9.2 Water, Wastewater, Stormwater, and Drainage Controls

Managing Water Before It Leaves the Site

Water is the fastest environmental pathway: it carries dissolved chemicals, suspended solids, oil, metals, heat, nutrients, biological material, and debris. The ASP candidate need not be a wastewater engineer, but must recognize that once a contaminant reaches a drain, ditch, sewer, sump, creek, or unprotected soil, the site faces an environmental problem, not a housekeeping defect.

Identify the Water Stream First

• Sanitary wastewater — restrooms and domestic uses, normally routed to a publicly owned treatment works (POTW).
• Process wastewater — washing, rinsing, cooling, plating, cutting, food processing, or lab work; often regulated under a discharge permit or pretreatment standard.
• Stormwater — precipitation runoff, regulated under the Clean Water Act NPDES program and typically managed through a Stormwater Pollution Prevention Plan (SWPPP).
• Noncontact cooling water — may be cleaner than contact wastewater but still needs control if it can pick up contamination.
• Contaminated firewater — spill- or fire-response water that became hazardous by contacting stored chemicals; pre-incident planning should account for its containment and recovery.

Stormwater deserves special attention because it begins clean and becomes regulated only after contact with exposed material: outdoor drums, open scrap bins, leaking dumpsters, dusty yards, salt piles, oily equipment, and uncovered waste. A dry-weather walkthrough can miss the pathway that appears during the first heavy rain after a long production run — the so-called first flush, when accumulated dust and residue wash off all at once and carry the highest pollutant load of the storm.

Drain Mapping and the SPCC Connection

Workers often assume every floor drain reaches a treatment plant. In reality, routing varies by building age, renovation, and temporary connections — a drain may lead to sanitary sewer, process treatment, storm sewer, an oil-water separator, a sump, a holding tank, or open discharge. Many ASP scenarios hinge on whether the candidate confirms where the drain leads before allowing washdown or spill cleanup. Facilities storing oil above the regulatory threshold (the EPA SPCC rule applies at an aggregate aboveground capacity over 1,320 gallons) maintain a Spill Prevention, Control, and Countermeasure plan that documents containment and drainage.

Prevention Beats Treatment

Keep materials under cover, close containers, maintain equipment, segregate incompatible streams, use dry cleanup when practical, and protect drains during high-risk work. When treatment is unavoidable, match it to the contaminant and the discharge limit: settling removes solids, oil-water separation removes free oil, neutralization adjusts pH, filtration removes particulate, and biological treatment addresses organics. Each solves a different problem.

Monitoring proves controls work: sampling, visual inspections, maintenance logs, discharge checks, and corrective actions. Treat a sudden color change, odor, foaming, sheen, fish-kill report, or clogged drain as a signal to investigate, not a nuisance to wash away.

Regulatory Framework in Plain Terms

The Clean Water Act governs discharges to "waters of the United States." A facility that discharges process wastewater to surface water needs an individual or general National Pollutant Discharge Elimination System (NPDES) permit with numeric effluent limits and a monitoring schedule. A facility that discharges to a municipal sewer instead falls under pretreatment standards — the POTW sets local limits to protect its biological treatment and to prevent pass-through or interference.

Industrial stormwater is typically covered by a Multi-Sector General Permit, which requires the SWPPP, routine visual inspections, and benchmark monitoring of indicator pollutants. You do not need to memorize numeric limits for the ASP, but you should recognize which permit world a given discharge lives in, because that determines who must be notified and what records prove compliance.

A Washdown Decision Walkthrough

A maintenance crew wants to pressure-wash a parts-cleaning area at the end of a shift. The ASP-defensible steps in order: (1) determine what residues are present — solvent, oil, metal fines; (2) map the floor drain to learn whether it goes to the sanitary sewer, an oil-water separator, or the storm sewer; (3) if it routes to storm, block the drain and capture the wash water; (4) decide whether dry cleanup (sweep, vacuum, wipe) can replace washing entirely; (5) if wet cleanup is necessary, collect the water for proper management; and (6) record the decision. Notice that no step relies on dilution or on hoping the volume is small.

For ASP items, choose the answer that protects the pathway: do not hose spilled powder toward a storm drain, do not blend unknown streams to dilute a problem, and do not assume rain is harmless after it contacts residue. The reliable sequence is stop the source, contain, identify the drainage route, notify the responsible role, characterize if needed, and document corrective action.