Caseyville Township West STP
O Fallon, IL 62269 · Saint Clair County · Publicly Owned Treatment Works
- Average flow
- 0.49 MGD
- Design flow
- 1.96 MGD
- NPDES permit
- IL0023043
- Effective
- Permit expires
- January 2030
- Population served
- 4,979
- CWNS 2022
Caseyville Township West STP is a publicly owned wastewater treatment works in O Fallon, Saint Clair County, Illinois treating an average of 0.49 million gallons per day against a permitted design capacity of 1.96 MGD, serving about 4,979 residents. It discharges under NPDES permit IL0023043 (effective), which expires in January 2030, with 0 recorded violations in the last three years.
Treatment technology
One treatment structure or unit process identified at Caseyville Township West STP.
Available with a free Klarifi account
See the full treatment train at Caseyville Township West STP: structures, unit processes and planned upgrades, with exact unit counts.
Compliance snapshot (last 3 years)
- Total violations
- 0
- Effluent violations
- 0
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Capital improvement projects in O Fallon
O Fallon's capital improvement plan lists 21 water, sewer and wastewater line items worth $32M starting 2026–2029. The largest budgeted items are shown here.
All water and sewer capital projects in O Fallon →
| Project | Budget | Years |
|---|---|---|
| South Cherry Street Rehabilitation | $4,000,000 | 2027–2027 |
| Watermain Replacement Program | $3,200,000 | 2026–2030 |
| Hickory and Walnut Street Rehabilitation | $3,150,000 | 2027–2028 |
| South Trunk Main Replacement Phase 3 | $2,100,000 | 2027–2028 |
| North Trunk Main Replacement Phase 2 | $2,100,000 | 2029–2030 |
Full project details — scope, funding source, engineering consultant and the decision-makers behind each project — are available in Klarifi, along with similar wastewater capital projects in other cities.
Key contacts
1 verified contact for Caseyville Township West STP, with validated emails and direct phone numbers.
Unlock 1 verified contact
Names, validated emails and direct phone numbers for decision-makers at Caseyville Township West STP, plus the full compliance history and discharge data.
Nearby wastewater treatment plants in Illinois
O Fallon · 1 mi away
2.36 MGD
Swansea · 5 mi away
1.81 MGD
Belleville · 6 mi away
1.08 MGD
Collinsville · 6 mi away
11.53 MGD
O Fallon · 6 mi away
2.57 MGD
Belleville · 7 mi away
0.94 MGD
Lebanon · 9 mi away
0.58 MGD
Mascoutah · 11 mi away
1.04 MGD
Caseyville Township West STP: frequently asked questions
Sources and methodology
Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.
Data refreshed October 26, 2026; facility record last updated May 18, 2025.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Biosolids · Filter press · all terms