Akron Water Pollution Control Station No Feasible Alternative

Table 4-2
Secondary Treatment System Loadings
(Based on 1994 Baseline Year Data)
90 MGD 110 MGD 150 MGD 200 MGD
Raw BOD5 (mg/l) 108 100 80 70
Primary Effluent BOD5 (mg/l) 60 60 56 56
Aeration Basin Loading (lbs/day) 45,036 55,044 70,056 93,408
A.B. Unit Loading 1 (lbs./day/1,000 cf) 13.0 15.9 20.0 27.0
Final Settling Tank Surface Overflow Rate (SOR) 2
636 778 1,060 1,414
FST Solids Loading 3 (lbs./day/sf) 12.2 14.9 20.3 27.1
1 Aeration basin total volume = 3,444,000 cf
2 Final settling tank total surface area = 141,400 sf
3 Based on 15% RAS rate
Based on the above data, and projecting from 2006 Stress Test simulated results, it may be
possible to meet effluent parameters, with the likely exception of NH3-N, at flows exceeding 150
MGD. Aeration Basin and Final Settling Tank hydraulic limitations would need to be addressed.
Influent flow records for the established 1994 baseline year were reviewed to determine the
number of days flow exceeded the 110 MGD secondary treatment capacity, and the higher
capacities being reviewed in this report. The year 1994 data was also compared with Years
1995 to 2005 to further support use of 1994 data as the baseline year. A summary of these
reviews is presented in Tables 4-3 and 4-4.
Table 4-3
1994 Akron WPCS Influent Flow
Yearly Average MGD Maximum MGD Minimum MGD Secondary Bypass
Influent Days >110 22 Days >110 98 Days 120 17 Days >120 86 Days 130 12 Days >130 72 Days 170 4 Days >170 42 Days 210 2 Days >210 19 Days 275 0 Days