Regulations
Larimer County SWPPP Checklist: Concrete Washout & LCUASS Compliance
Larimer County
Jurisdiction: Larimer County (unincorporated MS4 areas, Fort Collins, and Loveland)
Permit / authority: Governing permits: Larimer County Land Disturbance Permit (LDP) / Larimer County Urban Area Street Standards (LCUASS)
Larimer County overhauled its stormwater program in 2023, implementing a strict Land Disturbance Permit (LDP) system for its MS4 boundary. Construction within this jurisdiction, heavily influenced by the shared Larimer County Urban Area Street Standards (LCUASS), requires precise concrete washout containment.
1. The Daily Maintenance & Signage Mandate
The Rule: The Erosion and Sediment Control Plan (ESCP) must describe and display on maps all potential sources of pollutants and appropriate stormwater control measures (SCMs). The Larimer Nuance: Larimer County Stormwater guidelines explicitly dictate that a concrete washout area must be designated with visible signage. Crucially, the county demands that this washout area must be checked and maintained daily to ensure compliance. Relying solely on the standard 14-day MS4 routine inspection cycle is insufficient in Larimer County and will result in a violation.
2. LCUASS 50-Foot Buffer & Contaminant Strictness
The Rule: Discarded building materials, concrete truck washout, and chemicals must be contained and disposed of properly. The Larimer Nuance: Under the shared LCUASS (adopted by Larimer County, City of Loveland, and City of Fort Collins), it is unlawful to allow the discharge of any concrete washout water. Standard Drawing Note 14 strictly mandates that the containment area must be constructed to hold the washout material and must be located at least fifty (50) feet away from any waterway during construction.
3. MHFD SCM Design Integration
The Rule: Control measures must function as designed to prevent pollutants from discharging to receiving waters and the storm drainage system. The Larimer Nuance: Larimer County's Chapter 16 Construction Stormwater Management manual specifically encourages applicants to follow the Construction BMPs chapter of the Mile High Flood District (MHFD) Manual in the design and implementation of construction SCMs. Washout setups that deviate from MHFD structural specifications (such as unlined dirt pits or lacking appropriate vehicle tracking control) face a high probability of ESCP rejection.
4. The "Unlawful Discharge" City Ordinance Cross-Over
The Rule: Routine site inspections are conducted by the permittee to ensure SCMs like concrete washout areas function correctly. The Larimer Nuance: Because Larimer County operates closely with Loveland and Fort Collins, county sites are often scrutinized under overlapping city ordinances. LCUASS explicitly notes that City Ordinance and Colorado Discharge Permit System (CDPS) requirements make it unlawful to discharge or allow the discharge of any pollutant (explicitly naming concrete truck washout). A leaking washout pan or pit is treated as a severe ordinance violation rather than a simple administrative BMP failure.
