HomeMy WebLinkAboutSP201500032 Assessment - Groundwater 2015-12-22Re -store N Station Phase H Amendment
SP2015 —00032
Revised Groundwater Recharge Calculations
Based upon Existing and Proposed Site Development
(Concept Plan dated 1214/2015)
Prepared by Old Dominion Engineering - 2/18/16
Annual Precipitation - 46 inches
Site Area - 4.06 Acres (1.4978 Acres Pervious)
Page 1 of 2
Median Recharge per USGS Regional Aquifer System Analysis - 13 inches
Pervious Area Recharge - 1.4978 acres x 13 "/yr = 1,449 gpd
Rainwater Harvesting Recharge* - 7,075 sgft x 46"/yr x.95 = 528 gpd
Storm Water Management Practices** - 2.3998 acres x 13"/yr = 2,321 gpd
Daily Groundwater Recharge from Precipitation - 4,298 gpd
Estimated Groundwater Withdrawal - 1,625 GPD
Long Term Groundwater Recharge Due to Onsite Dispersal*** - 1,544 GPD
Estimated Total Long Term Groundwater Recharge - 5,842 GPD
The estimated long term ground water recharge at the site is 5,842 gpd and the estimated
groundwater withdrawal is 1,625 gpd.
It is not anticipated that groundwater withdrawal of this magnitude will impact
neighboring wells or general groundwater supplies. Furthermore, the proposed
groundwater usage does not pose a threat of groundwater contamination under normal
circumstances.
Notes:
* Rainwater harvesting is being planned for the rooftops of the existing building (2775
sgft) and 4300 sgft of the new building. Rainwater harvesting will be used for all
pervious area grass and landscaping (including tree) watering. Estimated recharge at
95% of 46" precipitation per year.
** The site will use Storm Water Management Practices utilizing underground detention
with outlet control to throttle discharge to pre developed conditions. The underground
detention will utilize an open bottom storage reservoir which will allow infiltration into
Old Dominion Engineering - 2036 Forest Drive Waynesboro, VA 22980. 540-942-5600 • olddomeng@ntelos.net
Page 2 of 2
the ground. Hayesville soils are very permeable at in creasing depths. ODE is estimating
these areas to recharge at a rate similar to USGS Regional Aquifer Study (13" per year).
It actually could be a greater percentage of recharge due to increased soil permeabilities
at the projected depth of storm water detention.
*** One of the main advantages of an onsite treatment and dispersal waste water system
is that the water removed from the aquifer for use is treated and dispersed in the same
general immediate vicinity. The vast majority of water usage (>95%) is eventually
returned to the aquifer as treated effluent and will serve as additional ground water
recharge. The estimated water usage at the site is 1,625 GPD. Long term recharge from
treated effluent will approach 95% of withdrawn water or 1,544 GPD.
Old Dominion Engineering • 2036 Forest Drive Waynesboro, VA 22980.540-942-5600 • olddomeng@ntelos.net
January 19, 2010
Jo ffiggins
Project Development, LLC
2564 Mount Torrey Raod
L"WhU st, Virginia 22952
RE: Restore N' Station Tier III Addendum
Dear MS. Biggins,
In the Tier M Groundwater Assessment and Groundwater Management Pian for Re.
Stcltse'N Station (TAP 558-1) dated October 3, 2008 we estimated the groundwater
recharge at 2,115 gallons per day and the well water withdrawal rate at 725 gallons per
day.
You have requested a modification to our report considering a new well water withdrawal
rate eornespoelding to the VDH approved septic system design rate of 1600 gallons per
day )" or Wi WXin1MlY I gallon per mute (gpm). T lis memo serves as an
addendum to our original Tier III Groundwater Assessment.
Please consider the following:
1. Our anginal estimate ofrecharge was estimated very conservatively at 2115 gpd.
In reality the actual recharge rate will exceed this estimate.
2. Our original estimate also did not include the 725 gpd water usage as a recharge.
The vast majority of the well water used on the site will be treated then disposed
in the drainfield and ultimately serge as recharge.
3. Design loading rates for drainfields include a safety factor in excess of the
lTjcted groundwsw usage rate. In Virginia, this Amr is typically I.4 times
the actual average water usage rate. We would anticipate the achual average water
usage will be close to 1,143 gpd.
4. Even with the withdrawal rate of 1600 gpd, the number is still below estimated
average recharge of 2115 gpd.
