HomeMy WebLinkAboutSDP201000022 Review Comments Critical Slope Waiver 2010-05-05�'IRGI1�1�
COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
To: Elizabeth Marotta, Senior Planner
From: Amy Pflaum, Current Development Engineering Review
Subject: SDP20100022, Arden Place, Critical Slope Waiver Request
Date received: 28 April 2010
Date of Comment: 5 May 2010
The request for a waiver to develop on areas of critical slope for grading incorporated with proposed
development on TMP 32 -56 was received on 28 April 2010. The existing critical slopes and proposed
grading are shown on the Preliminary Site Plan dated April 26, 2010.
The engineering analysis of the request follows:
Description of critical slope area and proposed disturbance:
The critical slope areas within TMP 32 -56 contain both natural and presumably manmade critical slope
areas. Please see the applicant's waiver request for details on these areas and the percentages of
disturbance. After a site visit, County staff surmises that the majority of critical slopes on the parcel are
the result of a previous fill operation in the area. Critical slopes disturbance is for the construction of an
apartment building and adjacent parking.
Below, each of the concerns of Zoning Ordinance section 18 -4.2 is addressed:
1. "rapid and/or large scale movement of soil and rock ": The areas of critical slope
disturbance are presumed to be fill area from previous development in the area. Large scale
movement of soil and rock is not anticipated to occur as a result of this construction.
2. "excessive stormwater run - off": Although it does not affect the critical slopes disturbance,
the proposed stormwater management facility appears to conflict with a future road
connection from the approved Willow Glen development to Towncenter Drive. Regardless,
excessive stormwater run -off in the area of critical slopes can be limited by site design that
minimizes or terraces runs of steep slopes (2:1). Proposed Building #6 has been designed as
a "split- level" with a 10 -foot step differential to accommodate the existing topography as
much as possible. Adjacent Building #5, although not directly located on the area of critical
slopes, is only proposed with a 2 -foot step differential, creating the need for a 16 -foot vertical
2:1 fill slope behind it. It is recommended that this building be designed with a greater step
differential, if possible, to shorten this 2:1 slope or that the 2:1 slope be terraced with areas of
flatter grade.
3. "siltation of natural and man -made bodies of water ": A natural stream runs along the
northern boundary of this parcel and needs to be adequately protected from construction
activities. Grading and fill activity in close proximity to proposed Woodland Preservation
areas appears to leave inadequate room for Erosion & Sediment Control measures to properly
protect the site. It is unlikely that perimeter control measures can be installed without
impacting the preservation areas. It is recommended that more distance be given between the
back of Buildings 5 and 6 and the Preservation area, consequently reducing the amount of
acreage in the Preservation area and impacting the bonus density. With enough space
provided to install them, proposed E &S measures are anticipated to reduce sediment -laden
runoff from leaving the site. Inspection and bonding by the County will monitor
maintenance of the erosion control facilities during construction. Proper stabilization and
maintenance will achieve long term stability.
4. "loss of aesthetic resource": The site plan shows the critical slopes to be within a "wooded
area of hardwood trees." The disturbance of these critical slopes involves the removal of this
existing vegetation.
5. "septic effluent ": The existing subdivision is served by public sewer and there are no septic
drainfields within the area of this disturbance.
No portion of this site plan is located inside the 100 -year flood plain area according to FEMA Maps,
dated 04 February 2005.
Based on the above review, the applicant can satisfactorily address the technical criteria for the
disturbance of critical slopes with the Final Grading and Erosion Control Plan, provided that sufficient
area is provided for perimeter controls. Also, terracing should be considered in areas of long steep
slopes. Accomplishment of these may result in the loss of some of the proposed Preservation area.
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