Water Pollution Control Facility

Secondary Treatment 1995 2015
BOD5 to Secondary (lbs/d)(1)
Annual Average Daily 26,600 33,300
Maximum-Month Daily (2) 41,000 52,700
Maximum Day 58,800 70,400
Suspended Solids to Secondary (lbs/d)(1)
Annual Average Daily 18,900 25,500
Maximum-Month Daily (2) 31,900 43,900
Maximum Day 47,000 71,700
Anaerobic Selectors
Number 2 2
Compartments each 3 3
Size: Length (ft) 126 126
Width (ft) 21 21
Sidewater depth (ft) 19 19
Mixers
Number 12 12
Motor Horsepower 7.5 7.5
Detention time at average day (2) (minutes) 32 29
Aeration Basins
Number of tanks operating 6 6
Size: Length (ft) 216 216
Width (ft) 42.0 42.0
Sidewater depth (ft) 18 18
Basin Volume (cu ft) 163,300 163,300
Total Volume: (Mg): 7.33 7.33
(cu ft): 979,780 979,780
Aeration Equipment
Type Fine bubbled dif. air
Total number of diffusers 11,208 11,208
Total blank spaces for add’l diffusers 2,232 2,232
Blowers
Type Single stage centrifugal
Number (including one standby) 3 3
Design inlet capacity (scfm) 13,800 13,800
Motor horsepower per blower 800 800
Final Settling Tanks
Number Operating 6 6
Size: Length (ft) 250 250
Width (ft) (2 bays per tank) 50 50
Sidewater depth (ft) 15 15
Total Surface Area (sq ft) 75,500 75,500
Overflow Rate (gpd/sq ft)
Average Flow 353 395
Peak Flow (75 mgd) 1,000 1,000
Solids Loading (lbs/d/sq ft)
Peak Flow plus RAS Flow 25 30
Disinfection
Agent Sodium Hypochlorite
System Capacity @ 25 mg/l and high
groundwater season flow (lbs/d)		 7,400 8,700
System Pumping Capacity (gph) 360 360
Number of pumps (including one standby) 44
Nominal Dosage Secondary Effluent (mg/l)2-12 2-12
Chlorine Contact Tanks
Number 2 2
Size: Effective Length (ft) 613 613
Width (ft) 14.5 14.5
Sidewater depth 13 13
Total Volume (cu ft) 231,100 231,100
Minimum Detention Time
at peak flow of 75 mgd (min)		 33 33
Dechlorination Facility Sodium Bisulfite
Effluent Pumps
Number (including one standby) 4 4
Pumping Capacity (mgd) 25 25
Motor Horsepower 200 200
  1. Includes solids processing sidestreams
  2. High groundwater season
  3. For Maximum-Month Loadings during high groundwater season