In our best professional opinion, it is thought that a groundwater withdrawal of 1600 gpd
(aPPmldmately 1 gPm) or leas will not i[rnpact the miming g yells an adjoining parcels or
elsewhere in terms of groundwater supply. Furthermore, this usage does not pose threats
ofWa ndwater contamination under normal circumstances.
Umitaliens
Tie work performed in conjunction with this project, and the data developed, are
intended as a ducription of avail" infornaation, fly accepted industry standards
118 Buckingham Circle, Charlottesville, VA 22903 1 434.923,4888 I Fax 434.923.0555 1 www.truenorthenv_com
Addendum to Tier III True North Environmental
Restore `N° Station anua 19 2010
were used in the preparation of this report. Stated opinions and conclusions are not
intended as a guarantee and the only reliable way to confirm that a sustainable
groundwater resource is present is to drill and test a groundwater well for quantity and
quality.
True North Environmental appreciates the opportunity to be of service to you with this
project. If you have any questions, please call me at your earliest convenience.
Sincerely,
Vincent Day, PG
Geologist/Principal
2
Michael Craun, PE
Old Dominion Engineering
Re-Store'N Station
Tier 3 Groundwater Assessment
Groundwater Management Plan
TMP 55B -i
Crozet, Virginia
October 3, 2008
Prepared for:
Jeffries II, LLC
P.O. Box 910
Crozet, VA 22932
Submitted by:
Old Dominion Engineering
2036 Forest Drive
Waynesboro, VA 22980
Prepared by:
Nick H. Evans PhD, CPG
Vincent Day
Key Findings
Hydrogeologic unit: Piedmont Foothills
Groundwater availability zone: Ill --Class 2 (medium relative availability)
Estimated daily groundwater withdrawal: 725 gallons
Estimated daily groundwater recharge to site: 2115 gallons
Site within groundwater sensitivity zone? Yes:
Contamination threats on record: 4 documented leaking underground storage
tank (!_UST) sites within 9000 fleet of the property
Additional contaminant threats observed in field reconnaissance? None
Hydrogeologic conditions favorable to proposed use? Yes
Anticipated impar of proposed use on existing users: None
Groundwater management plan: Implement runoff -neutral site development as
practicable.
Site Overview
The proposed development comprises about 4 acres located on the south side of
US 250 approximately 0.70 miles east of Route 64 (Figure 1) and is situated
entirely within the Stockton Creek watershed_ There are no streams on the
property; however, the property drains to the south into a swale that eventually
flows into an unnamed tributary of Stockton Creek. There is about 25 feet of relief
on the parcel. Land cover on the parcel is open field with mixed grasses and
weeds (image, below).
Land use on adjoining parcels
s residential and light
commercial business. A
convenience store is located
directly across Route 250,
north of the site. The Moose
Lodge is located on the
adjoining parcel to the west.
Adjacent land to the south is
occupied by residential
dwellings. The adjoining
Property to the east is occupied
by a tree service company.
The applicant proposes to construct a convenience store and gas station. This
facility would be served by a transient noncommunity water supply well, which
must be permitted in accordance with Virginia Health Department (VDH), Division
of Drinking Water. According to the project engineers, water consumption is
estimated to be approximately 725 gallons per day (documentation attached). A
site plan showing the proposed development layout and approximate land
disturbance is attached to this report. Runoff from the site will be controlled by
standard stonmwater management practices.
Hydrogeologic Asseswwrit
Bedr I* geokmry
The parcel is situated within a bedrock fonnabon described as bla*-muse ovde
leucogranite gneiss on the 1993 Geologic Map of Virginia (Figure 2). This falls
within the Piedmont Foothills hydrogeokoc unit, as defined in the Albemarle
County Hydrogeologic Assessment Summary Report of 2003, with Class 2
(medium) relative groundwater availability.
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Bedrock fracture densBy and water well productivh
The bedrock underlying this property does not contain primary intergranutar
porosity through which groundwater might flow. Instead, groundwater flow is
confined to bedrock fractures and fissures.
No significant linear features, fracture traces or structural features were identified
on air photos or otter maps in this study that would be useful indicators of
bedrock fracture orientation on this parcel. No bedrock exposures were
observed on the property during field reconnaissance. In the absence of good
bedrock exposures with which to directly observe bedrock fractures, the yields of
randomly -sited water wells can be used as a proxy for fracture density. Table 1
summarizes data from 52 wells in the current county database that were
constructed in the same bedrock formation as underlies this property.
