Appendix A Site Drawings and Details
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

Year Executed: 2010

4.2.6.8, 4.2.6.9

Trash, debris, organics, and sediment. 

Riverton Public Works Department, and Engineering & Stormwater Division staff

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.

1. 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. 
2. 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.
3. 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.
4. 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.
5. 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.

Evaluate the success and failure of retrofit projects. 

Flood Control Engineer, Public Works Director

Storm Drain Fee, General fund

Stormwater Design Standards and Regulations

Water Quality Basin Map
Retrofit Rank Report under development
Public Retrofit Projects
Public Project Retrofit Log
State Retrofit Program Guidance

2021-2022

The program is functioning but the program does not currently include a retrofit site ranking system and budgeted projects as expected by State USWAC retrofit guidance document.  Some City projects were designed without an site retrofit evaluation.  More City Department and Division support is necessary.  The Public Works Department and Stormwater Division have retrofitted two properties, see Retrofit Log.

Year Executed: 2010

4.2.1.5, 4.2.6.6, 4.2.6.6.1, 4.2.6.6.2, 4.2.6.6.3
Implement programs that require compliance with construction activities indicated by UTS00001; including but not limited to; Developoment review standards, templates, checklist and enforcement.

Sediment, fugitive dust, cementitious material, trash, non-stormwater liquids, and nutrients.

Developers, Contractors, Utility Companies, Right of Way Encroachment Officer, UPDES Staff, Flood Control Engineer

The Right of Way Encroachment Permit program involves a traditional permitting process using a permit application form as a document for creating a contractual relationship and establishing terms and conditions that are supported by ordinance.  The Right-of-Way Encroachment Program facilitates a safe project environment and public infrastructure restoration details and other needs.   As right of way encroachment work exposes drainage systems to construction pollution, the Right of Way Encroachment Program has been expanded to include requirements that facilitate containment of construction related impacts and pollution.  The program facilitates construction related submittals including best management practices (BMPs).   In addition, the program facilitates pre-construction meetings and communication where operational and structural BMPs are explained and reinforced.    The permitting process also facilitates obtaining a Land Disturbance Permit for longer term projects, projects warranting NOI regulation and more detailed SWPPPs.  The criteria for Land Disturbance permits are described by the Right of Way Encroachment Permit SOP.

Maintain contractor communication log for site exposures and operation concerns, the BMP direction provided and the response by the contractor.

Right-of-Way Encroachment Officer, Flood Control Engineer

Storm Drain Fee and General Fund

Conclusion: