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W Mifflin Sani Sew & Stormwater Auth Allegheny Cnty

Sewage treatment plant, major discharger, West Mifflin, Pennsylvania. NPDES permit PA0026506 expired Mar 31, 2025; its limits still apply. Last 12 months: over a limit once (last March 2026), 29 required values missing. Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: form A monthly (29 values), form Q quarterly (2 values)
Last report on file
June 2026
Oct 2024 – Sep 2025
0 values over a limit, 0 required values missing, 0 of 16 reports late

Last 12 months (Oct 1, 2025 – Sep 30, 2026)

Period endingParameterReportedLimit
March 2026pH, instantaneous minimum5.8 SU≥ 6 SU

Limits in force (38)

ParameterStatisticLimitMonths
Oxygen, dissolved [DO]instantaneous minimum≥ 5 mg/Lall year
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all year
BOD, 5-day, 20 deg. Cmonthly averagereport only (lb/d)all year
BOD, 5-day, 20 deg. Cdaily maximumreport only (lb/d)all year
pHinstantaneous minimum≥ 6 SUall year
pHinstantaneous maximum≤ 9 SUall year
Solids, total suspendedmonthly average≤ 30 mg/Lall year
Solids, total suspendedweekly average≤ 45 mg/Lall year
Solids, total suspendedinstantaneous maximum≤ 60 mg/Lall year
Solids, total suspendedmonthly average≤ 1001 lb/dall year
Solids, total suspendeddaily maximum≤ 1502 lb/dall year
Solids, total suspendedmonthly averagereport only (mg/L)all year
Solids, total suspendedmonthly averagereport only (lb/d)all year
Solids, total suspendeddaily maximumreport only (lb/d)all year
Nitrogen, total [as N]quarterly averagereport only (mg/L)all year
Nitrogen, ammonia total [as N]monthly average≤ 2 mg/LMay–Oct
Nitrogen, ammonia total [as N]monthly average≤ 3 mg/LJan, Feb, Mar, Apr, Nov, Dec
Nitrogen, ammonia total [as N]weekly average≤ 3 mg/LMay–Oct
Nitrogen, ammonia total [as N]weekly average≤ 4.5 mg/LJan, Feb, Mar, Apr, Nov, Dec
Nitrogen, ammonia total [as N]instantaneous maximum≤ 4 mg/LMay–Oct
Nitrogen, ammonia total [as N]instantaneous maximum≤ 6 mg/LJan, Feb, Mar, Apr, Nov, Dec
Nitrogen, ammonia total [as N]monthly average≤ 67 lb/dMay–Oct
Nitrogen, ammonia total [as N]monthly average≤ 100 lb/dJan, Feb, Mar, Apr, Nov, Dec
Nitrogen, ammonia total [as N]weekly average≤ 100 lb/dMay–Oct
Nitrogen, ammonia total [as N]weekly average≤ 150 lb/dJan, Feb, Mar, Apr, Nov, Dec
Phosphorus, total [as P]quarterly averagereport only (mg/L)all year
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all year
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year
Ultraviolet light transmittancedaily minimumreport only (%)all year
Coliform, fecal generalmonthly average≤ 2000 #/100mLJan, Feb, Mar, Apr, Oct, Nov, Dec
Coliform, fecal generalgeometric mean≤ 200 #/100mLMay–Sep
Coliform, fecal generalinstantaneous maximum≤ 10000 #/100mLJan, Feb, Mar, Apr, Oct, Nov, Dec
Coliform, fecal generalinstantaneous maximum≤ 1000 #/100mLMay–Sep
BOD, carbonaceous [5 day, 20 C]monthly average≤ 25 mg/Lall year
BOD, carbonaceous [5 day, 20 C]weekly average≤ 37.5 mg/Lall year
BOD, carbonaceous [5 day, 20 C]instantaneous maximum≤ 50 mg/Lall year
BOD, carbonaceous [5 day, 20 C]monthly average≤ 834 lb/dall year
BOD, carbonaceous [5 day, 20 C]daily maximum≤ 1251 lb/dall year

How strict are these limits?

Cited limits by parameter: Pennsylvania's rules and the federal ones.

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On EPA ECHO: Facility report · DMR history

Your permit document is the final word. As JSON: /api/v1/permits/PA0026506 · MCP: https://passage-data.com/mcp