Types of Storage/Treatment Facilities Retention Basins Designed to retain all runoff from a 10 year, 2 hour storm. Designed to retain all runoff from a 10 year, 2 hour storm. Detention Basins Release water through controlled outlet structure, at no greater than pre-development runoff. Release water through controlled outlet structure, at no greater than pre-development runoff.
Retention Basins Calculations based on the Rational Formula Q = CiA (cfs) V = 7200Q (cubic feet) i for Bozeman 10 year, 2 hour storm always =.41 in/hr
Detention Basins More complicated than Retention Basins Determine Tc, i @ Tc, and Q of pre- development runoff Determine Tc and i @ Tc of post- development runoff Determine maximum storage volume at various storm lengths for 10 year storm Determine size of discharge structure
Local Examples of Storm Water Management The Good
Local Examples of Storm Water Management The Bad
NPDES Phase II National Pollutant Discharge Elimination System Federal EPA regulated by Montana Department of Environmental Quality The purpose is to reduce or eliminate potential storm water pollutants from reaching water resources such as streams and lakes.
Who is permitted for Phase II in Bozeman? Continued partnership with MSU and MDT as co-permittees on MS4 Phase II.
Storm Water Hierarchy Storm Water in Bozeman MT Phase II Permit Post Construction Runoff control UDO edits Finding funding Sources Public Education Public Meetings And Feedback Pollution Prevention And BMP’s Storm water Masterplan Updated Codes And Regulations Construction Site Runoff control Inspection and Enforcement Illicit discharge Detection and Elimination Storm Water Sampling City of BozemanMDT MSUGLWQD
Montana Cities implementing Phase II Billings & Yellowstone County Billings & Yellowstone County Missoula & Missoula County Missoula & Missoula County Great Falls and Cascade County Great Falls and Cascade County Butte Butte Bozeman Bozeman Helena Helena Kalispell Kalispell
Phase II 6 Minimum Control Measures (MCM) Public Education and Outreach Public Involvement/Participation Illicit Discharge Detection and Elimination Construction Site Runoff Control Post Construction Storm Water Management Pollution Prevention and BMP’s
Total Minimum 5 year Direct Costs for Phase II Total cost of $424,000 for 5 years
Summary of Direct costs for Storm Water Maintenance ActivityCost Clean Storm Sewer Facilities and Ditches$30,731 Repair Storm Sewer System$8,860 Leaf Cleanup$32,650 Street Sweeping$108,624 Miscellaneous$9,739 TOTAL$190,604 All costs based on 2005 estimates taken from COB Storm Water Masterplan
Estimated Total Future Storm Water Costs ItemCost Direct Operational Cost$191,000 Phase II Implementation$100,000 Capital Improvements$200,000 Indirect Costs (20% of total)$98,000 Total Cost per Year$589,000 All costs based on 2005 estimates taken from COB Storm Water Masterplan
Where are we today with Phase II Completed year four of a five year permit Required semi-annual storm water sampling Continue working with our co-permitees MSU and MDT New engineering standards Updated public information Completed Storm Water Masterplan
Storm Water Masterplan Adopted by City Commission late 2008 Is available for public review and use
Masterplan Breakdown Existing System Inventory System Analysis Policy Evaluation NPDES Phase II Permit Compliance Financial Management Evaluation Recommended Plan
Significant Recommendations of the Masterplan Move forward in establishing funding source for storm water. Establish uniform approach to development submittals. Continue relying on development-based storm water management until Phase II guidelines are more advanced.
Storm Water Sampling Started sampling storm water in Bozeman in 2007. As with all Cities in Montana, the results were mixed. Too early to get anything definitive from one sampling.
Nutrients in Storm water vs. Waste water effluent Total NitrogenTotal Phosphorus Estimated current effluent removal Quality for WWTP 9 mg/L3 mg/L Estimated effluent removal Quality for WRF expansion (phase I) 7.5 mg/L1 mg/L Sample taken 7/25/08 at storm drain in Tamarack 1.4 mg/L2.14 mg/L Sample taken 7/25/08 in Boz. Creek upstream from Kagy 0.6 mg/L0.07 mg/L Sample taken 11/13/08 in Boz. Creek below Tamarack 0.8 mg/L0.07 mg/L
Going forward from here… Actively working with MSU and other organizations to explore new options regarding storm water and storm water education.