HomeMy WebLinkAboutSDP200700075 CalculationsMount Calvary Baptist Church
Drain Area # I
Pre - Development
HYDRO tx.t
VERSION 2.2 t+ ++
Area Number C Area NO CA
1 0.900 0.130 0.117
2 0.300 0.570 0.171
Weighted Totals: 0.41 -1 0.700 0.288
Time of concentration = 5 min
Period Intensity Peak Flow
years) (in /hr) (cfs)
2 5.40 1.56
5 6.35 1.83
10 7.10 2.04
25 8.00 2.30
50 8.90 2.56
100 9.60 2.76
Post - Development
HYDRO tit+
VERSION 2.2 + * **
Area Number C Area (ac) CA
1 0.900 0.380 0.342
0.300 0.320 0.096
Weighted Totals: 0.626 0.700 0.438
Time of concentration= 5 min
Period Intensity Peak Flow
years) (in /hr) (cfs)
2 5.40 2.37
5 6-35 2.78
10 7.10 3.11
25 8.00 3.50
50 8.90 3.90
100 9.60 4.20
Drain Area #2
Pre - Development
Area Number
i
Weighted Totals
C Area (ac) CA
0.300 0.360 0.108
0.300 0.360 0.108
Time of concentration = 5 min
Period Intensity Peak Flow
years)in/hr)cfs)
2 5.40 0.58
5 6.35 0.69
10 7.10 0.77
25 8.00 0.86
50 8.90 0.96
100 9.60 1.04
Post - Development
Area Number C Area ac)CA
1 0.900 0.220 0.198
2 0.300 0.140 0.042
Weighted Totals:0.667 0.360 0.240
Time of concentration=5 min
Period Intensity Peak Flow
years)in /hr)cfs)
2 5.40 1.30
5 6.35 1.52
10 7.10 1.70
25 8.00 1.92
50 8.90 2.14
100 9.60 2.30
Short Version BMP Computations For Worksheets 2 - 6
Albemarle County Water Protection Ordinance: Modified Simple Method
Plan: Mount Calvary Baptist Church Water Resources Area:
Preparer: TM Date: 17- Sep -07
Project Drainage Area Designation DA #1
L storm pollutant export in pounds, L = [P(Pj)Rv /12 ] [ C(A)2.72 ]
Rv mean runoff coefficient, Rv = 0.05 + 0.009(1)
Pi small storm correction factor, 0.9
1 percent imperviousness
P annual precipitation, 43" in Albemarle
A project area in acres in subject drainage area, A = 0.70
C pollutant concentration, mg /I or ppm target phosphorus
f factor applied to RR
V required treatment volume in cy, 0.5" over imperv. area = A(1)43560(0.5/12)/27
RR required removal , L(post) - f x L(pre)
RR removal efficiency, RR100 /L(post)
Impervious Cover Computation (values in feet & square feet)
Item
Drinking Water Watershed
pre - development Area post - development
Roads Length Width subtotal Length Width
80 10 800 80
0 0 0 0
0 0
0 800
Driveways
and walks
Parking Lots
Gravel areas
Structures
Length Width no. subtotal Length Width no.
0 0 0 0 0 0
0 0 0 0 0 0
0 0
1 2 3 4 1 2
0
Area
Actively - grazed pasture &
yards and cultivated turf
Active crop land
Other Impervious Areas
Impervious Cover
3435
x 0.70 =
Area no. subtotal
600 0 0
1792 0 0
130 0 0
Area
0 x 0.08 =
Area
x 0.25 =
0 15360
Area
2404.5 x 0.70 =
Area no.
