RevisedNativeVegetationPlanComments_20160302.pdf
TECHNICAL MEMORANDUM
TO: Kernen Lien
City of Edmonds Development Services Department
FROM: Steven Quarterman and Carlo Evangelisti, P.E.
DATE: March 1, 2016
R: PR
EEER EVIEW
PTTNGPE
ROPOSED REE OPPING IN ATIVE ROWTH ROTECTION ASEMENT
ME
EADOWVIEW STATES
E,W
DMONDS ASHINGTON
I
NTRODUCTION
Meadowview Estates is a 4-lot subdivision in the North Edmonds Earth Subsidence Landslide
Hazard Area (ESLHA). In accordance with ECDC 23.90.040.C, the development required retention of 30
percent native vegetation. The 30 percent native vegetation area was also established as a native growth
protection easement through the subdivision process. The language of the native growth protection
easement is:
easement unless documentation is submitted that can demonstrate that the removal will enhance the
easement area and will not impact slope stability. Enhancement may include nonmechanical removal of
noxious or intrusive species or dead or diseased plants and replanting of appropriate native species. The
native growth protect easement may be maintained consistent with the native vegetation plan located in
The property owner has proposed topping of trees within the native growth protection easement
and submitted a habitat assessment of the proposal. Landau Associates assumes that the City has
determined that the proposed action constitutes a removal of trees and is subject to the easement criteria
as provided above. ECDC 23.90.40.320 defines enhancementan action taken to improve
the condition and function of a critical area.
Landau Associates biologist and geotechnical engineer conducted a peer review of the December
3, 2015 Meadowview Estates Property Wildlife Assessment (Wildlife Assessment) prepared by Avia
Environmental Consulting and June 12, 2013 and October 22, 2015 geotechnical evaluations prepared by
Geotech Consultants, Inc.
The purpose of this peer review is to provide a professional opinion as to whether the proposed
tree topping a Landau Associates staff
130 2nd Avenue South Edmonds, WA 98020 (425) 778-0907 fax (425) 778-6409 www.landauinc.com
conducted a reconnaissance of the site on February 23, 2016 to supplement assessment of site conditions
provided in the above listed consultant reports.
WA
ILDLIFE SSESSMENT
The Wildlife Assessment indicates:
intended to increase habitat value over existing conditions.
Final mitigation was not been designed \[sic\] at the time this report was completed, but the
implementation of the recommendations in Section 8 of this report will result in more diverse
vegetation composition and structure, which will increase foraging, nesting, resting, and travelling
opportunities for wildlife. Over time, with continued maintenance, the area is expected to return to
pre-
The peer review comments regarding the Wildlife Assessment include:
1.
Associates understanding that selective topping of trees is proposed and no clearing activities
will occur.
2.Section 8 as referenced above does not include a planting plan demonstrating what additional
native species will be provided to increase native species diversity in the easement area.
3.Section 8 references that site performance will be monitored and native vegetation replanted
if topped trees fail to branch as intended. The Wildlife Assessment indicates that topping
may promote growth of groundcover as a result of temporary increase in sunlight that will
occur following the topping of the trees. It should also be anticipated that there is potential
for the expansion of existing or establishment of new noxious or intrusive species in the
easement area. It is recommended that site performance be expanded to include monitoring
of noxious or intrusive species, and reference appropriate remedial actions that enhance the
easement area (e.g., removal and replacement with native species).
4.Pursuant to the definition of enhancement, the expectation of the impacted areas to return to
pre-disturbance condition does not demonstrate improvement to the condition and function of
the area to be impacted.
Based on the comments provided above, it is our opinion that the Wildlife Assessment does not currently
demonstrate that the proposed tree topping will result in an enhancement of the easement area.
GA
EOTECHNICAL SSESSMENT
During our reconnaissance, we observed the steep slopes on the western edge of the property to
be in a relatively stable condition. It should be noted that the steep slopes in the ESLHA have
experienced slope instability in the past as evidenced by observed topography indicative of head scarps
and landslide debris masses-
within the vicinity of the Meadowview Estates subdivision.
LA
ANDAU SSOCIATES
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Based on our review of the December 3, 2015 Meadowview Estates Property Wildlife
Assessment (Wildlife Assessment) prepared by Avia Environmental Consulting and June 12, 2013 and
October 22, 2015 geotechnical evaluations prepared by Geotech Consultants, Inc., we concur with
Geotech Consultants that topping of the trees will not impact slope stability.
If tree topping is approved by the City, we recommend that the recommendations provided by
Geotech Consultants related to removal of trimmed branches and foliage be strictly adhered to. We
recommend that an arborist occasionally check the condition of the trees to ensure that the topped trees
are alive and growing. Should it be found that some of the trees have died, the geotechnical
engineer should observe the condition of the slope and provide an opinion and recommendations
regarding the risk of slope instability due to death and/or removal of the trees.
C
ONCLUSION
Based on review of documents provided to Landau Associates by the City, it is our opinion that
the applicant has not adequately demonstrated that the proposed tree topping within the native growth
protection easement associated with the Meadowview Estates subdivision will enhance the easement area.
However, Landau Associates concurs that the proposed tree topping, if performed in accordance with
will not impact slope stability.
* * * * *
This technical memorandum has been prepared for use by the City of Edmonds in evaluating the
adequacy of the Wildlife Assessment and geotechnical reports to demonstrate enhancement of the
proposed action on the easement area and effect on slope stability. The purpose of the review was to
assess the adequacy of the submitted documents for compliance with City requirements as promulgated in
the native growth protection easement and conformance with conventionally accepted engineering,
critical areas, and mitigation practices.
We appreciate this opportunity to be of service to the City. Please contact us if you have any
questions or if we may be of further service.
SJQ/CE/SZW/rgm
LA
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