HomeMy WebLinkAboutSP200800058 Review Comments Critical Slope Waiver 2009-02-19*-&A
County of Albemarle
Department of Community Development
Memorandum
To: Joan McDowell, Principle Planner
From: Glenn Brooks, County Engineer
Date: 19 Feb 2009
Subject: Harris Garage (SP200800058) critical slope waiver request
The critical slope waiver request has been reviewed. The engineering analysis of the request follows:
Description of critical slope area and proposed disturbance:
The two areas of critical slope disturbance consisted of a large wooded slope leading down to the stream
on the rear, eastern property line, and a steep wooded slope behind the building on the northern property
line. The applicant has already disturbed these areas in violation of the ordinance and existing special use
permit plans. The applicant is proposing to stabilize the northern slope behind the building with seed and a
small wall at the toe, and to leave the eastern slope as -is.
Areas
Acres
Total site
3.23 acre parcel
Critical slopes
0.37
12% of site
Critical slopes disturbed
0.3
81 % of critical slopes
Exemptions to critical slopes waivers for driveways, roads and utilities without reasonable
alternative locations:
This disturbance is not exempt.
Compliance with Zoning Ordinance 18 -4.2:
"movement of soil and rock"
The slopes have not been properly constructed. They are slightly steeper than 2:1 in places, which is
not inherently stable for most soils in Albemarle. The slope in back of the building is an exposed cut.
The slope down to the creek is slightly convex, with exposed boulders and debris, and a light covering
of new grass. It does not appear to have been properly compacted. The northeast corner is loose fill
with rubble and exposed rebar placed amid the trunks of small trees which will likely die.
"excessive stormwater runoff'
Stormwater runoff has been increased in these areas with steeper slopes than original, less vegetation,
and more impervious area behind the building.
"siltation"
Most siltation has already taken place. Long term stability may be an issue.
"loss of aesthetic resource"
This area is visible from the surrounding properties.
"septic effluent"
This does not appear to be an issue, but the applicant has provided no information on this topic.
Based on the review above, if the Planning Commission approves the request, the following conditions are
Albemarle County Community Development
Engineering Review comments
Page 2 of 2
recommended;
1. The eastern facing slope above the creak must be reshaped to a uniform grade not steeper than
2H:1 V, covered with erosion control matting, and permanently seeded.
2. The retaining wall proposed in the rear of the building must be at least 3' high, and topsoil,
matting, and permanent seed or mulch and shrubs must be applied to the cut slope for adequate
stabilization.
3. To provide stormwater management and replenish the buffer, the entire buffer area within the
property should be planted in accordance with the Chesapeake Bay Riparian Buffers Modification
and Mitigation Guidance Manual. (The applicant is referred to the Restoration Establishment
Tables in Appendix D, calling for canopy trees at 6' centers, understory trees at 4' centers, and
shrubs at 18" centers.) These should be bonded as a guarantee of survival for at least 5 years.
file: El_csw_GEB_HarrisGarage.doc