MCM6 Regulation Summary
Minimum Control Measure 6 requires programs for adequate municipal operations and maintenance, including and not limited to SOPs, Long-Term Stormwater Management Plans, inspections.
Programs
6.1: Long-Term Stormwater Management Plan Riverton Facilities
6.2: Service Contract Operation and Maintenance
6.3: Sweeping
6.4: Drainage System Maintenance
6.5: Public Infrastructure Retrofit
6.6: Right of Way Encroachment Permit
6.1: Long-Term Stormwater Management Plan Riverton Facilities
Public Works Shop Site Plan
Public Works Site Plan and Details
Appendix B SOPs
Appendix C Weekly and High Priority Inspection Log 4150 W Log
Appendix B Site Evaluations
Monthly Visual and Semi-Annual Comprehensive inspections for all sites are incomplete for all sites and Annual Visual Observation of Storm Water Discharge inspections for priority sites are incomplete. The Monthly Visual Inspections that were completed and discussion with staff field operators indicate many City maintenance operations are following SOPs.
6.2: Service Contract Operation and Maintenance
6.3: Sweeping
403 tons of material was removed from roads which is equivalent to 40 ten-yard, truckloads of sediment, organics and trash from reaching canals, creeks and the Jordan Riverton; see Street Sweeping Annual Report. This program is successful not only for reducing pollutant loads to our waterways but also fulfilling roadway appearance expectations from the general public.
6.4: Drainage System Maintenance
Evaluate hydrovac and channel maintenance operations performance and draw conclusions.
Responsible Staff:
61 tons of material was removed from pipes which is equivalent to 5 ten wheel truck loads of pipe sludge, organics and trash from reaching canals, creeks and the Jordan Riverton; see Hydrovac Annual Report. This program is successful not only for reducing pollutant loads to our waterways but also reducing flood risk.
6.5: Public Infrastructure Retrofit
The UPDES regulation requires municipalities to retrofit existing public flood control infrastructure that adversely impacts water quality with systems that infiltrate, achieves evapotranspiration or harvest and reuse stormwater runoff. Permit reference UTS000001, 4.2.6.9.
Riverton City’s Retrofit program consist of a list of retrofit projects identified and described by Table 1 and Figure 1.
Table 1 Identifies retrofit projects by rank. This is a working Table and is updated with design descriptions and budgets as approved. The Table also shows water quality retrofits already completed.
Figure 1 Shows the Riverton City drainage basins and risk indicators warranting retrofits. The Figure also shows water quality retrofits already completed.
Figure 1 is divided into 4 drainage system types. Traditional Systems, Detention LID, Retention Systems and Retention LID. Figure 1 also includes water quality devices. Water quality devices(WQD) help trap pollution but most of these systems do not infiltrate, evapotranspire or reuse stormwater runoff as required by the UPDES Retrofit Requirement, however, WQD’s do improve water quality and comply with other UPDES requirements.
Figure 1 Riverton City Drainage System Description Summary.
- Traditional systems are concrete curb, inlets, pipe and detention systems with low flow type infrastructure. These systems efficiently carry runoff and all contaminates carried with it to water bodies. These systems also increase runoff volumes because smaller volumes of runoff are infiltrated into the ground.
- Detention LIDs are traditional concrete curb, inlets, and pipe systems but runoff and all urban pollution is discharged onto the detention ponds surfaces that spill, infiltrate and filtered through their vegetated or pervious xeriscape surfaces. Detention LIDs trap urban pollution but during high flow events pollution can be scoured and discharged downstream.
- Retention systems are concrete curb, inlets and pipes that drain directly into subsurface soils usually into subsurface open type structures or gravel pore space but do not use surface pervious landscaping or vegetation to help distribute infiltration and filter urban pollution on the surface and more effect above ground biology. Retention systems do a good job and preventing urban pollution from reaching surface water bodies but municipalities who do not require adequate pretreatment will increase the risk of contaminating subsurface water bodies.
- Retention LIDs drain runoff through pipes or over the surface to pervious xeriscape or vegetation landscaping resulting in a portion of the runoff infiltrating or to evapotranspire prior draining into the subsurface soils or offsite. Retention LID that distribute runoff evenly across the project site mimic the predevelopment hydrologic condition better than retention LIDs the direct all runoff to a single pocket pond in the low corner of the property. Well designed retention LIDs can be more effective for managing urban pollution by increasing infiltration biofilter rates. Retention LIDs also reduce runoff volumes better reducing flood and nuisance water risk by improving overall infiltration capacity.
- Water quality devices (WQD) are structure devices that separate urban pollution from runoff. WQD vary widely from cartridge filters, centrifugal and siphon type separate systems. Filter cartridges can be designed to filter to any level but are expensive. Siphon systems remove floating material and heavy sediments from runoff but are not effective at removing pollution that dissolves in water and more more susceptible to scour. Centrifugal types are usually more effective at preventing scour, however are also more expensive but neither centrifugal or siphon types will remove water soluble pollutants and both are still susceptible to high flow scour. WQD were required by City standards from 2003 and the vast majority are siphon types and only a handful are centrifugal types.
Ranking System
Traditional drainage systems are the most common drainage design of urbanizing communities but most adversely impact runoff quality. Traditional flood control systems are very efficient at carrying all contaminates in its path directly to water bodies that floats or can be scoured from the roadway and pavement surfaces. In other words, any urban pollutants like oil, detergents, fertilizers, pesticides and organics intentionally or unintentionally ending up on pavements will be picked up with runoff and dumped directly to our creeks, canals and the Jordan River. Organics, in fact, despite being natural have a significant negative impact on water bodies simply because of the enormous volumes that collect on roadways. Organic material decomposes and draws oxygen from the water, in addition, this excess organic material, heat and slow moving water are the primary ingredients of algal blooms we experience almost annually.
The e coli TMDL should also be considered with the retrofit program simply because the overall e coli TMDL reduction regulation. E coli has many sources including wild animals. The e coli contribution rank will focus on impacts by pet, farm and equestrian animals.
Riverton began to urbanize 1970’s and the traditional drainage system was the flood control development standard until 2020. Consequently, 90% of the City flood control system consist of varying levels of the tradition type systems that warrant retrofits as do most cities across the State. After 2002, as a result of UDPES regulations most traditional systems were design with water quality devices but only occasionally detention LID. UDOT had a good detention LID program which was included with the 12600 South Design Build Project.
Since most drainage basins are traditional types the retrofit ranking is pollution risk as a function of land use type and basin size but also flood control and cost metrics. Basins with more retention, detention LID and retention LID systems and basins effective WQD are ranked lower.
Retrofit Rank Report under development
Public Retrofit Projects
Public Project Retrofit Log
State Retrofit Program Guidance
6.6 Right of Way Encroachment Permit
Implement programs that require compliance with construction activities indicated by UTS00001; including but not limited to; Developoment review standards, templates, checklist and enforcement.
Right-of Way Encroachment Application
Right of Way Encroachment Program Performance Report