Ta 1: Domeaft water weii st'afsifcs "m Albemarle CcwTft datWM&
me Id tate Well ��t �
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fi€n: 7EQmcoaranle enemamaximum:mox:10
2
F52
There are ten wells in the Albemarle County database that are within 25M feet of
the Property (Figure 3). Data from those wells are reported in Table 2.
Taw 2: Gagt Jor WVAS
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Overall, the data indicate that local biotite-muscovite leucocratic gr eiss bedrock
is favorable for groundwater development in terms of fracture density. However,
the success of a water well drilled at a given locafion still depends on whether or
not the well intersects water -bearing fractures. A dry hole results it no water -
bearing fractures are encountered at the chosen drilling site.
Solis and saurolite
According to published soils mapping (USDA Soil Conservation Service, Soil
Survey of Albemarle County, 1985), the site is underlain by two valants of the
Hayesville Loam (37B & 37C) and the Braddock Loam (7B) (Figure 4).
Hayesville soils are deep, well drained soils weathered from the gneissic parent
material. These soils occupy the side slopes of the site. Permeat; ility and
available water capacity are moderate. Surface runoff is medium and erosion
hazard is moderate. Shrink -swell potential is low.
Braddock soils are deep, well drained and weathered from alluvial fan deposits
that capped the residual underlying soils and saprolite. Petmeabili~y and
available crater capacity are moderate. Surface runoff is medium and erosion
hazard is moderate. Shrink -swell potential is moderate
The soils on site have the potential to contribute favorably to groundwater
recharge where land cover does not inhibit infiltration of rainwater.
Figure 4: Sale mapping it aloe vAdnity of TMp 5513-1
368: Hayesvfe ban .
2-7%slope
37C3. HaysevAe darn roam,
7 -15% slope
7B: Braddock loam,
2 - 7% slope
=0W LLSarp�naMatA7LIII VR
SW Gaarrr� Swvivra, , a► Sirvry
esaerr 0% Como, Yaps, IM
Groundwater flow„, recharge and discharge
The property is situated immediately south of a drainage divide between
Lickinghole Creek drainage to the north, and Stockton Creek to the south (Figure
5). Groundwater flow across the parcel is estimated to be generally in a
southerly direction. Ultimately, groundwater at shallow levels discharges Into an
unnamed tributary of Stockton Creek on adjoining parcels to the south, and into
Stockton Creek proper.
Groundwater sensitivity
Contaminant threats
The proposed development does coincide with areas of recognized groundwater
sensitivity according to Albemarle County studies and databases t tat were
assembled during the 2003 Albemar a County Hydrogeologic Assessment,
Phase 11 (Figure 6).
There are 4 leaking underground storage tank (LUST) sites within 1000 feet of
the property (fable 3). Due to the proximity of these LUST sites, the applicant
will need to test the well for presence of volatile organic compounds (VCC) in
accordance with Albermarle County ordinance 06-E(l) prior to issuance of a
building permit
Table 3: LUST 4hn within 2000 !fit of TMP 55 -BI l-ource= ViWriia DEO datahacwi
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2562
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38.04953965
-78.70965397
5995 Rwfth GWO T pka
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-78.71274657
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5128 i 2288
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36.04942562
78.71722149
6254 #iill = Ln
There are approximately 29 existing drainfrelds, locations inferred from air photos
and field reconnaissance, within 2500 feet of the proposed development (Figure
3). Few if any of these are up hydrologic gradient from ffm property, and none
are considered to pose contaminant threats to the property under iormal
circumstances.
Threats to existing users„ of groundwater
The proposed development antickiates using a maximum of 725 gaiions per day
in kitchen and bath facilities (documentation attached). This proposed
withdrawal of groundwater is not consumptive, to the extent that v'rtually all of
this water will be returned to the ground as recharge through a dreinfield.
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A conservative estimate of groundwater recharge for the site is on the order of
2115 gallons per day (calculations below). Available recharge is more than
adequate to supply the proposed withdrawal of 725 gallons per day.
It is not anticipated that groundwater withdrawal of this magnitude MIl impact
existing wells on adjoining parcels or elsewhere in terms of groundwater supply
The proposed use does not pose threats of groundwater contamination under
normal circumstances.
Water budoet estimate for site
Annual precipitation: 46 inches
Conservative estimate for percentage of precipitation contributing to groundwater
recharge: 15%
Annual groundwater recharge: 6.9 inches
Daily groundwater recharge: .0 189 inches = .0016 feet
Daily recharge per acre: .0016 feet X 43560 square feet per acre = 69.7 cubic
feet
Gallons recharge per day per acre: 69.76 cubic feet X 7.48 gallons per cubic
foot = 521 gallons per day per acre
Gallons per day recharge over entire site: 521 gallons per acre X 4.06 acres=
2115 gallons per day
Predicted groundwater withdrawal on site: 725 gallons per day
Reserve welflield
If the primary well fails due to contamination or lack of water, it will be necessary
to develop another water source. The options for locating a second well will be
limited by the size of the parcel and required set -barks from drainfields, parking
lots etc.
