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2009 City of Bozeman Storm Water Update. Dustin Johnson, P.E. Project Engineer City of Bozeman . 2009 City of Bozeman Storm Water management update. Design and Development Phase II and related expenses Storm Water Masterplan Storm Water Sampling. City of Bozeman Review Process. - PowerPoint PPT Presentation
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2009 City of Bozeman Storm Water Update
Dustin Johnson, P.E.Project EngineerCity of Bozeman
2009 City of Bozeman Storm Water management update
Design and Development Phase II and related expenses Storm Water Masterplan Storm Water Sampling
City of Bozeman Review Process Preliminary Design City Board Review –
DRC, DRB, Planning Board, City Commission, etc.
Infrastructure Review – City Engineering, DEQ
Approval
Review Criteria
Zoning
Transportation
Growth Plan
Engineering Review
Why are Storm Water facilities necessary?
Flood Control Channel Stability of
Creeks and Rivers Water Quality Potential Re-use of
rain water
Storm water EngineeringPipe sizing and types
Basin sizing
Basin Location
Slope requirements
Calculation formats
COB Runoff CoefficientsRainfall Curves
Floodplain Regulations
Types of Storage/Treatment Facilities
Retention Basins 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.
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
In a perfect world…
Other considerations
Depth of groundwater Other surrounding infrastructure Historic Drainage Patterns Limited Space Facilities not built to specifications Aesthetics Easements
When things start to go wrong…
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
Montana Cities implementing Phase II
Billings & Yellowstone County
Missoula & Missoula County
Great Falls and Cascade County
Butte Bozeman Helena 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
$28,000 $3,100
$203,500 $120,000
$20,000 $49,400 Public Outreach and Ed-ucation
Public Involvement and Participation
Illicit Discharge Detection and Elimination
Construction Site Storm Water Runoff Control
Post-Construction Storm Water Management
Pollution Prevention and Good Housekeeping for Municipal Operation
Total cost of $424,000 for 5 years
Summary of Direct costs for Storm Water Maintenance
Activity CostClean 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
Item CostDirect 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.
Most Recent Sample Results(Taken 11/13/08)
Permit Limits
Above Kagy
Below Tamarack
Storm Langhor
Storm Tamarack
(mg/l) (mg/l) (mg/l) (mg/l) (mg/l)
TSS 125 12 13 60 322
Oil and Grease 10 ND ND 4.5 14
Nitrogen (Total) 2 0.8 0.8 0.8 ND
Phosphorus 0.41 0.09 0.07 0.4 0.91
Zinc 0.21 0.01 ND 0.08 0.18
Lead 0.165 ND ND ND 0.03
Copper 0.04 ND ND ND 0.03
COD 80 14 11 86 27
Nutrients in Storm water vs. Waste water effluent
Total Nitrogen Total Phosphorus
Estimated current effluent removal Quality for WWTP 9 mg/L 3 mg/L
Estimated effluent removal Quality for WRF expansion (phase I) 7.5 mg/L 1 mg/L
Sample taken 7/25/08 at storm drain in Tamarack 1.4 mg/L 2.14 mg/L
Sample taken 7/25/08 in Boz. Creek upstream from Kagy 0.6 mg/L 0.07 mg/L
Sample taken 11/13/08 in Boz. Creek below Tamarack 0.8 mg/L 0.07 mg/L
Going forward from here… Actively working with MSU and other
organizations to explore new options regarding storm water and storm water education.
Questions/Discussion