600
0
0
Area
0 0 x 0.08 =
Area
0 x 0.25 =
0
11%
I(pre)
Area
subtotal
10 800
0 0
0 0
0 800
subtotal
0 0
0 0
0 0
3 4
0 15360
0
subtotal
1 600
0 0
0 600
11"
0
55%
post)
Rv(post)V
1(pre)'Rv(pre)L(pre)L(post)RR RR
0.54 25.9
0.90 20%0.23 0.99 2.34 1.45
New Development For Development Areas, existing impervious cover <= 20 %)
0.35
C f 1(pre) "Rv(pre)L(pre)L(post)RR % RR Area Type
0.70 1.00 20%0.23 0.99 2.34 1.35 58%Development Area
0.35 1.00 0%0.14 0.31 1.17 0.86 73%Drinking Water Watersheds
0.40 1.00 1%0.14 0.36 1.34 0.98 73%Other Rural Land
min. values
Redevelopment (For Development Areas, existing impervious cover > 20 %)
C f 1(pre)'Rv(pre)L(pre)L(post)RR RR Area Type
0.70 0.90 20%0.23 0.99 2.34 1.45 62%Development Area
0.35 0.85 0%0.14 0.31 1.17 0.91 77%Drinking Water Watersheds
0.40 0.85 1%0.14 0.36 1.34 1.04 77%Other Rural Land
Interim Manual, Page 70 rev. 16 Feb 1999 GEB
Short Version BMP Computations For Worksheets 2 - 6
Albemarle County Water Protection Ordinance: Modified Simple Method
Plan: Mount Calvary Baptist Church Water Resources Area: Drinking Water Watershed
Preparer: TM Date: 17- Sep-07
Project Drainage Area Designation DA #2
L storm pollutant export in pounds, L = [P(Pj)Rv /12 ] [ C(A)2.72 ]
Rv mean runoff coefficient, Rv = 0.05 + 0.009(1)
Pi small storm correction factor, 0.9
1 percent imperviousness
P annual precipitation, 43" in Albemarle
A project area in acres in subject drainage area, A = 0.36
C pollutant concentration, mg /1 or ppm target phosphorus
f factor applied to RR
V required treatment volume in cy, 0.5" over imperv. area = A(1)43560(0.5/12)/27
RR required removal , L(post) - f x L(pre)
RR removal efficiency, RR100 /L(post)
Impervious Cover Computation (values in feet & square feet)
Item
pre - development Area post - development Area
Roads Length Width subtotal Length Width subtotal
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0
0 0 0 0
Driveways Length Width no. subtotal Length Width no. subtotal
and walks 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0
Parking Lots 1 2 3 4 1 2 3 4
0 0 9620 0 9620
Gravel areas Area 0 Area
x0.70= 0 x0.70=0
Structures Area no. subtotal Area no. subtotal
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
Actively - grazed pasture & Area Area
yards and cultivated turf 0 x 0.08 = 0 0 x 0.08 =0
Active crop land Area Area
x0.25= 0 x0.25=0
Other Impervious Areas
0 0
Impervious Cover 0%61%
I(pre)I(post)
Rv(post) V
0.60 14.8
New Development (For Development Areas, existing impervious cover <= 20 %)
C f I (pre) " Rv(pre) L(pre) L(post) RR % RR Area Type
0.70 1.00 20% 0.23 0.51 1.33 0.82 62%Development Area
0.35 1.00 0% 0.05 0.06 0.67 0.61 92%Drinking Water Watersheds
0.40 1.00 1% 0.06 0.07 076 0.69 90%Other Rural Land
min. values
Redevelopment (For Development Areas, existing impervious cover > 20 %)
C f I (pre) ` Rv(pre) L(pre) L(post) RR % RR Area Type
0.70 0.90 20% 0.23 0.51 1.33 0.87 66%Development Area
0.35 0.85 0% 0.05 0.06 0.67 0.62 93%Drinking Water Watersheds
0.40 0.85 1% 0.06 0.07 0.76 070 92%Other Rural Land
Interim Manual, Page 70 rev. 16 Feb 1999 GEB
EXCELSPREADSHEET
filename: ENTR -2 -LN
COMMERCIAL ENTRANCE WORKSHEET
FOR TWO -LANE HIGHWAYS
ENTRANCE LOCATION: Mount Calvary Baptist Church
KNOWN CRITERIA:
HIGHWAY POSTED SPEED (MPH) t 35 2
HIGHWAY TRAFFIC VOLUME (VPD) 1,200 2
FUNCT, CLASS. FACTOR (BELOW) 1 1
TRAFFIC GENERATED BY SITE (VPD) 30 0
See "Alin. St'ds. of Entrs. to State Highways"
for additional Entrance requirements
Set.: € ,sad Design Manual, Figure C -1 -1.20
Functional Classification Factors:
LOCAL W 0
SECONDARY COLLECTOR = 1
PRIMARY COLLECTOR = 2
MINOR ARTERIAL W 3
PRINCIPAL ARTERIAL W 4
NHS = 5
For UNPOSTED SECONDARY ROADS, Average
DESIGN SPECS:
LEFT TURN LANE x*
MIN. ENTR. RADIUS = 25`
REMARKS (Optional):
Running Speed may be entered, by approval
127 Highway Traffic Volume (VPD) must include
New" Traffic Generated by Site (VPD)
Note: Data MUST be entered in all Empty "Boxes"
Note: Use "Tab" Key to move to next "Box"
Note: Select Printer Icon to Print
F
TRANSITION TO LEFT TURN LANE *'
EXCELSPREADSHEET
filename: ENTR -2 -LN
COMMERCIAL ENTRANCE WORKSHEET
FOR TWO -LANE HIGHWAYS
ENTRANCE LOCATION: Mount Calvary Baptist Church
KNOWN CRITERIA:
HIGHWAY POSTED SPEED (MPH) 41 35 2
HIGHWAY TRAFFIC VOLUME (VPD)w 1,200 2
FUNCT. CLASS. FACTOR (BELOW) 2 2
TRAFFIC GENERATED BY SITE (VPD) 236 3
See "Min. St`ds, of Entrs. to State Highways"
for additional Entrance requirements
