UC(t) = UC(n)
+ UC(an)
| |||
Where
| |||
UC(t)
|
=
|
Total user charge for POTW operation and maintenance
| |
UC(n)
|
=
|
User charge associated with normal sewage
| |
UC(an)
|
=
|
User charge associated with abnormal sewage
| |
UC(n)
|
=
|
OM X (OQ/100) X (QIA/QA)
| |
UC(an)
|
=
|
OM {[OB/100 X (BIA-Bn)/BA] + [OS/100 X (SIA-Sn)/SA]
+ [OP/100 X (PIA-Pn)/PA] + [ONH/100 X (NHIA-NHn)/NHA] + [OTK/100 X
(TKIA-TKn)/TKA]}
| |
Where:
| |||
OM
|
=
|
Total annual POTW operation and maintenance
and debt service costs
| |
OQ
|
=
|
Percentage of OM attributable to flow (Q)
| |
OB
|
=
|
Percentage of OM attributable to BOD5
| |
OS
|
=
|
Percentage of OM attributable to suspended solids
| |
OP
|
=
|
Percentage of OM attributable to total phosphorus
| |
ONH
|
=
|
Percentage of OM attributable to ammonia
| |
OTK
|
=
|
Percentage of OM attributable to total Kjeldahl
nitrogen
| |
QIA
|
=
|
Average daily flow rate (MGD) from discharger
| |
BIA
|
=
|
Average daily BOD5 loading (LB/DAY) from discharger
| |
SIA
|
=
|
Average daily suspended solids loading (LB/DAY)
from discharger
| |
PIA
|
=
|
Average daily total phosphorus loading (LB/DAY)
from discharger
| |
NHIA
|
=
|
Average daily ammonia loading (LB N/DAY) from
discharger
| |
TKIA
|
=
|
Average daily total Kjeldahl nitrogen loading
(LB N/DAY) from discharger
| |
QA
|
=
|
Average daily flow rate (MGD) at the POTW treatment
plant
| |
BA
|
=
|
Average daily BOD5 loading (LB/DAY) at the POTW
treatment plant
| |
SA
|
=
|
Average daily suspended solids loading (LB/DAY)
at the POTW treatment plant
| |
PA
|
=
|
Average daily total phosphorus loading (LB/DAY)
at the POTW treatment plant
| |
NHA
|
=
|
Average daily total ammonia loading (LB N/DAY)
at the POTW treatment plant
| |
TKA
|
=
|
Average daily total Kjeldahl nitrogen loading
(LB N/DAY) at the POTW treatment plant
| |
Bn
|
=
|
BOD5 loading (LB/DAY) in discharge if it were
normal sewage
| |
Sn
|
=
|
Suspended solids loading (LB/DAY) in discharge
if it were normal sewage
| |
Pn
|
=
|
Total phosphorus loading (LB/DAY) in discharge
if it were normal sewage
| |
NHn
|
=
|
Ammonia loading (LB N/DAY) in discharge if it
were normal sewage
| |
TKn
|
=
|
Total Kjeldahl nitrogen loading (LB N/DAY) in
discharge if it were normal sewage
|
NOTE: If any difference terms in the equation
above is negative, then that portion of the equation shall not be
used, that is, the difference shall be set to zero when it is negative.
| |
NOTE: All averages are arithmetic averages determined
from available data during the billing period.
|