HomeMy WebLinkAboutSP201400005 Assessment 2014-01-171/17/2014
Capacity Assessment
Onsite Wastewater System 117
Regents School of Charlottesville .1 vltm- I. X59
0 010 6'5
1,
Physical Address: 3045 Ivy Road Charlottesville, VA 22903 `'
Mailing Address: PO Box 852 Keswick, Virginia 22947 ROFESS10
ATTN: VDH - Albemarle County
Assessment conducted by Old Dominion Engineering (ODE)
Increased Occupancy
The Regents School of Charlottesville is located in the Administration Building at the
Christian Aid Mission Ivy Road Campus (TM 59 -23G -119). The building is served by
its own separate drainfield (VDH Permit Number 101 -98- 0630). The Regents School of
Charlottesville wants to increase its occupancy (students and staff). Current occupancy is
83 students and 10 staff. Water meter readings were taken from November 6, 2013 to the
present.
Current Onsite Wastewater Treatment and Dispersal System
The onsite septic system consists of a 4200 gallon septic tank, a 5000 gallon flow
equalization tank, and 1920 sqft of drainfield. The permitted amount of flow equalized
effluent that can be pumped to the drainfield is 691 gallons per day.
Monitored Water Meter Readings
Water meter readings were done every school day by the staff of the Regents School.
Water usage was not recorded on the weekends or school holidays. The summary of the
water usage is presented below; the raw data is presented on the following page.
School Days
28
Other Usage Days
1
Total Usage Days
29
Total Water Usage
12630
Maximum Water Usage per Day
758
Minimum Water Usage per Day
236
Average Daily Usage (occupancy days)
436
Number of current occupants
93
Average Water Usage per Day per Occupant Equivalent
4.7
Maximum Daily Water Usage per Occupant Equivalent
8.2
Minimum Daily Water Usage per Occupant Equivalent
2.5
Median Daily Water Usage per Occupant Equivalent
4.5
Page 1 of 4 Old Dominion Engineering - 2036 Forest Drive - Waynesboro, VA 22980 - olddomeng @ntelos.net
1/17/2014
Date
Day
Water Meter Reading
(Gallon)
Daily Use
(GPD)
Weekly
Total
7 Day
Weekly
Average
Occupants
Daily Water
Usage per
Occupant
6- Nov -2013
Wednesday
42
93
7- Nov -2013
Thursday
462
420
93
4.5
8- Nov -2013
Friday
890
93
4.6
9- Nov -2013
Saturday
Break
93
10- Nov -2013
Sunday
Break
93
11- Nov -2013
Monday
1231
93
3.7
12- Nov -2013
Tuesday
1677
4
93
4.8
13- Nov -2013
Wednesday
2189
93
5.5
14- Nov -2013
Thursday
2707
518
93
5.6
15- Nov -2013
Friday
3063
356
2173
310
93
3.8
16- Nov -2013
Saturday
Break
633
93
6.8
17- Nov -2013
Sunday
Break
93
18- Nov -2013
Monday
4329
633
93
6.8
19- Nov -2013
Tuesday
4744
415
93
4.5
20- Nov -2013
Wednesday
5240
496
93
5.3
21- Nov -2013
Thursday
5649
409
93
4.4
22- Nov -2013
Friday
6035
386
2972
425
93
4.2
23- Nov -2013
Saturday
Break
93
24- Nov -2013
Sunday
Break
93
25- Nov -2013
Monday
Break
93
26- Nov -2013
Tuesday
Break
93
27- Nov -2013
Wednesday
Break
93
28- Nov -2013
Thursday
Break
93
29- Nov -2013
Friday
Break
93
30- Nov -2013
Saturday
Break
93
1- Dec -2013
Sunday
Break
93
2- Dec -2013
Monday
6517
E482
93
5.2
3- Dec -2013
Tuesday
7275
93
8.2
4- Dec -2013
Wednesday
7881
606
93
6.5
5- Dec -2013
Thursday
8250
369
93
4.0
6- Dec -2013
Friday
8618
368
2583
369
93
4.0
7- Dec -2013
Saturday
Break
93
8- Dec -2013
Sunday
Break
93
9- Dec -2013
Monday
8986
368
93
4.0
10- Dec -2013
Tuesday
9230
244
93
2.6
11- Dec -2013
Wednesday
9466
236
93
2.5
12- Dec -2013
Thursday
9831
365
93
3.9
13- Dec -2013
Friday
10237
406
1619
231
93
4.4
14- Dec -2013
Saturday
Break
93
15- Dec -2013
Sunday
Break
93
16- Dec -2013
Monday
10652
415
93
4.5
17- Dec -2013
Tuesday
10998
346
93
3.7
18- Dec -2013
Wednesday
11373
375
93
4.0
19- Dec -2013
Thursday
11867
494
93
5.3
20- Dec -2013
Friday
12230
363
1993
285
93
3.9
21- Dec -2013
Saturday
Break
to
5- Jan -2014
Sunday
Break
6- Jan -2014
Monday
12672
442
1 93
4.8
Note -Highlighted cell is estimated based upon total water usage measured over the time period.
