HomeMy WebLinkAboutSP201000044 Legacy Document 2011-11-16 (8)COLLINS r=Nc=iNmr- -,RiNG
July 29, 2010
William Fritz
County of .Albemarle
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, VA 22902
I, 800 E JEFFERSON CHARLOTTESVILLE VA 22902
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434 293 3719 PH 43429337191"X
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www.collins- englneertng.com
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The Granger Preliminary Site Plan - Request for Critical Slopes 'Wainer
Dear Bill:
Please allow this letter to serve as a formal request of a critical slope waiver for the Granger
project. Relief is sought from the critical slope requirements of Section 18 -4.2 of the
Albemarle County Zoning Ordinance, to facilitate the grading and construction
improvements associated with the proposed development.
This request accompanies the Granger Preliminary Site Plan submission, which depicts the
critical slope locations along the subject parcel TMP 07600- 00 -00- 02400. As shown within
the preliminary plan, there are areas with 25% or greater slopes that are proposed to be
disturbed as part of this project.
The following table summarizes the critical slope characteristics of the.subject parcel:
Total Project Area: 69.427 acres
Project Area
Total Project Area Critical Slopes: 17.4 acres
Total Project Area Critical Slope Impacts: 3.52 acres
Percentage Total Project Area Critical Slopes Impacted: 20%
The total area of critical slopes disturbed by the proposed development is 3.52 acres. The
previous design for this subdivision plat had an impact on 6.34 acres of critical slopes, so we
have nearly cut our impacts in half with an updated design that is more sensitive to critical
areas. The current impacts compose 20% of the 17.4 total acres of critical slopes that exist
on the property. Special attention has been given to the preservation of critical slopes in the
areas nearby streams running through the site. Some disturbance to critical slopes is due to
required stream crossing for this project, and the other critical slope impacts are for the
storm-water management facilities for the proposed by -tight subdivision. This development
has been designed to maintain and preserve large portions of existing trees on many of the
proposed lots to help limit run -off from the project and help preserve the aesthetic resources
of the site by maintaining these vegetative ground cover of mature canopy trees as much as
possible.
Development of this site would be unreasonably restricted by the requirements of Section
18 -4.2 of the Ordinance, specifically a stream crossing is needed to gain access to 20 of the
proposed lots. These lots necessitate an upgrade to a stream crossing on the northern
portion of the site. Because the Granger site is bounded by the interstate and a railroad track
a stream crossing is the only possibility for access.
The site contains several stormwater management facilities. For the eastern portion of the
site, the pond is located in areas of critical slope. This pond is necessary to catch site
drainage and prevent any harmful impacts to the surrounding streams. Grading is this area is
for. the installation of the pond. Other critical slope impacts are associated with the
stormwatet management ponds as shown on the preliminary plan.
18- 4.2.6c Access ways, public utility lines and appurtenances, stormwater management
facilities, and any other public facilities necessary to allow the use of the parcel shall not be
required to be located within a building site and shall not be subject to the requirements of
this section 4.2.2, provided that the applicant demonstrates that no reasonable alternative
location or alignment exists. The county engineer shall requite that protective and restorative
measures be installed and maintained as deemed necessary to insure that the development
will be consistent with the intent of section 4.2 of this chapter.
Below, the considerations of developing critical slopes as provided in the Zoning Ordinance
Section 18 -4.2 are addressed:
1. `ynovement of soil and 'rock" Critical slope impacts have been minimized in this
development plan, and we have paid careful attention to not disturb critical slopes in
the vicinity of waterways when at all possible. Erosion and sediment control
measures will be implemented to ensure that no construction runoff harms adjacent
areas.
2. "excessive stormwater ninoff" The development plan provides stormwater conveyance,
storage, and filtration via the proposed storm sewer and stormwater management
facilities. This facility shall serve as a sediment basin during the grading and
stabilization period of the project, and will eventually be converted to a stormwater
management facility to treat the run -off prior to its release.
3. "siltation of natural and man -made bodies of water ". The erosion and sediment control
plan for this project will take measures to ensure that stormwater runoff is captured
and treated before reaching natural and man -made bodies of water. These measures
will be inspected and bonded by the County to ensure their proper functioning and
continued stability.
4. `Voss of aesthetic resoaarce': There is no anticipated loss of aesthetic resources. Along
that border of the property, we are providing a tree buffer /preservation area to
mitigate any visual impacts. Large swaths of the wooded areas of this site will be
maintained. Nature trails will be provided along the creeks that run through the site.
5. `feptic ffluent'; This site is serviced by public sewer and will not release any septic
effluent to the surrounding environment.
