Fort Leonard Wood, Missouri September 2013 1
Presenters Shannon Kelly, Physical Scientist Clean Water Act Program Manager Directorate of Public Works Environmental Division Environmental Compliance Branch Fort Leonard Wood, MO John K. Denlinger, P.E. CFM Water Resources Section Manager HDR Engineering, Inc. Kansas City, MO 2
Mission Home to U.S. Army Garrison Fort Leonard Wood Home to the Maneuver Support Center of Excellence One of Five Reception Stations in the Army Significant Training Operations TA 244 Joint Engineer Operators Course 3
Fort Leonard Wood Installation 4
5
Smith Branch Watershed ~ 13 square miles Training Area (TA) 244 6
76 stormwater basins Sediment control Stormwater detention Recreation opportunities 54 basins > 0.1 acre footprint 7
76 stormwater basins Sediment control Stormwater detention Recreation opportunities 54 basins > 0.1 acre footprint 8
76 stormwater basins Sediment control Stormwater detention Recreation opportunities 54 basins > 0.1 acre footprint 9
Non-Point Source Stormwater Studies Objective: to evaluate a number of basins, features, and Installation activities and determine their impacts on stormwater volume and quality and to ensure compliance with the Missouri Clean Water Law. 10
1. Evaluate adequacy of existing basins 2. Support stormwater permit compliance 3. Establish goals & objectives 4. Formulate alternatives 5. Develop recommendations for implementation 11
Watershed evaluation Land use conditions Training activities Functionality of existing basins 12
Visual site inspections Checklists, photos, measurements Identify deficiencies Topographic surveys Sediment depth measurements Inflow/outflow structure dimensions 13
Model capabilities Graphical-user interface Comprehensive, expandable modeling platform Hydrology, hydraulics, water quality BMP simulations Watershed Model Selection EPA SUSTAIN System for Urban Stormwater Treatment and Analysis Integration XP-SWMM XP Software, Storm Water Management Model 14
Input parameters Hydrologic Hydraulic Sediment Hourly precipitation Subwatershed areas Land use Soil type Land slope Conveyance channels Sediment basins Spillways Overflow routes Roughness coefficients Land use Event mean concentration Sediment particle size BMP data 15
Precipitation data Hourly, continuous data for typical year...1990 Not event-based (e.g. 10, 50, 100-year) Rainfall intensity is critical to sediment generation Selection of typical year considered both: Rainfall intensities Rainfall totals 16
Sediment basins Available storage capacities Stage-storage-discharge functions 17
Link-node structure Each node represents a stormwater basin GIS compatible 18
Northern Network 19
Southern Network 20
What have we learned? TSS contributions throughout watershed Effectiveness of existing stormwater basins Life expectancy of existing stormwater basins Technical support for alternatives development 21
Volume Deficiency (ac-ft) 22
Remaining Serviceable Life (yrs) 23
Goals & objectives Stormwater runoff and sediment management Stormwater permit requirements (Fort Leonard Wood site-specific Industrial Stormwater Operating Permit) Potential future stormwater permit requirements Energy Independence and Security Act (EISA) 2007 Section 438 24
EISA Section 438...establishes stormwater runoff requirements for all federal development and redevelopment projects to protect water resources. Not a requirement for FLW TA 244 Used as a performance target 95 th percentile rainfall event (1.55 in) 25
Alternatives formulation USACE six-step planning process Management measures Cost-effective solutions Management Measure Sediment Management Runoff Management Water Quality Benefits Habitat Opportunities Existing Basin Modification - - - - Renovation - - - - Sediment Removal & Disposal Infrastructure Modification Stabilization Retrofitting Enlargement Existing Basin Removal New Basin Construction Erosion Control Measures Non-structural Measures Highly Beneficial Marginally Beneficial Neutral 26
1. No action Alternative Summary 2. Repair of critical issues (8 basins improved) 3. Repair of critical issues Corrective action to basins with less than 10 years life remaining (16 basins improved) 4. Individual basin solutions to meet 95 % volume requirements (33 basins improved) 5. Cumulative approach to meet 95% volume requirements (41 basins abandoned, 3 new, 10 improved) Measures Common To Alternatives 2 through 5 Basin Retrofitting use of native vegetation lengthened flow patterns multi-staged outlets reduced impervious connectivity On-Site Erosion Control Measures silt fence, bale/rock checks stabilized entrances/exits Non-Structural Measures continued training education (FLW personnel & public) Ongoing O&M 27
Short-term: Alternative 2 Address critical issues at 8 basins Retrofitting, on-site erosion control, non-structural Ongoing O&M Long-term: Alternative 5 Regional basin solution 16 strategically-located basins 28
29
Fort Leonard Wood, Missouri September 2013 30