HomeMy WebLinkAboutSUB201100111 Review Comments Critical Slope Waiver 2012-03-26�OF �
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County of Albemarle
Department of Community Development
Memorandum
To: Ellie Ray, Planning Review
From: Phil Custer, Engineering Review
Date: 26 March 2012
Subject: SUB - 2011 - 00111; Belvedere Phase 2 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 critical slope disturbance proposed by this plat is consistent with the development plan first approved
by the Board of Supervisors with ZMA- 2004 - 00007. Though, the current plan shows a greater limits of
disturbance than first conceived with the rezoning plan, mostly because the rezoning plan was not
practically designed with regard to stormwater management and erosion and sediment control; increases to
critical slope disturbance occur around stormwater facilities 1 and 2. To achieve the density desired by the
rezoning plan, these increased impacts are necessary. The remainder of the disturbed critical slopes is
internal to the site for the construction of the street network and individual lot grading.
Analysis for all five parcels:
62A3 -01, 62 -02A1, 61 -160, 62 -03, and 62 -05
Areas
Acres
Total site
122.2 acres approximately
Critical slopes
22.9
18.7% of site
Critical slopes disturbed
0.49*
12.1% of critical slopes
Project Area as delineated by the Applicant, bounded by the zoning limits
Areas
Acres
Total site
31.47 acres approximately
Critical slopes
0.71*
2.2% of site
Critical slopes disturbed
0.49*
69% of critical slopes
*These figures have been provided by the applicant and I suspect they were generated by a CAD program.
However, in measuring the existing topography provided in this set, I have found a few areas of slopes
steeper than 25% that were not graphically shown on sheet 2. These additional areas of critical slope do
not affect the engineering review of this request.
Exemptions to critical slopes waivers for driveways, roads and utilities without reasonable
alternative locations:
It is possible to make the argument that the critical slope disturbance to construct the stormwater facilities
may be considered exempt. However, because of the modifications made to the concept plan, I do not
think the exemption should be extended to these disturbances.
Compliance with Zoning Ordinance 18 -4.2:
"movement of soil and rock"
Proper slope construction, control of drainage, and vegetative stabilization will prevent any movement
Albemarle County Community Development
Engineering Review comments
Page 2 of 2
of soil.
"excessive stormwater runoff'
The project will be required to detain post development runoff to pre - development rates and prove
adequacy of the downstream channel.
"siltation"
Inspection and bonding by the County will ensure siltation control during construction. Proper
stabilization and maintenance will ensure long term stability.
"loss of aesthetic resource"
The decision that the loss of aesthetic resources was outweighed by the proposed development was
made with approval of the rezoning plan.
"septic effluent"
This neighborhood will be serviced by public sewer.
Based on the review above, there are no engineering concerns which prohibit the disturbance of the critical
slopes as shown.
file: El csw PBC Belvedere Phase 2.doc