Incorporating Basin Technical and Scientific Advisory Committee Recommendations into Local Projects Chad Engels, PE Bois de Sioux Watershed District Engineer 2019 Red River Basin Drainage Conference Marriott Hotel and Convention Center, Moorhead, MN March 19 th , 2019
Overview 1. Bois de Sioux Watershed District (BdSWD) Background 2. Basin Technical & Scientific Advisory Committee (BTSAC) Papers 3. BTSAC Applications for Permitting 4. BTSAC Applications for 103E Public Drainage Systems 5. BTSAC Applications for Watershed Projects 6. Summary 2
BOIS DE SIOUX WATERSHED DISTRICT
Background Bois de Sioux Watershed District Formed in 1988 Headwaters of the Red River 1,412 square mile watershed 6 Counties (9 Water Managers) Administrator, Office Manager, & Technician Major Tributaries: Mustinka & Rabbit Rivers One Watershed One Plan (2 WRAPS Complete) 4
Background 5
Background Rabbit White Rock Dam Mustinka 6
1997 FEMA DAMAGE SITES Background 7
2019 Spring Flood Outlook 8 Snow Water Equivalent – March 17, 2019
BASIN TECHNICAL & SCIENTIFIC ADVISORY COMMITTEE (BTSAC) PAPERS
Volume & Rate Considerations Volume = the amount of water (ac-ft or ft 3 ) Rate (Discharge) = the movement of water (ft 3 /s) Red River Basin floods tend to be volume driven • Extent of flooding in the flat glacial lake plain How does subsurface drainage affect volume? • Potential loss of soil storage (dry soil condition vs. wet soil condition) How does surface drainage affect volume? • Possible addition of previously non-contributing areas • Possible reduction of temporary floodplain storage 10
BTSAC Briefing Papers BTSAC Briefing Paper No. 2 • Water Management Options for Sub-surface Drainage (2012) BTSAC Briefing Paper No. 3 • Water Management Options for Surface Drainage (2014) 11
Briefing Paper No. 3 (Surface) Briefing Paper #3 BTSAC Members (20) Sponsored by the ND RRJWRD and MN RRWMB What are the impacts of ag drainage on peak watershed flows? How should ag drainage systems be designed and managed? 12
Briefing Paper No. 3 Key BTSAC Surface Water Management Statements • Landowners have a right to adequate, but not more than adequate, drainage • Adequate drainage is defined as the capacity to remove a 10-yr 24-hr summer rainfall event without significant crop damage (removal in 24 hrs) • Typical 10-yr rainfall at center of RRB is 3.6 inches in 24 hrs (1.3 inches runoff) • Equal distribution of positive and negative drainage impacts throughout the system is the design goal • “Uniform Surface Drainage Design Guidance” for small watersheds • “Self Mitigating” Design 13
Briefing Paper No. 3 Equal distribution of positive and negative impacts Temporary Floodplain Storage for an Event Exceeding the System Design Oversized Culverts Properly Sized Culverts “Adverse Downstream Impacts” “Self Mitigating Design” 14
BTSAC Briefing Paper #3 “Uniform Surface Drainage Guidance” • BTSAC Design Flow = Q 15
BTSAC Briefing Paper #3 “Uniform Surface Drainage Guidance” – Design Steps • Determine Q for each design location (typically each road crossing) • Design the upstream channel to convey Q with ½ to 1 foot of freeboard • Design the culvert for ½ to 1 foot of headloss • The design water surface profile upstream of crossings should be at field El. • Spoil banks must be lowered to the design El. immediately upstream of crossings • Flap gates (trap gates) are allowed if spoil banks are lowered • Crop damage is expected for events larger than the 10-yr • This design guidance is for small watersheds of relatively flat to moderate slope • Self mitigating design 16
BTSAC Briefing Paper #3 “Uniform Surface Drainage Guidance” Temporary Floodplain Storage 17
BTSAC Briefing Paper #2 (Sub-surface) Water Management Options for Sub-surface Drainage (2012) • Recommends outlet controls for subsurface drainage – Preferred • Recommends “on or off-site” storage alternative (mitigate lost soil storage) • Recommends lower “Drainage Coefficients” (slow release of water from the soil) • Recommends culvert sizing strategy (temporary short term on-channel storage) 18
