Why a 2026 NOV is arriving at more Huntington-area bulk plants than at any point in the last decade
A Notice of Violation citing a hexane-extractable material (HEM) exceedance, a 30-day cure window, and a footnote that escalates the event to Significant Noncompliance (SNC) if the next two reports miss the mark — that letter is landing on more petroleum bulk plants within 30 miles of Huntington, IN in 2026 than in any prior year of the last decade. Three pressures are converging: aging POTW infrastructure struggling with hydraulic and biosolids capacity, more aggressive EPA pretreatment audits under the 2024–2026 National Pretreatment Program review cycle, and intensifying water-reuse demand in the Wabash basin (per the ACS ES&T Engineering 2021 review on U.S. industrial water scarcity and reuse). Under 40 CFR Part 403, any discharger that meets the Industrial User criteria — generally facilities that discharge process wastewater to a POTW, or contribute ≥25,000 gpd of non-domestic waste — is an IU. Most petroleum bulk plants around Huntington fall under noncategorical SIU status, while dedicated refinery or fuel-blending operations may be categorical. Once the POTW issues a permit, the operator owns the daily free-oil inspection log, the monthly HEM composite result, and the 30–60 day cure window that sits between a late report and a SNC finding. SNC carries administrative orders, surcharges, mandated zero-discharge status, or permit termination — so the equipment decisions made this quarter determine whether the terminal operates normally or spends 2027 in enforcement limbo. A related compliance framing for a similar noncategorical-SIU population is detailed in the Cincinnati petroleum pretreatment guide.
The three-tier compliance ladder every Huntington-area terminal must clear
The citation chain a Huntington-area terminal engineer can hand to an Indiana Department of Environmental Management (IDEM) inspector runs Clean Water Act of 1972 (33 U.S.C. § 1251 et seq.) → EPA General Pretreatment Regulations at 40 CFR Part 403 → Indiana 327 IAC 5 Industrial Wastewater Pretreatment Programs (NPDES), incorporated by reference in Huntington Ord. 16-C-20 (2020) → City of Huntington § 51.032 (Ord. 2-C-26, passed 3-10-26) local limits and prohibited discharges. The analytical surrogate matters as much as the number: HEM is the federally used proxy for fats, oils, and grease in U.S. pretreatment — defined in 40 CFR § 401.16 and Method 1664A — and is what most Huntington-area bulk plant permits cite as "O&G." Local limits at the Huntington POTW are derived using EPA's Maximum Allowable Headworks Loading (MAHL) method, which converts four regulatory inputs into a per-user allocation: (1) NPDES permit limits on the receiving POTW, (2) state water quality standards for the receiving stream, (3) Part 503 biosolids disposal criteria, and (4) local worker/ecosystem protection factors such as NIOSH thresholds (per the 2020 St. Joseph, MO TBLL evaluation by Black & Veatch, final report adopted 2020-12). The POTW then converts MAHL into a Maximum Allowable Industrial Loading (MAIL) for each SIU, allocates mass against flow, and prints the result as daily-maximum and monthly-average numbers on the discharge permit. Where state and federal standards conflict, the more stringent applies (Huntington § 51.032(C)) — a clause that keeps a terminal from arguing its way out of a parameter by pointing to a weaker federal floor.
| Tier | Authority | Instrument | What it controls |
|---|---|---|---|
| 1 — Federal | EPA / 33 U.S.C. § 1251 et seq. | 40 CFR Part 403 (general pretreatment); 40 CFR § 401.16 (HEM definition) | Pass-through and interference prohibitions; categorical standards (Parts 405–471) |
| 2 — State | Indiana DEM / 327 IAC 5 | Industrial Wastewater Pretreatment Programs (NPDES), incorporated by Huntington Ord. 16-C-20 | State-side enforcement, IU permitting, SIU definitions; more stringent where state and federal overlap |
| 3 — Local | City of Huntington POTW | § 51.032 (Ord. 2-C-26, 2026) — local limits, specific prohibitions, surcharge triggers | Numerical ceilings, prohibited discharge clauses, FOG cap, mercury ND trigger, § 51.103 surcharges |
What the City of Huntington actually puts on the discharge permit
Huntington § 51.032(A)(2)(r) sets the headline number for any petroleum SIU: no user shall discharge wastewater containing more than 100 mg/L total fats, oil, grease, or wax, whether emulsified or not. That ceiling sits below the 100–200 mg/L HEM range most U.S. POTWs use, so the DAF target residual must be set at ~50 mg/L with 20–30% margin to absorb slug loads. The specific-prohibitions list under § 51.032(A)(2) also locks down the physical envelope: closed-cup flashpoint must be ≥140°F (60°C) per 40 CFR 261.21, pH must fall between 5.0 and 12.0, solids may not exceed ½ inch in any dimension, and wastewater temperature must stay ≤150°F (65°C) waste-side and ≤104°F (40°C) at the POTW headworks. Local numerical limits for metals are tighter than the federal floor: ammonia 97 mg/L, total chromium 3.73 mg/L, molybdenum 1.9 mg/L, selenium 0.263 mg/L, zinc 1.72 mg/L, and mercury ND with quantification at 0.2 µg/L (Method 245.1) or 0.5 ng/L (Method 1631) — any detection at or above the quantification level is an exceedance. Surcharge triggers under § 51.103 activate at 210 mg/L BOD or 230 mg/L TSS; holding both below the FOG ceiling avoids stacked surcharges on the same monthly bill. Most consequentially, § 51.032(A)(2)(v) prohibits chemical or biological agents that "dissolve, liquefy, suspend, disperse, emulsify, entrain, or otherwise directly or indirectly enable fats, grease, wax, or other similar material to flow through the wastewater collection system" — a structural block on dispersant chemistry that forces the design toward DAF with coagulant or demulsifier dosing rather than toward a chemical-dispersal shortcut.
