HomeMy WebLinkAboutGeo-Restoration Plan Review for BLD2004-00228 - BLD Engineering / Geo-tech Reports - 9/16/2004 Q�_STATFO
'MASON COUNTY
MO
o s o = PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER
N Shelton,Washington 98584
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~Z000 N Y boy DATE: September 16`h, 2004
M864
INTER-DEPARTMENTAL COMMUNICATIONS
TO: Diane Marcus Jones, DCD—Planner
Kristen French, DCD - Planner
FROM: Alan A. Tahja, P/W - Co. Hydr. Engr. WO#PLG-04
SUBJ: Geo-Restoration Plan Review NAME: Lessard SFR (& Mason Lake Drive East
BLD2004-00228
The geotechnical assessment, and vegetation restoration plan prepared for the Keith Lessard
residential property development located at 2931 Mason Lake Drive East, has been received and
reviewed by Public Works.
The restoration plan provides a course of action wherein the environmental impacts associated
with the tree and vegetation removal from a potential landslide hazard are buffer can be
mitigated. The restoration plan appears acceptable and raises no concerns regarding the
vegetation replacement.
Public Works recommends acceptance of the geo-assessment and the vegetation restoration plan.
Inspection of the TideMark files found no activity identified beyond restoration of the vegetative
buffer, so no further action is anticipated by Public Works.
Please feel free to contact me at County extension 461 if you have any questions regarding these
comments. Or if you feel additional concerns need further attention.
Sincerely,
Z—
A an A. Tahj a
File: H: \WP\GEO\Restoration Plans\Lessard.doc
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WORK ORDER - PUBLIC WORKS DEPT.
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Projed Stan date: `�—1 Estimated Fifth Date:
Approwdmate hour: ESTIMATED TOTAL$'S:
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LESSARD PROPERTY LAKE SHORE
SETBACK MITIGATION/REVEGETATION PLAN
Prepared for:
Keith Lessard
2803 NE 187`h Ave
Vancouver,WA 98682
SOUND
NATIVE
PLANTS
PO BOX 7505
OLYMPIA, WA 98507
(360) 352-4122
Prepared by:
Ben Alexander
June 14,2004
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LESSARD PROPERTY LAKE SHORE
MITIGATION/REVEGETATION PLAN
I. INTRODUCTION
This plan describes measures to mitigate construction impacts and restore native plants to the
disturbed areas of a lake shore buffer on property owned by Keith Lessard(parcel 222335200080)
located at 2931 East Mason Lake Drive East, Mason County, Washington. The property is the site
of a proposed single-family residence.
The required buffer-plus-setback has been determined according to the Mason County Resource
Ordinance (17.01.011 d.2.a.1)to follow a common line from the shore-side roofline of the
adjacent home on the east to the shore-side roofline of the adjacent home on the west. The
disturbed areas within the buffer will be revegetated with native plants.
II. EXISTING CONDITIONS
Vegetation. There is little existing vegetation in most of the 2,500 square foot area of the buffer,
except for one large Pacific madrone (Arbutus menziesii). Most of the shrubs and groundcovers have
been cleared down to bare ground throughout the buffer. A little vegetation remains along the west
property line, consisting of an overstory of Douglas fir(Pseudotsuga menziesii)with an understory of
evergreen huckleberry(Vaccinium ovatum), salal (Gaultheria shallon) and low Oregon grape (Mahonia
nervosa). The property to the east is unvegetated.
A small wetland at the foot of the buffer contains slough sedge (Carer obnupta), spirea(Spiraea
douglasii), lady fern(Athyrium felix,f emina)and creeping buttercup(Ranunculus repens). Refer to the
Lessard Property Wetland Delineation Report for more details.
Soil. The soil in the buffer appears to consist mainly of gravelly sandy loam. No clay layers, seeps,
or other indications of hardpan are visible in the slope.
Existing Impacts. A pre-existing brick outdoor fireplace sits in the southeast corner of the buffer,
with a level area in front of it. A 15' by 15' platform has been graded into the slope in the western
buffer. During the site preparation, vegetation was removed most of the buffer, except for a large
Pacific madrone. The disturbed area consists of 2,100 square feet of bare ground. Observation of
other undisturbed Mason Lake areas nearby indicates that the pre-impact vegetation most likely
consisted primarily of salal, evergreen huckleberry, snowberry and sword fern.
The existing soils appear to be undamaged native soils, there is no active erosion on the site, and
there is no evidence that any hydrology has been altered. The primary impact is the loss of native
shrubs and groundcovers.
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III. MITIGATION/REVEGETATION PLAN
A. Remove Sitting Area
The level platform that was graded into the slope in the western buffer area will be restored to the
original grade. The area was created by excavating soil from the upper portion and placing it below
to build up the platform. The soil placed below will be pulled back and replaced at the upper edge
to match the slope to the adjacent contours.
B. Install Native Plants
The disturbed area will be replanted with native plants. The species were chosen according to the
following criteria:
1. Native to western Washington and common in nearby undisturbed areas
2. Adapted to the existing, disturbed site conditions
3. Good root systems for slope stabilization
4. High potential for survival with minimal maintenance
5. Ability to spread rapidly
The plant quantities were calculated to achieve an average spacing of 6 feet on center for shrubs and
1 foot on center for groundcovers. This density, typical of restoration plantings, was specified in
order to provide fairly quick recolonization of native plant communities and to suppress invasive
nonnative species. Based on the preceding criteria, the following species were selected.
Common name Scientific name Size Qty Comments
Western snowberry Symphoricarpos albus 1 gal 19 Plant in steeper areas and restored sitting area
Thimbleberry Rubus parviflorus 1 gal 15
Red-flowering currant Ribes sangwneurn 1 gal 3
Pacific wax myrtle Myrica californica 1 gal 2 Plant behind fireplace for screening
Lady fern Ad 'um felix-femina 1 gal 7 Plant
Evergreen hucldeberry Vaccinium ovatum 1 gal 5 Plant behind fireplace for screening
Tall Oregon grape Mahonia a uifolium 1 gal 3
Coastal strawberry Fra aria chiloensis 4" 575
Kinnilrinnilr Arctosta h los uva-ursi 4" 1 300
The bare ground between the plantings will be covered with a 3"thick layer of mulch in order to
reduce weed growth, improve soil moisture retention, and reduce surface erosion. The mulch may
be arborist wood chips,medium ground bark, or"hog fuel".
The planting will occur between October 15 and March 1. The plantings will be watered and
weeded as necessary until they become established. Watering will be limited to weekly waterings
during periods of extended summer drought(2 weeks or more without measurable rainfall).
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IV. MONITORING
Monitoring will consist of checking the plants for survival and health. The plants will be checked
once per year in summer, for three years following installation. The presence of other native and
nonnative plants and other disturbances in the planted areas will also be noted. If fewer than 80%of
the plants survive after each monitoring, the dead plants will be replaced with plants of the same
size and species, unless substitutions are approved by Mason County. However, volunteer native
plants may be counted toward the total living plants.
A brief report summarizing the monitoring results will be submitted to the Mason County Planning
Department, with accompanying photographs. The report will describe any additional measures
needed to ensure success, and may make further recommendations to improve the overall project.
V. COST ESTIMATE
The estimated cost of installing this project is:
Plants and supplies $2,785.00
Labor 1-600.00
Sub-total 4,382.00
Sales Tax 363.71
Total $4,745.71
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View of buffer looking west. Level sitting area to be restored to original grade is
visible in center of photo. House on adjacent property is visible in background.
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Pre-existing brick fireplace.
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View of buffer looking northeast. House on adjacent property is visible in upper
right corner.
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