07-06-2021 WS - Laserfiche WebLink

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Past Assessments: The LWSMP, completed by Stantec — provides an overview and report of the infrastructure of the system; pipes, outfalls, catch basins, flow control devices, ponds, etc. It does not measure or assess the ponds, functionality, overall hydraulics of the system, and water quality throughout the system. In 1987 and 2012 assessments were done on Silver View Pond, both expressing concerns regarding vegetation with the 2012 assessment more specific to sedimentation levels. Barr Engineering conducted that assessment and opined a dredging need this mid -decade with an estimated cost of one to two million. However, it has been discovered that the assessment was done without the benefit of the original grading plan which may have a major impact on that assessment. The pond is very shallow with depths of 1' to 5' sans the very westernmost portion which was originally excavated to 10' to 14'. Constructed in 1982 as part of the housing and commercial development, a pre -sedimentation pond was constructed in 2004 and is less than half full. That accumulation is primarily the washout from the culvert failure resulting in us relocating part of the ditch from where it was, into the sedimentation pond! Other than these two assessments, there has not been any kind of comprehensive assessment of our "system" which does include ponds — both private and public, water quality, and with a lens on long term maintenance an optimum functionality of the system. That phrase — optimum functionality is sub -district unique. For example, Edgewood — which includes Silver View Pond would likely be defined by most as meaning the pond not turning green and the vegetation restored such that you can see the pond, wildlife flourishes, and the water quality is restored. For Arden, that phrase may mean conveying the water (that should be conveyed), away so it reduces the number of storm water complaints at or on various properties AND then our stormwater infrastructure which has failed and resulted in costly repairs due to water being backed up in the pipe would be less likely to fail saving us time and money on future maintenance and repairs. RFP Process: Stantec, Barr Engineering, and AE2S were all invited out to visit and tour the Arden, Greenfield, and Edgewood sub -districts along with visiting to discuss the project. Based on their input and our collective knowledge we would issue a RFP that would result in the assessment of the entire system, analyzed by Sub -District, and sub -district ponds for the purpose of developing a long term Capital and Maintenance Plan. Stantec has identified existing structures in the LSWMP (local surface water management plan such as outflows, skimmers, flow restrictors, etc.) that need attention or repair. However, no pond assessment (sedimentation or water quality analysis) has been done sans some work by Rice Creek Watershed but not specific to our storm water system.