| Parameter | Huntington § 51.032 limit | Method / note |
|---|---|---|
| FOG / HEM (total) | 100 mg/L (§ 51.032(A)(2)(r)) | EPA Method 1664A (n-hexane); design DAF to ~50 mg/L with margin |
| pH | 5.0–12.0 (§ 51.032(A)(2)(b)) | Continuous at discharge point |
| Flashpoint | ≥140°F / 60°C (§ 51.032(A)(2)(a)) | 40 CFR 261.21 closed-cup |
| Temperature | ≤150°F waste; ≤104°F at headworks (§ 51.032(A)(2)(e)) | — |
| Ammonia | 97 mg/L (§ 51.032(D)(1)) | — |
| Chromium, total | 3.73 mg/L (§ 51.032(D)(1)) | — |
| Molybdenum | 1.9 mg/L (§ 51.032(D)(1)) | — |
| Selenium | 0.263 mg/L (§ 51.032(D)(1)) | — |
| Zinc | 1.72 mg/L (§ 51.032(D)(1)) | — |
| Mercury | ND; QL 0.2 µg/L (Method 245.1) or 0.5 ng/L (Method 1631) | Any detection ≥ QL is an exceedance |
| BOD surcharge trigger | 210 mg/L (§ 51.103) | High-strength surcharge applies above ceiling |
| TSS surcharge trigger | 230 mg/L (§ 51.103) | High-strength surcharge applies above ceiling |
| Emulsifier / dispersant | Prohibited (§ 51.032(A)(2)(v)) | No agents that disperse, emulsify, or entrain FOG |
The four-stage pretreatment train and why skipping a stage fails in the field
A bulk plant pretreatment train has four stages, and the order is non-negotiable: source segregation first, primary oil/water separation second, DAF polishing third, biological or adsorption polish fourth. Stage 1 keeps hydrocarbon-contaminated streams out of clean stormwater — segregated laterals on product-handling pads, covered dump valves, and dedicated oil/water sewering on truck-loading islands reduce train influent volume 40–70% in field retrofits (Zhongsheng field data, 2025–2026), converting most of the remaining flow from "design problem" to "design choice." Stage 2 is the free-oil primary: an API gravity separator, a CPI corrugated plate interceptor, or a plate/multimedia coalescer handles droplets ≥60–150 µm, with residence time ≥30 minutes at peak flow and CPI plate spacing 1–2 inches at ~45° corrugation. Stage 3 is DAF polishing, where a ZSQ series dissolved air flotation (DAF) system floats oil droplets down to 10–25 µm using micro-bubbles generated at 60–90 psig, with air-to-solids ratio (ASR) ~0.02–0.05 held with a 20–30% safety margin and surface hydraulic loading 2–5 gpm/ft². Stage 4 — biological (MBBR or MBR) or adsorption (GAC) — is engaged only when ammonia, sulfide, or dissolved hydrocarbon limits demand it, and a HydropureWater MBR integrated wastewater treatment train with 0.1 µm PVDF flat-sheet modules is the reference path for the polish step. The chemistry ahead of the DAF is dosed by a PLC-controlled automatic chemical dosing system, set to pH 6.5–7.5 with coagulant or demulsifier at 50–200 mg/L. Field finding: a DAF alone without a CPI/API primary fails under slug loads from coalescer dumps, because free oil blankets the bubble surface and crashes the air-to-solids ratio (Zhongsheng field data, 2026). Skipping Stage 2 to save capex is the single most common cause of DAF underperformance in the field.