Dedicated Monitoring well
Due to the small size of the property, this would probably not be an appropriate
location for installation of a dedicated monitoring well.
Groundwater management plan
The proposed development will seek to minimize degrading groundwater
recharge by implementing runoff -neutral site design and storm water
management strategies that minimize offsite runoff.
Submitted by Nicholas H.
October 3, 2008
CPG # 2801001041
CePARTIrlEW OF PROFESSRML, AND OCCUPATIONAL REGULATIO 4
COMMONWEALTH OF VIRG94A
=W VAW 81ftd BMOK, INCh gond, VA
{U6-91-2009 TONOMM t soar W4" 28(1 1 001041
BOARD FOR GEOLOGY
CERTIFIED AS A PROFESSIONAL GEOLOGIST
NICHOLAS H EVAWS
4609 BURNLEY STATION ROAD ,
BARBOURSVILLE, VA 2.2923
�� �r r n..oa Dloeaor
rmmwmamroemum "mm ""m CK~
—__ . — —
Old Dominion Engineering
October 3, 2008
Josh Rubinstein., Groundwater -Manager
Albemarle County Community Development Office
401 Wlstire Road, North Wing
Charlottesville, VA 22902-4595
SUBJECT RE-STORE'N STATION ESTIMATED WATER USAGE
Property Owner: Jeffries II, LLC
Property Address: 6115 Rockfish Gap Tnpk, Crozet, '%'A
Acreage: 4.06 acres, TM 55B-1
Albemarle County
Psnperry Use
The proposed use for the property is a 6000 square foot convenience store and deli with gis pumps.
Avenge Daddy 'Wear U*Vc
Water usage data vats obtained for five similar facdides. Each of them have a convenience store, deli and gas
pumps, Based on this dam, the average water usage was 725 gpd. The facility most simile- to the Ice-Stom'N
Station m terms of size and location is the Brownville Marltet whose average water ung-. was 648 gpd.
However, for the ReStore'Ai Station, the mote comprehensive average of 725 gpd will be used. This water
usage is far less them 2000 gallons per dap. A Tier III Groundwater Assessment is adequate for the proposed
project and no special use permit will be required.
Shown below is the actual water usage data and the locations of the similar fac iliries.
Average w9ter usage of all favlities is 2L750 gallons per month or 7725 Moms pt -r .jay.
GAS STATIONS WITH CONVENIENCE AND FOOD TAKE OUT SERVICE
Water ta" In pions ! month
01148
Lib"
Shen
Sham
SP {RoWnj
Brawmvilte
(RM 3 AM30t Itdj
(RT29 S GnwnW ri
(RT250 Frm B Wp)
FT250
madtat
Nov -07
20.200
24,100
18,500
2)1300
16,000
Oct -07
24,300
22,100
29,500
21,100
17,600
Sap -07
21,300
19,600
23.100
23,3XO
2244
Aug -07
23.000
27,600
27.800
23.900
19.400
Jul -07
22.400
23,100
18.500
24,900
19.800
Jun -07
28.900
26,300
13.700
23,300
22,300
May -07
26.000
28,500
14AW
MOO
KIN
A"7
23,300
29AM
18.400
19.200
21,480
MW -07
14,900
23,588
15,800
22.000
20.000
Fab -07
15.800
23,588
23,100
' 8:309
16.000
Jan.87
17,200
22.9M
16.900
:4,909
16.600
DOC -06
192M
30.700
16.300
.4.200
Ave Galt Month
21,542
24,6x3
19,650
121458
18418
Average w9ter usage of all favlities is 2L750 gallons per month or 7725 Moms pt -r .jay.
-2— October 3, 2008
-Me water used it the facility w$1 be for food preparation and sanitary uses. Virtually all wa xr used in this
facility wilt he returned to the Site as treated wastewater effluent into the onsite wastmmtw , lisposal system and
ul6=tely for groundwater recb2zgc.
f
Sincerely,
F r
Midnel Craun PE
Old Dominion Engineenng
2036 Forest Drive • Waynesboro, 3'A 22980
PHONE (540) 942-5600 - FAX (540) 213-0297
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