The school was used for a church event on November 16, 2013. The water meter reading
on the following Monday was divided among the Monday and the preceding Saturday.
The school is used infrequently for church events. This water usage was considered in
the analysis.
Page 2 of 4 Old Dominion Engineering - 2036 Forest Drive - Waynesboro, VA 22980 - olddomeng @ntelos.net
1/17/2014
Measure Water usage per Occupant
The average water usage per occupant during the study period was 4.7 gpd. A design
usage per occupant of 6.0 gpd captures 86% of all individual daily readings and 100% of
the weekly average readings taken in the study period. This recorded water usage is
consistent with EPA estimates of 5 -17 gpd per student (Per EPA/625/R- 00/008 Onsite
Wastewater Treatment Systems Manual Table 3 -5 range of wastewater flow rates from a
school without cafeteria, gym, or showers). The flow equalization volume in the system
is large enough to easily equalize peak weekly flows over the week for the measured
flows.
Wastewater System Capacity for School Usage
4200 gallon septic tank capacity @ 2 day detention time
V 4,200gal - 2100 gpd
Q 0 2days gP
161 Occupant x 8.2 gpd/Occupant (peak) = 1320 gpd (OK)
Dra infield Capacity per Week at Septic Tank Effluent
691 gpd x 7 days = 4,837 gallons per week
Drainfield Capacity (5 Day Water Usage Flow Equalized over 7 Days)
4,837 gallons per week - 5 days per week water usage = 967.4 gpd
Maximum Occupancy of School based upon 63 gpd per occupant (Water Usage
Study Considering Weekly Flow Equalization)
967.4 gpd - 6.0 gpd/occupant = 161 occupants
Minimum and Recommended Flow Equalization Capacity Storage Volume
Minimum = [5 days X (967.4 gpd - 691 gpd)] = 1,382 gallons
Recommended = 1.5 x Minimum = 2,073 gallons
Actual Flow Equalization Capacity Storage Volume Required
5000 gallons - 250 gallons (emergency storage) - 650 gallons (wet well
pump cover) = 4100 gallons
The maximum occupancy of the school that the onsite wastewater and disposal system
can handle is 161.
Page 3 of 4 Old Dominion Engineering - 2036 Forest Drive - Waynesboro, VA 22980 - olddomeng @ntelos.net
1/17/2014
The wastewater effluent strength will not exceed residential strength for BOD or TSS.
The wastewater strength is estimated at <250 mg /l BOD /TSS.
The existing onsite wastewater system will be able to handle the anticipated wastewater
effluent strength and flows for upcoming school session in which occupancy is less than
or equal to 161.
ODE Recommendations
1. The school should continue to monitor and record the installed water meter
readings daily. These readings should be verified by a licensed Alternative Onsite
Waste Water Operator and submitted to the Health Department yearly with an
inspection report of the system.
Page 4 of 4 Old Dominion Engineering - 2036 Forest Drive - Waynesboro, VA 22980 - olddomeng @ntelos.net