14.2 Good Housekeeping Part 1: Concrete Washout, Equipment Maintenance, Materials Management, and Secondary Containment

Source Control Philosophy: Good Housekeeping and Pollution Prevention (12.6)

Whereas erosion and sediment control BMPs manage displaced soil particles, Good Housekeeping and Pollution Prevention BMPs (CESSWI Review Manual Section 12.6 and EPA Construction General Permit [CGP] Part 2.3) prevent chemical, caustic, petroleum, nutrient, sanitary, and solid-waste pollutants from ever contacting rainwater or stormwater runoff. Once dissolved chemicals, emulsified oils, or high-pH washwaters mix with stormwater, conventional sediment traps, silt fences, and inlet barriers cannot remove them.

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1. Concrete Washout (12.6.1)

Chute, mixer drum, concrete pump-truck hopper, wheelbarrow, and hand-tool washout water—derived from Structural Portland Cement Concrete, masonry mortar, stucco, plaster, grout, or concrete saw-cutting slurry—is explicitly classified as a prohibited illicit non-stormwater discharge under EPA CGP Part 1.3 and Part 2.3.4.

Pollutant Hazard: Caustic $\text{pH } 11\text{–}13$ and Heavy Metals

When water contacts uncured Portland cement, hydration reactions leach dissolved calcium hydroxide ($\text{Ca(OH)}_2$) and alkaline potassium/sodium hydroxides into solution, driving the liquid to a highly caustic $\text{pH of } 11\text{ to }13$ (comparable to household bleach or oven cleaner), accompanied by dissolved hexavalent chromium ($\text{Cr}^{6+}$), trace heavy metals, and fine suspended limestone/silica solids. If discharged to a storm drain or stream, caustic concrete washout water chemically burns fish gills, causes acute mortality in amphibians and benthic macroinvertebrates, precipitates calcium carbonate crusts that cement streambed spawning gravels, and violates narrative and numeric water-quality standards (typically $\text{pH } 6.5\text{ to }8.5$ or $9.0$).

Siting and High-Visibility Signage

• Minimum $50\text{-Foot}$ Setback: Locate designated concrete washout facilities on flat, stable upland ground at least $50\text{ feet}$ away from storm drain inlets, open drainage ditches, curb gutters, wetlands, and surface waters.
• Convenient Access & Signage: Position the washout area near the stabilized construction exit or primary concrete staging zone so ready-mix truck drivers can wash their chutes immediately after pouring without tracking mud across the site. Install durable, high-visibility "Concrete Washout" signage visible from the haul road so delivery drivers never dump chute washings onto bare ground or into roadside ditches.

Mandatory Leak-Proof Containment Designs

Under EPA CGP Part 2.3.4 and Review Manual Section 12.6.1, concrete washout facilities must provide $100\%$ leak-proof containment of both solids and caustic liquids so high-pH leachate cannot seep into underlying soil or shallow groundwater. Unlined earthen pits are strictly prohibited in permeable soils or where leachate can migrate. Approved designs include:

1. Prefabricated Watertight Containers: Commercial watertight steel roll-off washout bins (with sealed tailgates), rigid heavy-duty polyethylene washout tubs, or portable framed vinyl bladder systems—often paired with an inclined steel or timber ramp to accommodate low-clearance concrete pump-truck hoppers.
2. Plastic-Lined Bermed or Excavated Pits: Below-grade excavated pits or above-grade hay-bale, sandbag, or earth-bermed enclosures (minimum $10\text{ ft} \times 10\text{ ft}$ interior footprint) lined continuously with a single sheet of heavy-duty minimum $10\text{-mil}$ polyethylene plastic sheeting ($10\text{ to }30\text{ mil}$, or double-layered $10\text{-mil}$ sheeting placed over a smooth sand bedding layer free of sharp stones or roots). The plastic liner must be completely free of tears, punctures, holes, or unsealed seams, anchored securely over the outer berm crest, and fronted by a stabilized gravel approach pad so heavy mixer trucks do not back their tires onto the plastic edge and rip the liner.
3. Saw-Cutting and Coring Slurry Control: Wet concrete saw-cutting, diamond coring, and surface grinding generate fine, caustic $\text{pH } 12$ slurry that flows rapidly down paved gutters. Crews must capture saw-cutting slurry continuously at the blade using an industrial wet-vacuum, block downstream curb gutters with temporary Impervious Gutter Berms/putty dams, and transfer collected slurry into the leak-proof concrete washout container.

Inspection and Maintenance Triggers

• Daily & Routine Checks: Inspect washout facilities daily during active concrete pours and during every scheduled SWPPP inspection to verify that drivers are using the facility and that the plastic liner or bin has zero tears, punctures, or perimeter leaks.
• $50\%$ to $75\%$ Capacity Cleanout Trigger: Pump out liquid and break up/remove hardened concrete solids (or swap out the roll-off bin) whenever the washout facility reaches $50\%$ to $75\%$ of its design capacity, always maintaining at least $4\text{ to }12\text{ inches}$ of vertical freeboard below the top rim.
• Pre-Storm Tarp Cover: Cover the concrete washout facility with a secured waterproof tarp prior to any forecasted rainstorm so rainfall cannot fill the containment pit and overflow caustic high-pH liquid onto the surrounding ground.

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2. Equipment Maintenance and Cleaning (12.6.3)

Construction machinery—bulldozers, excavators, scrapers, loaders, pavers, cranes, and portable diesel generators—carries large volumes of diesel fuel, crankcase motor oil, high-pressure hydraulic fluid, gear lubricants, and ethylene glycol antifreeze.

