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Grand Strand Water & Sewer Authority

Sewage treatment plant, major discharger, Mullins, South Carolina. NPDES permit SC0029408 expired Oct 31, 2023; its limits still apply. Last 12 months: no values over a limit, 10 required values missing. Source: EPA ECHO, Oct 22, 2026.

Reports due
About 29 days after each period: form 1 monthly (31 values), form 2 quarterly
Last report on file
September 2026
Oct 2024 – Sep 2025
0 values over a limit, 13 required values missing, 1 of 16 reports late

Limits in force (38)

ParameterStatisticLimitMonths
Oxygen, dissolved [DO]minimum≥ 6 mg/Lall year
pHminimum≥ 6 SUall year
pHmaximum≤ 8.5 SUall year
Solids, total suspendedmonthly average≤ 30 mg/Lall year
Solids, total suspendedweekly average≤ 45 mg/Lall year
Solids, total suspendedmonthly average≤ 688 lb/dall year
Solids, total suspendedweekly average≤ 1032 lb/dall year
Nitrogen, ammonia total [as N]monthly average≤ 1.78 mg/LJan, Feb, Nov, Dec
Nitrogen, ammonia total [as N]monthly average≤ 1 mg/LMar–Oct
Nitrogen, ammonia total [as N]weekly average≤ 2.67 mg/LJan, Feb, Nov, Dec
Nitrogen, ammonia total [as N]weekly average≤ 1.5 mg/LMar–Oct
Nitrogen, ammonia total [as N]monthly average≤ 41 lb/dJan, Feb, Nov, Dec
Nitrogen, ammonia total [as N]monthly average≤ 23 lb/dMar–Oct
Nitrogen, ammonia total [as N]weekly average≤ 62 lb/dJan, Feb, Nov, Dec
Nitrogen, ammonia total [as N]weekly average≤ 35 lb/dMar–Oct
Zinc, total [as Zn]monthly average≤ .24 mg/Lall year
Zinc, total [as Zn]daily maximum≤ .24 mg/Lall year
Zinc, total [as Zn]monthly average≤ 5.5 lb/dall year
Zinc, total [as Zn]daily maximum≤ 5.5 lb/dall year
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all year
Flow, in conduit or thru treatment plantweekly averagereport only (MGD)all year
Chlorine, total residualmonthly average≤ .011 mg/Lall year
Chlorine, total residualdaily maximum≤ .019 mg/Lall year
Chlorine, total residualmonthly average≤ .25 lb/dall year
Chlorine, total residualdaily maximum≤ .44 lb/dall year
E. coli30-day geometric mean≤ 126 MPN/100mLall year
E. colidaily maximum≤ 349 MPN/100mLall year
E. coli30-day geometric mean≤ 126 MPN/100mLall year
E. colidaily maximum≤ 800 MPN/100mLall year
BOD, carbonaceous [5 day, 20 C]monthly average≤ 10 mg/Lall year
BOD, carbonaceous [5 day, 20 C]weekly average≤ 15 mg/Lall year
BOD, carbonaceous [5 day, 20 C]monthly average≤ 229 lb/dall year
BOD, carbonaceous [5 day, 20 C]weekly average≤ 344 lb/dall year
Solids, suspended percent removalmonthly average minimum≥ 85 %all year
Carbonaceous oxygen demand, % removalmonthly average minimum≥ 85 %all year
Carbonaceous oxygen demand, % removalmonthly average minimum≥ 85 %all year
%Effect Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average≤ 25 %all year
%Effect Static Renewal 7 Day Chronic Ceriodaphnia dubiadaily maximum≤ 40 %all year

How strict are these limits?

Cited limits by parameter: South Carolina'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/SC0029408 · MCP: https://passage-data.com/mcp