1998 Mediation Agreement Key Mediation Agreement Statements that “fit” with BTSAC • The broad goals for flood damage reduction in the Basin are: − To reduce damage to farmland by providing protection against the 10-yr storm event for intensively farmed ag land • Culvert sizing is a flood damage reduction strategy − Graduated sizing of culverts in ditch systems provides control − Equity is an important consideration − The smaller the drainage area the more effective culvert sizing becomes 19
PERMITTING
Permitting BdSWD Permitting Authority Private Subsurface Drainage (Tile) Private Surface Drainage Culverts & Bridges Ring Dikes & Levees Alterations to Rivers, Streams, Wetlands, Shorelines, and Roads 21
Permitting Miles of Permitted Drain Tile Since 2000 18,500 miles in past 19 years Significant increase in miles of tile installed over the past 8 years Approx. 25% of the watershed area is now tiled Through 2010 Through 2018 22
Permitting Past 4 Years (2015-2018) 23
BdSWD Permit Policies BdSWD has adopted Basin Technical and Scientific Advisory Committee (BTSAC) Briefing Papers #2 & #3 BTSAC Briefing Paper #2 – Water Management Options for Sub-surface Drainage • Recommends outlet controls for subsurface drainage • Recommends lower “Drainage Coefficients” (slow release of water from the soil) • Recommends culvert sizing strategy (BTSAC Paper #3) BTSAC Briefing Paper #3 – Water Management Options for Surface Drainage • Recommends utilizing culvert and channel design guidance • Recommends maintaining existing non-contributing areas 24
BdSWD Permit Policies (BTSAC) Sub-surface Drainage (Drain Tile) Gravity Outlets - ¼” DC Controlled Outlets – No DC Limitation • Lift Stations • Control Structures All pumps must be turned off and gates closed during all times the District determines flood conditions exist downstream First downstream culvert must conform to BTSAC 10-yr design 25
BdSWD Permit Policies (BTSAC) BdSWD Website Tile Pump Status Webpage • Highlights areas in red where pump restrictions apply within the District EZ Texting Signup • Website where permit applicants can sign up to receive text message alerts regarding pump restrictions 26
BdSWD Permit Policies (BTSAC) Culvert Replacement Permits No permit required for Existing Culvert Design Requirement (BTSAC) Culverts if: • 10-yr BTSAC Design Flow • Proposed culvert has the same • Approx. 1” DC (K = 27) capacity as the existing culvert • 0.5’ – 1.0’ of Head Loss and set at the same grade • Proposed culvert diameter is 18” or smaller All other culvert replacements require a permit from the District 27
103E PUBLIC DRAINAGE SYSTEMS
103E Public Drainage 103E Public Drainage in the BdSWD 586 miles of 103E Ditches 412 miles are under the authority of the BdSWD Grant, Stevens, OtterTail and Big Stone Counties have retained authority 29
103E Public Drainage BTSAC Recommends… “The design guidance should be considered when permitting or improving both public and private surface drainage systems in agricultural areas of the Red River Basin” “Every available opportunity should be utilized to retrofit existing Red River Basin drainage systems using this design guidance” 30
103E Public Drainage BTSAC States… “If the design guidance is applied, and culverts are appropriately sized according to the design guidance throughout the watershed of the drainage system, no further drainage system flood mitigation is needed because the agricultural surface drainage system can be considered self-mitigating ” 31
103E Public Drainage BTSAC Design Elements FLOW 32
103E Public Drainage BTSAC Recommendation: Low Spoil Bank Upstream of Road Crossings 10-yr design breakout 33
103E Public Drainage Channel Design - Typical Cross Section 34
103E Public Drainage Channel Design: Flatten Field Side-Slope Construct Field Berm 20:1 Backslope Grass Buffer 35
103E Public Drainage Const. and Future R/W includes: Permanent Easement Spoil Easement Permanent Easements 103E Buffer Permanent Spoil Easements (also used for construction) 36
103E Public Drainage BTSAC 103E Ditch Retrofits • Traverse Co. Ditch No. 37 (2017) • Wilkin Co. Ditch No. 8 (2018) • Wilkin Co. Ditch Nos. 9 & 10 (2019) • Judicial Ditch No. 11 (2020) • Judicial Ditch No. 6 (2021) • Wilkin Co. Ditch No. 1 (2022) 37
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