Siting, Drip Pans, and Daily Leak Checks

• Off-Site Preference & $50\text{-Foot}$ Setback: Perform major equipment overhauls at off-site commercial repair facilities whenever feasible. All routine on-site fueling, greasing, and maintenance must occur inside a designated, flat, impervious or plastic-lined maintenance area located at least $50\text{ feet}$ away from storm drain inlets, drainage ditches, wetlands, and surface waters.
• Dedicated Drip Pans & Daily Inspection: Place drip pans, catchment trays, or hydrophobic absorbent pads underneath all parked heavy equipment, hydraulic hose couplings, and fuel-transfer valves. Inspect machinery daily before startup for weeping hydraulic cylinders, cracked hoses, or oil drips, and tag leaking equipment out of service until repaired. Never top off fuel tanks to the point of overflowing when solar heating expands the fuel.

Dry Spill Cleanup Rule & Absolute Prohibition on Hosing or Outdoor Soaps (12.6.3): Minor fuel, oil, or hydraulic fluid drips and spills must be cleaned up immediately using dry hydrophobic absorbent pads, socks, pillows, or granular clay absorbents (kitty litter / floor dry), which are then swept up, bagged, and disposed of as regulated petroleum/hazardous waste. NEVER hose down a fuel or oil spill with water, and NEVER apply soaps, detergents, or emulsifying degreasers outdoors! Soaps and degreasers chemically emulsify petroleum hydrocarbons into microscopic droplets suspended throughout the water column, allowing oil to bypass oil-water separators and hydrophobic booms while discharging toxic surfactants and dissolved hydrocarbons straight into storm sewers. If outdoor equipment washing is performed on site, use high-pressure water without any soap, detergent, or solvent over a contained wash pad that drains to a closed-loop recycling unit or sediment trap.

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3. Materials Management (12.6.4)

Improperly stored construction materials exposed to rainfall or stormwater run-on can leach toxic metals, nutrients, extreme pH, and organic solvents.

• Pollutant-Generating Materials Inventory: The SWPPP must inventory all potential pollutant-generating materials stored on site, including bagged Portland cement, lime, mortar, and agricultural gypsum; granular or liquid N-P-K fertilizers; herbicides and pesticides; paints, stains, epoxies, curing compounds, and solvents; asphalt emulsions and form-release oils; and pressure-treated or creosote-treated lumber.
• Pallet Elevation, Weatherproof Cover & Berming: Store all water-reactive, leachable, or powdered dry bags and chemical containers elevated off the ground on wooden pallets and under weatherproof cover—inside locked weatherproof storage trailers/Conex containers, beneath permanent roofed sheds, or covered with tightly secured waterproof tarps—surrounded by a perimeter berm so stormwater run-on cannot contact the materials. Keep containers closed with tight lids when not in active use, and segregate incompatible chemicals (e.g., oxidizers separated from flammables; acids separated from bases).
• 16-Section GHS Safety Data Sheets (SDS) & Spill Kits: Maintain a complete, accessible binder of 16-section Globally Harmonized System (GHS) Safety Data Sheets (SDS) for every chemical product on site, and station fully stocked spill response kits at the material storage yard and fueling station.

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4. Secondary Containment (12.6.6)

Secondary containment provides an outer, impervious barrier around bulk liquid chemical totes (IBCs), $55\text{-gallon}$ drums, and aboveground fuel storage tanks (ASTs) so that if the primary tank wall, sight glass, or dispensing valve ruptures, $100\%$ of the spilled liquid is captured before reaching soil or stormwater.

SPCC Regulatory Threshold and the $110\%$ Volumetric Sizing Rule

• 40 CFR Part 112 SPCC Threshold: Under the federal Oil Pollution Prevention regulation (40 CFR Part 112 — Spill Prevention, Control, and Countermeasure [SPCC] rule), a formal SPCC Plan with compliant secondary containment is legally mandatory whenever a site's aggregate aboveground oil storage capacity exceeds $1,320\text{ gallons}$ (counting only containers with a shell capacity of $55\text{ gallons}$ or greater) or buried underground storage exceeds $42,000\text{ gallons}$.
• Mandatory $110\%$ Volumetric Sizing Rule: Every secondary containment dike, concrete/steel basin, lined earthen berm, or modular polyethylene drum spill pallet must be constructed of impervious material (free of unsealed cracks, seams, or rodent burrows) and sized to hold at least $110\%$ of the volume of the single largest tank or container located inside the containment footprint (or $10\%$ of the aggregate volume of all containers within the dike, whichever is greater). This provides $100\%$ containment of a catastrophic rupture of the largest tank plus a $10\%$ volumetric freeboard allowance for precipitation.

Secondary Containment Drain Valve Lockout & Dewatering Protocol (12.6.6): If an outdoor secondary containment berm or dike is equipped with a gravity stormwater drain pipe and valve, the drain valve must remain LOCKED in the CLOSED position at all times. Accumulated rainwater inside the containment basin may be discharged to the ground only after a qualified inspector:

1. Visually inspects the impounded water to verify zero visible petroleum sheen, oil film, floating droplets, chemical discoloration, or hydrocarbon odor;
2. Unlocks and opens the valve under direct supervision to drain the clean rainwater slowly across a stabilized, vegetated upland area;
3. Immediately closes and re-locks the drain valve upon completion; and
4. Records the date, inspector name, visual sheen verification, and discharge event in the SWPPP / SPCC containment drainage log. If any petroleum sheen or chemical contamination is detected, the valve must remain locked shut and the contaminated liquid must be skimmed with hydrophobic oil-absorbent pads/booms or pumped out by a licensed hazardous-waste vacuum truck.

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Summary of Good Housekeeping Part 1 BMP Standards

SPCC sizing and chemical-treatment qualification

For the detailed method and approval qualifications, review the related CESSWI explanation.