See Road Design € lanua €, Figure C -1-1€ 20
Functional Classification Factors:
LOCAL = 0
SECONDARY COLLECTOR m 1
PRIMARY COLLECTOR W 2
MINOR ARTERIAL W 3
PRINCIPAL ARTERIAL = 4
NHS W S
For UNPOSTED SECONDARY ROADS, Average
DESIGN SPECS:
LEFT TURD LADE "
MIN. ENTR. RADIUS = 25'
REMARKS (Optional):
Running Speed may be entered, by approval
7 Highway Traffic Volume (VPD) must include
New" Traffic Generated by Site (VPD)
Note: Data MUST be entered in all Empty "Boxes"
Note, Use "Tab" Key to move to next "Box"
Note, Select Printer Icon to Print
F
TRANSITION TO LEFT TURN LANE"
Dex A. Sanders
16102 Raccoon Ford Road • Culpeper, Virginia 22701
Tel 540.829.2590 • Fax 540.829.2591 • dexarchitecuulearthlink.net
16 May 2006
Project# 0417
TO Amy Ransom Arnold
Planner, Rural Area
County of Albemarle
RE: SP -06 -06 Mount Calvary Baptist Church
WAIVER REQUESTS & PARKING STUDY
On behalf of the Mount Calvary Baptist Church, we are requesting that the County grant the
following waiver requests for the proposed development:
Please waive section 18- 4.12.15a to permit gravel parking for weekly use. Eliminating
impervious surfacing will help reduce storm water runoff flow and reduce the scope of
BMP work required in the limited space available.
Please waive the County requirement for curbs along parking and travelways for this
existing use in a rural area.
Please waive the requirement for a 20' wide travelway serving the rear overflow parking
area. The 20' width is not available on this site through the existing cemetery.
Additionally, we would request that the County not require the commercial setbacks and
buffers of Section 21 as a condition of this use permit.
The church would request that the existing 30' prescriptive use easement remain along State
Route 738.
In order to construct the proposed new building, the Owner may need to request a modification
to the existing East setback line to allow an exterior emergency egress stair to cross the 15'
building setback line.
Also, we would ask that the Board of Supervisors allow five (5) years for the church to start
construction of the new use.
PARKING STUDY
Under section 4.12.6, the zoning administrator determines the number of parking spaces
required for churches in rural areas of the comprehensive plan. Please consider the following
data:
Proposed Sanctuary = 1,681 SF
Congregational Pew Seating = 176 (by code)
Choir Pew Seating = 24 (by code)
Total Sanctuary Capacity = 200 (by code)
Maximum Practical Seating Capacity = 168 (@ 22" per person)
Note: Pew seating based on a historic use of 7B" per person per IBC2003. This represents
absolute maximum seating capacity and is difficult to achieve in practice. Today, north
American adults require closer to 24 " per person.
Proposed Fellowship Dining Hall = 1,681 SF / 15 = 112 seats for tables and chairs.
Historically, church parking calculations are based on sanctuary seating only as both the
Sanctuary and Fellowship areas are not occupied at the same time in smaller church facilities.
It is a well documented pattern in church growth that once Sanctuary seating reaches about
80% full, growth reaches a plateau. It is very difficult to practically maintain 100% capacity
Sunday after Sunday. People just don't like to be that crowded.
As design professionals very experienced with church projects in the area, we would calculate
required parking spaces for a 200 person occupancy at between 2.5 and 3 spaces per person,
with 2.8 spaces per person being very typical for many rural congregations where 1/3 or more of
the congregation consists of families with children.
Smaller congregations with attendance under 50 persons often require closer to 2 spaces per
person.
We would project parking needs for the proposed facility as follows:
Maximum sustainable Sunday parking for 134 persons = 134 / 2.8 = 48 spaces
All regular spaces full w/ 14 in overflow)
Maximum normal peak parking Sundays for 168 persons = 168 / 2.8 = 60 spaces
All spaces full - site capacity on Easter & anniversary Sundays)
Special Event parking (funeral) for 200 persons = 200 / 2.8 = 71 spaces
All spaces full w/ parking along the street)
Below is a recent survey of actual use over a four week period:
Mt. Calvary Baptist
Church
Parking Study
Date Cars Attendance Comments
4/23/2006 18 30
4/30/2006 No Church
5/7/2006 25 60
5/14/2006 25 44
Please do not hesitate to contact us with any questions about this information.
Sincerely,
Dex A. Sanders, AIA