11th International Drainage Symposium August 30-September 2, 2022 Des Moines, Iowa

1. Architecture + Engineering + Environmental + