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HomeMy WebLinkAbout007_Storm Water Maintenance PlanJOB NO. B21-099 MONTANA | WASHINGTON | IDAHO | NORTH DAKOTA | PENNSYLVANIA MAY 2022 406.586.0277 tdhengineering.com 234 East Babcock Street Suite 3 Bozeman, MT 59715 CLIENT ENGINEER Lake Flato Architects 311 Third Street San Antonio, TX 78205 TD&H Engineering 234 East Babcock Street, Suite 3 Bozeman, MT 59715 Engineer: Ahren Hastings, PE ON-SITE STORM WATER MAINTENANCE PLAN WALLACE WORKS BOZEMAN, MONTANA WALLACE WORKS Storm Water Maintenance Plan B21-099 1 WALLACE WORKS STORM WATER MAINTENANCE PLAN PURPOSE AND INTRODUCTION This maintenance plan identifies the recommended maintenance procedures necessary for the proper function of the on-site storm water management system proposed at the Nest Development project in Bozeman, Montana. For the purpose of this plan, the on-site storm water management system includes stormwater conveyance paths and pipes within the property; the subsurface retention chambers and inlets/manholes south and east of the parking structure; floor drain within the southeast corner of the parking garage; and the existing PVC stormdrains in East Tamarack Street and North Wallace Avenue to the north and east of the property. The maintenance responsibility for the on-site stormwater management system belongs to the landowner. The landowner may delegate routine inspection and maintenance responsibilities to the on-site facility operations management team or may hire a qualified professional entity or individual to perform certain monitoring and maintenance tasks as necessary. A log shall be kept for all required inspections and maintenance. These logs shall be made available to the City of Bozeman Public Works Department for review as requested. A sample maintenance log is included in the attached Appendix. STORM WATER MANAGEMENT SYSTEM The on-site storm water management system includes curb and gutter, curb inlets, area inlets, drainage chases, roof drain piping, and subsurface infiltration galleries. These various components of storm water management infrastructure are designed to collect, convey, clean, detain, and/or infiltrate storm water runoff that is generated on the property before it leaves the site or enters local waterways. Storm water systems require proper maintenance to prevent sediment clogging, overgrown vegetation, erosion of detention ponds, obstruction of inlets, pipes, and structures, and prolonged standing water. Such issues may result in downstream pollution, unpleasant odors, unsightly areas, nuisance insects, or algae blooms, and must be mitigated. Scheduled inspections, times of inspections, locations inspected, maintenance completed, corrective actions taken, and any modifications or reconstruction performed shall be documented in the maintenance logs to be readily available upon request. Disposal of accumulated sediment must be in accordance with all applicable local, state and federal regulations. Wetlands are not anticipated to be encountered during maintenance activities for the on-site subsurface infiltration facilities. However, maintenance of off-site locations where outlet pipes or overflows discharge to protected water bodies within wetland areas may require wetland or stream bank permitting. If unsure of the regulatory status of wetland features observed at the site, consult the local authorities prior to undertaking any activities that may cause disturbance. WALLACE WORKS Storm Water Maintenance Plan B21-099 2 STORM WATER MAINTENANCE PROCEDURES The following maintenance procedures are intended to prolong the life of installed system components and ensure their continued functionality: General Storm Water System Maintenance – 1. Parking lot areas, curbs & gutters, drainage chases, and area drains should be cleared of leaves and other debris once after primary leaf drop in the fall and once after snow melt in early spring at a minimum. This will minimize the potential for debris to enter the system which could lead to premature clogging of structures, reduced storage capacity, and/or blockage of inlets. 2. Inspect the storm drain inlets, overflow structures, and cleanouts, for sediment build-up or clogging and flush/clear as needed. Inspect for snow/ice buildup at least once weekly during winter months and clear the inlet as needed. Do not pile snow over inlets. 3. Snow storage should be performed in designated areas during winter months and should not be allowed to be piled in front of or over inlets. Piled snow around or over the inlets could block early snowmelt run-off from entering the system, possibly causing overflows and icy conditions. 4. Sanding of the parking lots and drive aisles should be done sparingly or avoided completely. Sand or other sediment on the parking lot will likely be washed into stormwater system components which can lead to buildup and reduced capacity or blockages over time. Sub-surface Infiltration Gallery (StormTech system) Maintenance – The subsurface infiltration systems are designed with isolator rows that capture the “first flush” of pollutants from runoff events. The isolator rows are equipped with inspection ports and direct manhole access for maintenance. The isolator row should be inspected for sediment buildup once every 6-months during the first year of operation, and once a year after that. Use the general preventative measures described above to help reduce sediment build up and clogging. Clean out sediment buildup as necessary following the attached manufacturer recommended procedures. APPENDIX Sample Maintenance & Inspection Log StormTech Isolator Row O&M Manual Storm Water Facilities Inspection and Maintenance Log Facility Name Begin Date End Date Date Location Facility Description Inspected by: Cause for Inspection Exceptions Noted Comments and Actions Taken Instructions: Record all inspections and maintenance for all storm water facilities on this form. Use additional log sheets and/or attach extended comments or documentation as necessary. Save all completed logs in one place and have them readily available for the City of Bozeman’s review upon request.  Location — Specify the exact location of the facility either by its name, facility ID or physical location.  Inspected by — Note all inspections and maintenance on this form, including the required independent annual inspection.  Cause for inspection — Note if the inspection is routine, pre-rainy-season, post-storm, annual, or in response to a noted problem or complaint.  Exceptions noted — Note any condition that requires correction or indicates a need for maintenance.  Comments and actions taken — Describe any maintenance performed and need for follow-up. FIGURE 1FIGURE 1 FIGURE 6 An company 2 THE MOST ADVANCED NAME IN WATER MANAGEMENT SOLUTIONS TM ECCENTRICHEADER MANHOLEWITHOVERFLOWWEIR STORMTECHISOLATOR ROW OPTIONAL PRE-TREATMENT OPTIONAL ACCESS STORMTECH CHAMBERS  )( StormTech Maintenance Log Project Name: Location: Stadia Rod Readings Date Fixed point to chamber bottom (1) Fixed point to top of sediment (2) Sediment Depth (1) - (2)Observations / Actions Inspector