The updated revisions to the Preliminary Subdivision Plat for the Granger development
show a significant reduction in impact to critical slopes. The proposed site development
protects. the existing woodland areas and a majority of the natural critical slopes, in a cluster
development design. The evidence provided herein demonstrates that the grading within
critical slopes on this project will have minimal impact to public health, safety, welfare, or
other considerations that might result from the disturbance of the critical slopes.
Thank you for your assistance in this matter; please do not hesitate to contact me for any
ad6loi nal inf6bnation pertaining to this waiver request.
Since ly,
SWptt oll ns, PE
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County of Albemarle
Department of Community Development
Memorandum
To: Megan Yaniglos, Current Development planning and zoning review
From: Phil Custer, Current Development engineering review
Date: 30 August 2011
Subject: Granger Preliminary Plat (SUB- 2010- 00119) 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:
Disturbances to critical slopes shown in this preliminary plat exist throughout the parcel. There is also
considerable disturbance shown on adjacent parcels which is necessary for the construction of Sunset Ave.
Extended north of the Moore's Creels stream crossing. The majority of the critical slope disturbance
occurs with the construction of Lot 69, stream crossing 1, Sunset Avenue Extended north of Moore's
Creek, and Pond 2. Other disturbance are scattered throughout the site and are needed for lot grading,
drainage pipes /channels, utility lines, and house construction.
Areas
Acres
Total site
69.4 acres approximately
Critical slopes
17.4 acres*
25% of site
Critical slopes disturbed
3.52 acres* .
120.2% of critical slopes
*These are the numbers provided by the applicant. However, the offsite work to construct Sunset Avenue
and Stribling north of Moore's Creek does not appear to be included in the applicant's request.
Exemptions to critical slopes waivers for driveways, roads and utilities without reasonable
alternative locations:
The disturbance necessary to construct the Sunset Avenue Connector is exempt from the prohibition to
disturb critical, slopes because any development of this parcel will require this connector road to be built to
the property line.
Stormwater management facilities may be considered exempt if there is no reasonable alternative to critical
slope disturbances. In most cases with this project, the alternative to the disturbance shown in this plan
regarding the construction of S WM facilities is a reduction to the total number of proposed lots. The
Planning Commission's review of the critical slope waiver should not consider the disturbance necessary
to construct the stormwater facilities shown on the plan to be exempt.
Similarly to the disturbance necessary to construct SWM facilities, public utilities may be considered
exempt if there is no reasonable alternative to the critical slope disturbances. The disturbances to critical
slopes shown in this plan for utility construction can be reduced or eliminated by a decrease in the number
of lots. The Planning Commission's review of the critical slope waiver should not consider the disturbance
necessary to construct the public utilities shown on the plan to be exempt.
Compliance with Zoning Ordinance 18 -4.2:
Albemarle County Community Development
Engineering Review comments
Page 2 of 2
"movement of soil and rock"
An erosion and sediment control plan will be required for the proposed disturbance. Developments of
this size will require sediment traps and basins along the stream buffer and floodplain. The stormwater
facilities as shown can likely be designed as a sediment basins and meet state ESC standards.
Sediment loss can be further minimized with a comprehensive, overlot grading plan.
"excessive stormwater runoff'
Stormwater management is required for this project. However, due to the size of the watershed, the
county engineer may look favorably on a detention waiver. In which case, the additional stormwater
runoff from the site will be insignificant when compared to the amount of water flowing through
Moore's Creek. Then again, the 1996 study of the Moore's Creek watershed noted the history of
flooding along this stream and advised against future detention waivers.
"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"
A significant portion of the disturbed slopes are shown on the county's open space plan.
"septic effluent"
This development will be serviced by public sewer.
Engineering Recommendation:
The construction of the Granger Property disturbs a significant amount of critical slopes. The plans seems
to encroach along the fringes of bands of critical slopes. If development were pulled slightly back a
considerable portion of critical slopes could be spared. In some cases, design changes to avoid critical
slope disturbances are obvious and should be made by the applicant. For instance, the pipe at the end of
Granger Way could be redirected to Pond 3 down the fill slope at the elbow of the alley since this area is
already being disturbed. Another example is the relocation of the sewer line in the middle of lots 22 -26
farther up the hill, above the band of critical slope, so the area in between is not disturbed by the
homebuilder or lot owner in the future.
The Planning Commission will need to weigh the benefits of the Granger application, primarily the
greenway dedication and the connector road against the disturbances to critical slopes. Should the
Planning Commission decide to approve the critical slope waiver request, engineering recommends a
condition be placed on the approval that requires the applicant to provide an overlot grading plan to be
approved with the road, ESC, and SWM plans so that the construction of each lot will be under the grading
permit of just one plan and that the applicant redesigns the aspects of the plan mentioned in the previous
paragraph. All of the standard aspects of an overlot grading plan condition/proffer should be duplicated
for this application.
file 1::2 csw P[3C' t:;ruigc:r Preliminary Plat (: SW doc