.
3/16/2018
DLS
1
CEDARS AT THE HIGHLANDS
14120 160TH AVE SE, RENTON, WA 98059
KING COUNTY PARCEL NUMBERS:45750-0106
1155.0024
! ! ! ! ! !Wetland Centerline
Wetland Boundary
Elevation in Feet
426.6 - 428.1
425.7 - 426.6
425 - 425.7
424.3 - 425
423.7 - 424.3
423.1 - 423.7
422.5 - 423.1
421.8 - 422.5
421.1 - 421.8
420.3 - 421.1
419.6 - 420.3
418.8 - 419.6
418.1 - 418.8
417.3 - 418.1
416.6 - 417.3
415.9 - 416.6
415.3 - 415.9
414.7 - 415.3
414 - 414.7
413.3 - 414
412.5 - 413.3
411.8 - 412.5
411.2 - 411.8
410.4 - 411.2
409.5 - 410.4
408.7 - 409.5
407.8 - 408.7
407.1 - 407.8
406.5 - 407.1
405.9 - 406.5
405.2 - 405.9
404 - 405.2
Top Elevation
418.5 Feet
Bottom Elevation
408 Feet
Length of Centerline
316 Feet
Wetland A
3.3% Slope ¢
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Attachment D – Qualifications
Don Babineau
Environmental Planner/Project Manager
Professional Experience: >10 years
Don Babineau is an Environmental Planner and Project Manager with a diverse background in urban
and commercial forestry, land planning, landscape architecture, stormwater monitoring and civil
engineering. Don has experience as a Forester with Washington State Department of Natural
Resources stream typing and delineating stream protection zones, as well as implementing Washington
State’s Habitat Conservation Plan to foster the creation of old-growth forest characteristics on state
trust lands. Don earned a Bachelor of Science degree in Forest Ecosystems Management and a
Bachelor of Landscape Architecture degree, both from the University Of Idaho.
Don has been formally trained by the Washington State Department of Ecology in the use of the
Washington State Wetland Rating System. In addition, he has received formal training in wetland
delineation from the Northwest Environmental Training Center and is an experienced certified
erosion and sediment control lead (CESCL). He is also a Pierce County qualified Professional
Forester.
Richard Peel
Wetland Scientist
Professional Experience: 5 years
Richard Peel is a Wetland Scientist with professional experience in wetland ecology, monitoring, and
delineation throughout Washington and Oregon. Richard is Washington State trained in conducting
wetland delineations, assessing wetland systems, mitigation planning and design, implementation of
monitoring programs, mitigation monitoring and reporting. He also has extensive experience in an
analytical laboratory using state-of-the-art equipment in bacteriological and chemical analysis of soil and
water samples.
Richard is a graduate of The Evergreen State College, with dual degrees in Ecology and Economics. He
has focused his academic career on ecology, disturbance ecology, chemistry, and the economic impacts of
current environmental management. Richard has extensive training and field experience in wetland related
disciplines, and has experience in wetlands both east and west of the Cascades. He has been trained by the
Washington State Department of Transportation (WSDOT) Wetland Ecology and Monitoring team in the
use of the wetland delineation, mitigation, monitoring, and restoration techniques. In addition, he was
directed by WSDOT’s Wetland Protection and Preservation Policy to ensure wetlands are preserved and
protected whenever possible. This direction ensures no net loss in the quantity or quality of wetlands in
the future and minimization of impacts to wetlands in the present.