HomeMy WebLinkAboutSE202100012 Review Comments Critical Slope Waiver 2021-04-08ar
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County of Albemarle
Department of Community Development
Memorandum
To: Cameron Langille, Community Development Planning and Zoning Review
From: J. E. Anderson, PE, CE-II, Community Development Engineering Review
Date: April 8, 2021
Subject: SE202100012 — Boys & Girls Club/Driver's Ed — Critical Slopes Impact Review
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 slopes proposed to be impacted lie between Ivy Creek School to the south, and an existing
student driver education paved circuit to the north. 0.11 Ac. of critical slopes lie entirely within the driver
education course, and there is no impact to critical slopes within stream buffer, temporary or otherwise.
The slopes are currently stabilized with understory shrubs, groundcover and trees. The applicant proposes
to grade within critical slopes for construction of a building, athletic field, hard courts, stairs, parking and
site access. The site is served by public water and sewer. Construction includes a septic pump station
that requires applicant coordinate pump station and 4" force main design with VDH.
Areas
Acres
Total site
216.69 Ac.
Critical slopes disturbed
0.42 Ac.
0.19% of total site
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in image above is WPO (stream) buffer. areas are critical slopes.
Albemarle County Community Development
Engineering Review comments
Page 2 of 5
Approximate limits of project site shown by blue outline, above. —0.11 Ac. critical slopes lie within paved
circuit of the driver education course (red -shaded area).
Exemptions to critical slopes waivers for driveways, roads and utilities without reasonable
alternative locations: The proposed disturbance is not one of the listed exemptions and therefore a
waiver is required.
Albemarle County Community Development
Engineering Review comments
Page 3 of 5
Compliance with Zoning Ordinance 18-4.2.5(a)(1):
"rapid and/or large-scale movement of soil and rock"
Existing critical slopes are stable. Disturbance of critical slopes will entail cuttinglexcavating earth to
perform final grading, with sections of stairs, storm line and very limited portions of a building and
hard surface courts proposed to be constructed on critical slopes. Without precise calculation, and
excepting grading of critical slopes (no proposed grade is steeper than 2.5:1), Engineering estimates
design avoids 85-90% of critical slopes in the vicinity of buildings, parking, access, hard surface
courts, grass athletic field, and utility installation (sheets C4.1, C4.2). Avoidance strategies are
evident at a glance with final site plan sheets C4.0, C4.1, C4.2. Retaining walls are used sparingly.
In March 2020, Engineering supported a waiver request for 0.79 Ac. impact to critical slopes for this
project. Under relocated /redesigned project, impact to critical slopes is cut by half. 2.5:1 final slopes
may be stabilized with permanent ground cover that does not require mowing. During construction,
proper ESC measures (nearly approved with WPO202000051) are deemed adequate to minimize
chances of rapid and large-scale movement of soil and/or rock.
"excessive stormwater run-off'
The impacted critical slopes will be replaced with a combination of building, hard surface courts,
paved parking /site access, terrace, stairs (impervious), and athletic field, slopes, and landscape areas
(pervious). The existing driver education course (substantial pavement) will be demolished to make
way for boys and girls club improvements. Additional runoff resulting from the change in land cover
is mitigated by the extent of existing impervious driving circuit pavement to be demolished. A net
impervious increase of 0.26 Ac. increases storm runoff. New impervious areas are virtually all (flat)
rooftop, pavilion/decking or parking/access areas. The majority of runoff from these areas is detained
in two underground detention systems to ensure post -development runoff meets minimum standards
for channel and flood protection.
"siltation of natural and man-made bodies of water"
There are no nearby man-made bodies of water. A WPO buffer is in close proximity, and during
construction, a temporary ESC measure (ST3) encroaches approximately 25' within the buffer, but
remains 75-ft from stream centerline. This temporary ESC measure is designed for construction
phase. No permanent improvements except required stone discharge pipe are proposed for critical
slopes. The floodplain does not extend to this site. Grading of critical slopes results in disturbed areas
that would otherwise remain undisturbed. However, slopes to be impacted are approximately 0.42
Ac., or half the 0.79 Ac. impact recommended for approved in March 2020. Temporary, phased ESC
measures provide perimeter containment of sediment transport, and minimize exposure and potential
for sediment release from areas of disturbance.
"loss of aesthetic resources"
The critical slopes to be impacted are primarily located behind and downslope of a proposed building,
hard courts, terrace, athletic field, and areas presently woods. GIS shows critical slopes within the
paved student driver education course. This development presents higher aesthetic value than the
existing driver education course.
"in the event of septic system failure, a greater travel distance of septic effluent"
The development proposes a septic effluent pump station, though not on critical slopes. Septic
effluent is designed to flow by gravity to the pump station, then by 4" force main (FM) to an existing
FM. VDH review is required. VDH "may revoke or modify any [state] permit if, at a later date, it
finds that the system would threaten public health or the environment". Staff does not believe
disturbance of critical slopes would result in a greater travel distance of septic effluent in the event of
system failure, since the station serves only the boys and girls club and any upset condition requiring
oflline repair may reasonably be addressed by temporarily removing restrooms, etc., from service.
Albemarle County Community Development
Engineering Review comments
Page 4 of 5
The following are additional factors to be considered by the commission for this application (§ 18-
4.2.5(a)(3)):
The commission may grant a modification or waiver if it finds that the modification or waiver:
1) would not be detrimental to the public health, safety or welfare, to the orderly
development of the area, or to adjacent properties;
Staff does not find the waiver would be detrimental to the public health,
safety or welfare, to the orderly development of the area, or to adjacent
properties.
2) would not be contrary to sound engineering practices; and
Staff does not find this request to be contrary to sound engineering
practices.
3) at least one of the following:
a. Strict application of the requirements of section 4.2 would not forward the
purposes of this chapter or otherwise serve the public health, safety or welfare;
Staff supports this finding because slopes impacted are not integrated with
a more extensive slope network, are isolated, and are outside the WPO
buffer. Also, the boys and girls club will serve the public welfare,
especially given the pandemic's devastating impact on adolescent
socializing and learning opportunities.
b. Alternatives proposed by the developer or subdivider would satisfy the intent
and purposes of section 4.2 to at least an equivalent degree;
Staff supports this finding as an alternative design west on the same
school -owned parcel was reviewed and recommended for approval with
0.79 Ac. critical slope impact. This redesign reduces critical slope impact
fifty percent.
C. Due to the property's unusual size, topography, shape, location or other unusual
conditions, excluding the proprietary interest of the developer or subdivider,
prohibiting the disturbance of critical slopes would effectively prohibit or
unreasonably restrict the use of the property or would result in significant
degradation of the property or adjacent properties; or
The developer and this design sought alternative location that minimizes
impacts to critical slopes. To limit impact to slopes to a lesser degree or
prohibit any impact would, in staffs opinion, unreasonably restrict ACPS
partnership ability to team with Boys and Girls Club of Central Virginia
to provide facilities that advance educational opportunities for the youth of
Albemarle County.
d. Granting the modification or waiver would serve a public purpose of greater
import than would be served by strict application of the regulations sought to
be modified or waived.
Albemarle County Community Development
Engineering Review comments
Page 5 of 5
Staff supports this finding. Quoting Applicant's 2/10/21 letter: `The
proposed Boys and Girls Club facility would serve the public and students
who attend the surrounding public schools. The site layout is designed to
prioritize both the safety of the students and staff, as well as the
maintenance of the existing character and topography of the land.'
Based on the review above, there are no engineering concerns which should prohibit the disturbance of
the critical slopes as shown and engineering staff recommends approval of the Critical Slopes waiver
request.
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