Stormwater Pollution Prevention Plan - Phoenix Sky Harbor ...

Non-mining MSGP 2010 General Permit
8.M.5
Sector-Specific Benchmarks. (See also Part 6 of the permit.)
Subsector
(Facility discharges may be subject to
requirements for more than one
sector/subsector)
Subsector M1. Automobile Salvage Yards
(SIC 5015)
Table 8.M-1
Parameter
Total Suspended Solids (TSS)
Total Aluminum
Total Iron
Total Lead 1
Benchmark
Monitoring
Concentration
100 mg/L
0.75 mg/L
1.0 mg/L
Hardness Dependent
1 The benchmark values of some metals are dependent on water hardness. For these parameters,
permittees must determine the hardness of the receiving water (see Appendix D, “Calculating Hardness
in Receiving Waters for Hardness Dependent Metals,” for methodology), in accordance with Part 6.2.1.1,
to identify the applicable ‘hardness range’ for determining their benchmark value applicable to their
facility. The ranges occur in 25 mg/L increments. Hardness Dependent Benchmarks follow in the table
below:
Benchmark values based on hardness and receiving waterbody
Water Hardness Range
(mg/L)
For discharges to
perennial and
intermittent
waterbodies
Lead
(mg/L)
For discharges to
ephemeral
waterbodies
Lead
(mg/L)
0-25 0.014 0.0293
25-50 0.030 0.0636
50-75 0.047 0.0995
75-100 0.065 0.1363
100-125 0.082 0.1736
125-150 0.100 0.2113
150-175 0.118 0.2492
175-200 0.136 0.2873
200-225 0.154 0.3255
225-250 0.172 0.3637
250-275 0.190 0.4020
275-300 0.209 0.4402
300-325 0.227 0.4784
325-350 0.245 0.5166
350-375 0.263 0.5547
375-400 0.281 0.5927
Stormwater Discharges Associated with Industrial Activity – Sector M 58