CHAPTER 6 - BARNEY'S CREEK CONSIDERATIONS
While the City's storm drainage master plan was in progress, a separate study was being completed by Salt Lake County (County) Flood Control District that has been titled "Southwest Canal and Creeks Study" (SWCCS) (see Appendix E). As part of that study, the capacity and condition of many of the County Flood Control facilities in the southwest portion of the County were evaluated. A memorandum summarizing the results from the SWCCS analysis specific to Barney's Creek was provided to the City by the County.
The SWCCS included the following statement: "It is recommended that West Jordan City representatives review the Technical Memorandum in (SWCCS) Appendix F in Section 3 of this report and select the recommended alternative to manage storm water runoff from future development in the Barney's Creek drainage basin. The recommended alternative should be reviewed with Salt Lake County. This process should be completed while West Jordan is updating their storm drain master plan." This Chapter is in response to this recommendation and will detail the plan of action that West Jordan City would like to incorporate to manage runoff within their City.
SWCCS AND WEST JORDAN STORM DRAIN MASTER PLAN COMPARISON
SWCCS SUMMARY
The SWCCS provided the following recommendations for managing future stormwater runoff to Barney's Creek.
∙ Limiting the peak discharge from Future Development -The final recommended discharge rate may be the pre-development discharge rate of 0.02 cfs/ac, or a different rate selected by the City as part of their more detailed master planning process. The proposed discharge rate should be analyzed in the comprehensive model of Barneys Creek and the West Jordan Storm Drain System.
∙ Additional Regional Detention Facilities - The 2003 and 2012 storm drain master plans recommended large regional detention facilities to limit the peak discharge in Barneys Creek. As part of their storm drain master planning process, West Jordan City should analyze different areas where regional detention facilities could be constructed to limit the peak discharge in Barneys Creek. Alternative detention facility improvements should be analyzed in the comprehensive model of Barney Creek and should be incorporated into the West Jordan Storm Drain Master Plan.
∙ Improving Culverts on Barneys Creek - At least three culverts need to be improved or replaced to safely convey the estimated 100-year peak discharge associated with existing development conditions. There may be more improvements to the West Jordan Storm Drain System, depending on proposed regional facilities or the required peak discharge rate for future development.
The SWCCS notes that previous West Jordan Storm Drainage Master Plans had identified several large regional detention facilities that would limit runoff from the mountain watershed areas and development west of Bacchus Highway (SR-111) that have not yet been constructed. The SWCCS indicates their analysis did not include these facilities because they have not been constructed yet. This Storm Drainage Master Plan reaffirms West Jordan's intent to construct those facilities as development occurs.
WEST JORDAN STORM DRAIN MASTER PLAN SUMMARY
West Jordan City plans to implement the following actions to manage future stormwater runoff to Barney's Creek.
∙ Limiting peak discharge from future development to 0.1 cfs/acre for all development west of Mountain View Corridor.
∙ Constructing regional detention facilities identified in the Master Plan to limit mountain watershed flows and development west of SR-111.
∙ Improve culverts along Barney's Creek that master plan has identified as deficient.
Figure 6-1 provides a comparison between the results of the SWCCS and the current West Jordan Storm Drainage Master Plan along Barney's Creek. Key differences to note as these are compared is that the SWCCS did not account for the regional detention facilities being constructed whereas the West Jordan Master Plan results do include those facilities. Additionally, there are differences in modeling software, design storms, level of detail, and other assumptions that can yield different results. Hydrologic modeling is a science that involves uncertainty and engineering judgment, these often result in differences in model results.
