Allocation
Dividing the maximum allowable industrial loading for each pollutant across the permitted users. Uncontrollable domestic loading and the safety reserve come off the top first — what remains is the pool.
Permitted industrial users
12
1.00 MGD combined permitted flow
Allocation method
Uniform
same mg/L ceiling for every user
Safety reserve
10%
of each MAHL, held for growth
Over-allocated
2
cadmium · mercury
Cadmium and mercury are over-allocated.
Committed industrial loading stands at 164% and
118% of the maximum allowable at current permitted flows. Neither
can be allocated as it stands, and this screen will not smooth that away — either the binding
criterion changes upstream, or someone pretreats, and a compliance schedule belongs in the
submittal rather than a quiet adjustment to the limit.
Review the limits →
Loading allocation by pollutant
All loadings in lb/d · headroom is committed allocation against the MAIL
| Pollutant | MAHL | Uncontrollable | Reserve | Committed | Headroom | |
|---|---|---|---|---|---|---|
| CadmiumCdOver-allocated | 0.41 | 0.06 | 0.04 | 0.31 | 0.51 | |
| MercuryHgOver-allocated | 0.091 | 0.014 | 0.009 | 0.068 | 0.080 | |
| CopperCu | 20.02 | 2.03 | 2.00 | 15.98 | 12.84 | |
| ZincZn | 44.60 | 6.30 | 4.46 | 33.84 | 25.72 | |
| LeadPb | 4.85 | 0.51 | 0.49 | 3.85 | 1.69 | |
| NickelNi | 11.90 | 1.12 | 1.19 | 9.59 | 2.97 | |
| + 11 more pollutants, all committed below 70% of their MAIL | ||||||
The MAIL is what remains of the MAHL after uncontrollable domestic and
background loading and the 10% safety reserve come off the top.
Copper still has 3.14 lb/d uncommitted — roughly one more plating
shop's worth.
Industrial users
Permitted flows drive each user's share of the MAIL
| Industrial user | Category | Flow MGD | Share |
|---|---|---|---|
| MBMillbrook Brewing Co. | Food & beverage | 0.260 | 26.0% |
| APArclight Plating | Metal finishing | 0.180 | 18.0% |
| CRCedar Ridge Hospital | Institutional | 0.140 | 14.0% |
| NCNorthgate Circuits | Electronics | 0.115 | 11.5% |
| DLDelta Laundry Services | Industrial laundry | 0.095 | 9.5% |
| VDVale Dairy Processing | Food & beverage | 0.085 | 8.5% |
| HMHarbor Metal Works | Metal finishing | 0.070 | 7.0% |
| + 5 minor industrial users · 0.055 MGD combined · 5.5% share | |||
Under uniform concentration every user gets the same
1.916 mg/L copper ceiling regardless of size. Allocated loading
differs only because permitted flow differs.
How the math works
Worked for copper — the same arithmetic runs for every pollutant
- 1 Start from the MAHL The maximum allowable headworks loading, set by the binding criterion. 20.02 lb/d
- 2 Subtract uncontrollable sources Domestic and background loading no permit can control. −2.03 lb/d
- 3 Hold the safety reserve 10% of the MAHL, kept back for growth and uncertainty. −2.00 lb/d
- 4 What remains is the MAIL The maximum allowable industrial loading — the pool you divide. 15.98 lb/d
- 5 Divide by the method Uniform concentration: MAIL ÷ (1.00 MGD × 8.34) — the same ceiling for every user. Simplest to enforce, hardest to challenge as arbitrary. 1.916 mg/L