|
Customers and service area
|
| |
System |
West Point |
South |
Vashon |
Carnation |
Brightwater |
|
|
34 local agencies
(includes 17 cities, 16 sewer districts, and the Muckleshoot Indian Tribe) |
-- |
-- |
1 sewer district |
City of Carnation |
-- |
|
Population Served (estimated)
|
1.5 million residents |
660,000
(varies summer to winter) |
610,000
(varies summer to winter) |
1,100
(based on census data) |
2,000 |
190,000 |
|
|
415 square miles |
105 square miles |
241 square miles |
660 acres
(by 2050) |
832 acres
(in city and surrounding Urban Growth Area) |
67 square miles |
|
Sewage treated
|
|
| |
System |
West Point |
South |
Vashon |
Carnation |
Brightwater |
|
Sewage Treated
(Volume expected in Average Rainfall Year)
|
About 180 mgd (average) |
96 mgd |
67 mgd |
0.12 mgd |
0.09 mgd |
17 mgd |
|
Sewage Treated (2012)
|
187.8 mgd |
102.2 mgd |
83.7 mgd
(9.0 mgd due to Brightwater effluent recycle and 74.7 mgd due to raw sewage) |
0.126 mgd |
0.090 mgd |
Averaged 10.8 mgd when sending effluent to South Plant until Oct. 31.
Averaged 11.4 mgd when discharging effluent to Puget Sound via effluent tunnel. |
|
|
-- |
-- |
26.46 million gallons |
-- |
-- |
-- |
|
Facilities and Equipment
|
|
| |
System |
West Point |
South |
Vashon |
Carnation |
Brightwater |
|
Treatment plants
|
5 |
West Point Treatment Plant,
Seattle |
South Treatment Plant,
Renton |
Vashon Treatment Plant,
Vashon Island |
Carnation Treatment Plant,
Carnation |
Brightwater Treatment Plant, Snohomish County north of Woodinville |
|
Pump Stations
|
42 |
-- |
-- |
4 |
-- |
1 |
|
Regulator Stations
|
-- |
19 |
-- |
-- |
-- |
-- |
|
CSO treatment facilities
|
4:
Alki, Carkeek, Mercer/Elliott West, Henderson/Norfolk |
-- |
-- |
-- |
-- |
-- |
|
King County sewer conveyance lines
|
about 389 miles |
-- |
-- |
3.2 miles |
1.6 miles |
-- |
|
Sewer pipe diameter
|
6 inches to 17 feet |
-- |
-- |
2.5 to 8 inches |
12 inches |
36 to 66 inches |
|
Outfalls, length and depth
|
-- |
3,600 ft long;
240 ft deep;
600 ft diffuser
(500 ft plus a 100-ft extension) |
10,000 ft long;
625 ft deep;
4 diffusers @ 500 ft L ea. |
2,850 ft long;
200 ft deep;
no diffuser |
Primary discharge: Chinook Bend Wetland Enhancement Project.
Backup: Snoqualmie River at Carnation Farm Road Bridge. |
2 parallel pipes 4,600 ft long
600 ft deep
2 diffusers @ 250 ft L ea |
|
Design criteria
|
|
| |
West Point |
South |
Vashon |
Carnation |
Brightwater |
|
Average wet-weather flow (non-storm):
This number is often used to describe the size of the treatment plants. It is based on average wet-season flow (November through April) but does not include extraordinarily large storms in the average. It is based on an average that does not show the maximum flows that can be handled at a plant.
|
133 mgd |
115 mgd |
0.26 mgd (est.) |
0.22 mgd |
30 mgd (2012-2016) |
|
Maximum monthly average flow
|
215 mgd |
144 mgd |
0.52 mgd |
0.27 mgd |
40.9 mgd (2012-2016) |
|
Average dry-weather flow
|
110 mgd |
96 mgd |
-- |
0.21 mgd |
25.2 mdg (2012-2016) |
|
Biological oxygen demand (BOD) influent loading (annual average)
|
168,000 lbs/day |
220,000 lbs/day |
526 lbs/day |
314 mg/L |
66.063 lbs/day (max month 2012-2016) |
|
Total suspended solids (TSS) influent loading (average annual)
|
181,000 lbs/day |
201,000 lbs/day |
526 lbs/day |
314 mg/L |
61.400 lbs/day (max month 2012-2016) |
|
Instantaneous maximum capacity:
Maximum flows that can be handled at the plants--often for short periods; some portions of these flows get minimal treatment.
|
440 mgd |
325 mgd |
1.14 mgd
(2.05 mgd with on-site storage) |
1.4 mgd |
130 mgd |
|
Permit information
|
|
| |
System |
West Point |
South |
Vashon |
Carnation |
Brightwater |
Permit (NPDES) renewal dates:
View permit limits (BOD, TSS, fecal coliform, chlorine residual) for each treatment plant.
|
-- |
NPDES permit 6/30/2014 |
NPDES permit 10/31/2014
Reclaimed Water permit 10/31/2014 |
NPDES permit 8/31/2016 |
River (NPDES) permit.
Administratively extended till new permit issued. New permit expected in late 2013.
Reclaimed Water permit 12/30/2013 |
NPDES permit 7/31/2016
Reclaimed Water permit 8/1/2016 |
|
Resource recovery
|
|
| |
System |
West Point |
South |
Vashon |
Carnation |
Brightwater |
|
Electricity produced annually
|
-- |
.194 million kilowatt hours |
1.105 million kilowatt hours |
-- |
-- |
-- |
|
Methane gas sold annually
(Both West Point & South Plant also use digester gas to power plant equipment, such as boilers and digesters)
|
-- |
Not applicable |
1.83 million therms |
-- |
-- |
-- |
|
|
117,934 wet tons
(or 28,108 dry tons) |
45,231 wet tons (or 12,568 dry tons @ 27.79% solids) |
60,802 wet tons (or 13,891 dry tons @ 22.85% solids)
Note: South Plant receives sewage sludge from Vashon and Carnation plants.
|
66,024 gallons
(about 20 dry tons of solids) of sewage sludge hauled to South Plant for further treatment |
557,419 gallons
(about 35 dry tons) of solids hauled to South Plant for treatment |
8,220 wet tons (or 1,591 dry tons @ 19.36%) |
|
|
About 324.75 million gallons used for landscape irrigation, wetland enhancement, industrial processes, heating/cooling |
192.5 million gallons |
95.5 million gallons
4.14 million gallons distributed to customers |
-- |
32.61 million gallons of reclaimed water to Chinook Bend wetland enhancement site |
0.003 million gallons distributed to the Environmental and Education Center in December 2011. |