Choosing the primary separator: API, CPI, coalescer, or DAF-as-primary
The primary separator is the highest-leverage equipment decision in the entire train; the four technologies sit in different performance bands and are not interchangeable. API gravity separators are high-throughput and slug-tolerant but footprint-heavy, and they cannot break emulsions. CPIs are compact with vertical configurations, but they rarely meet <100 mg/L on emulsified wash-rack waste and are sensitive to plate fouling. Coalescers (plate or multimedia) deliver polishing-grade residual at 5–10 gpm/ft², but media replacement every 1–3 years drives higher O&M. A DAF as a primary is only viable where free oil is pre-strained; it is slug-sensitive without an upstream primary and requires the air saturation system. The robust path for a Huntington-area terminal on emulsified wash-rack and loading-arm flow is CPI or API as primary, then a ZSQ series dissolved air flotation (DAF) system as the emulsified-oil polisher, sized with a 20–30% safety margin on hydraulic and air-to-solids loading. For a head-to-head DAF vs clarifier framing on a similar waste profile, the DAF vs clarifier worked example applies the same hydraulic-loading math to a comparable waste stream.
| Technology | Droplet-size band | Hydraulic loading | Best-fit terminal type | Key limitation |
|---|---|---|---|---|
| API gravity separator | Free oil ≥150 µm | Vendor-specific; large footprint | High-throughput marine terminal, large flow swings | Cannot break emulsions; sensitive to turbulence |
| CPI (corrugated plate interceptor) | Free oil ≥60 µm | Vendor-specific; vertical configs available | Small-to-mid terminal with steady flow; retrofit into existing vault | Rarely meets <100 mg/L on emulsified waste; plate fouling |
| Coalescer (plate or multimedia) | ~20–60 µm | 5–10 gpm/ft² (vendor-specific) | Polishing stage or low-flow sites with strict <50 mg/L needs | Higher O&M; media replacement 1–3 yr |
| DAF as primary | 10–25 µm (emulsified/colloidal) | 2–5 gpm/ft² surface; ASR ~0.02–0.05 | Truck-loading rack with emulsified oils; primary only where free oil is pre-strained | Slug-sensitive without upstream primary; needs air saturation system |
A worked DAF sizing example for a 50–200 gpm Huntington-area bulk plant
Three numbers drive a defensible DAF design: peak instantaneous flow (gpm, not the daily average — slug loads during a coalescer dump or a tank drop can spike 3–5× the daily mean), daily O&G load (lb/day from tank turnover, wash-rack volume, and drip rates), and target residual HEM (~50 mg/L to give 20–30% margin under Huntington's 100 mg/L ceiling). For a representative 50–200 gpm Huntington-area bulk plant, the sizing window falls inside the 13-model ZSQ range of 4–300 m³/h (≈18–1,320 gpm), so a model selection with a 20–30% safety margin on hydraulic loading and ASR typically lands a mid-frame ZSQ unit without oversizing capex. DAF chemistry is the only compliant path given § 51.032(A)(2)(v): pH 6.5–7.5 ahead of the DAF and a coagulant or demulsifier dose of 50–200 mg/L via a PLC-controlled HydropureWater automatic chemical dosing system, dosed to break the emulsion rather than to disperse it. Surface hydraulic loading of 2–5 gpm/ft² and ASR ~0.02–0.05 with a 20–30% safety margin set the footprint and air-supply sizing; undersizing either is the most common cause of carryover in field retrofits. For sites pushing toward water-reuse (<20 mg/L HEM), the polish step swings from biological (MBR) to adsorption (GAC), and the DF series PVDF flat sheet MBR module at 0.1 µm nominal pore size is the reference polish path. For fouling control on that MBR polish, the membrane fouling prevention strategies post walks through the operating setpoints that keep trans-membrane pressure inside the vendor envelope.
| Design input | Value or range | Source / note |
|---|---|---|
| Peak instantaneous flow | 50–200 gpm typical; slug spikes 3–5× daily mean | Daily average is not a design flow |
| Target residual HEM | ~50 mg/L (20–30% below the 100 mg/L Huntington ceiling) | Huntington § 51.032(A)(2)(r) |
| pH ahead of DAF | 6.5–7.5 | Optimizes coagulant / demulsifier performance |
| Coagulant or demulsifier dose | 50–200 mg/L | Compliant with § 51.032(A)(2)(v) emulsifier ban |
| ASR (mass air / mass solids+oil) | 0.02–0.05 with 20–30% safety margin | Zhongsheng field data, 2026 |
| Surface hydraulic loading | 2–5 gpm/ft² | Oilfield-service reference range |
| ZSQ model envelope | 4–300 m³/h (≈18–1,320 gpm) | 13-model ZSQ range brackets the typical bulk plant |
| Water-reuse polish (where required) | MBR 0.1 µm PVDF flat-sheet or GAC | For <20 mg/L HEM targets |
Self-monitoring, reporting, and the BMP checklist that keeps a terminal out of SNC
The minimum self-monitoring cadence most Huntington POTW permits expect in 2026: daily visual free-oil inspection at the outlet weir (logged, dated, initialed), weekly TSS grab, monthly HEM composite per EPA Method 1664A (24-hour flow-proportional where the permit specifies), and a 24-hour flow-proportional composite for BTEX/TPH where the local limit is non-zero. Sampling taps must be accessible, the flow meter calibrated annually, and chain-of-custody defensible — most SNC findings at petroleum bulk plants originate from sampling-procedure deficiencies, not from the underlying treatment performance (Zhongton field data, 2025–2026). Under EPA's National Pretreatment Program, SNC is triggered by any of the following: a numerical limit exceeded by ≥1.5× on any single day, a numerical limit exceeded for >5% of measurement days in a 6-month period, or a required report filed more than 30 days past its due date. The BMP checklist a Huntington pretreatment coordinator will look for during a 2026 audit: spill containment around all aboveground storage tanks, drip pans under truck loading arms, covered and locked dump valves on coalescers, segregated sewer laterals that keep product-handling pads out of the clean stormwater system, visible tagging of all sample points, and a written SPCC plan (40 CFR Part 112) tied to the sewer map. Running this list typically eliminates ~half of common audit findings, and the SPCC-to-sewer-map linkage is the cheapest single item to fix.
The consequence matrix and what to do this quarter
The consequence matrix is linear and avoidable: one late monthly report triggers a Notice of Violation; two within twelve months escalate to Significant Noncompliance; SNC triggers a Show Cause hearing and potential permit action including administrative orders, surcharges, mandated zero-discharge status, or termination. For a Huntington-area terminal engineer, the ordered 2026 action list is: (1) confirm § 51.032 parameters on the active permit against the Ord. 2-C-26 (2026) text, (2) audit the existing train against the 100 mg/L HEM target with 20–30% margin, (3) evaluate the DAF chemistry path under the § 51.032(A)(2)(v) emulsifier prohibition — a ZSQ series dissolved air flotation (DAF) system with a HydropureWater automatic chemical dosing system is the reference equipment package for that path, (4) commission Method 1664A monthly sampling with documented chain-of-custody, and (5) pre-build the EPA National Pretreatment Program audit checklist file. For a terminal already in violation, the documented emergency playbook is fast-track DAF rental plus chemistry rebalancing to halt the SNC trigger, then a permanent rebuild sized to the worked example above.
Frequently Asked Questions
What is the FOG limit for a petroleum bulk plant discharging to the Huntington POTW in 2026?
100 mg/L total fats, oil, grease, or wax, whether emulsified or not, per Huntington § 51.032(A)(2)(r) (Ord. 2-C-26, passed 3-10-26). To stay defensible under slug loads, design the DAF polish to ~50 mg/L with a 20–30% margin, measured as HEM via EPA Method 1664A (n-hexane).
Does the City of Huntington ban dispersant chemistry for oil and grease?
Yes. § 51.032(A)(2)(v) prohibits chemical or biological agents that "dissolve, liquefy, suspend, disperse, emulsify, entrain, or otherwise directly or indirectly enable fats, grease, wax, or other similar material to flow through the wastewater collection system." The compliant path is DAF with coagulant or demulsifier dosing, not dispersant chemistry.
Can a DAF system alone meet a 100 mg/L HEM limit at a bulk plant?
Usually no. Free oil from coalescer dumps and tank drops blankets the DAF micro-bubbles and crashes the air-to-solids ratio, so a DAF alone fails under slug loads (Zhongsheng field data, 2026). A CPI or API primary stage ahead of the DAF is standard practice for a Huntington-area terminal.
What triggers Significant Noncompliance (SNC) under 40 CFR Part 403?
Any of the following: a numerical limit exceeded by ≥1.5× on any single day, a numerical limit exceeded for more than 5% of measurement days in a 6-month period, or a required report filed more than 30 days past its due date. An SNC can lead to enforcement action, surcharges, mandated zero-discharge status, or permit termination.
How is the HEM parameter measured and reported under EPA Method 1664A?
Method 1664A uses n-hexane extraction and is reported as Hexane Extractable Material (HEM). HEM is the federally used surrogate for fats, oils, and grease under 40 CFR § 401.16 and is the parameter most U.S. POTW permits — including Huntington § 51.032 — cite as "O&G."
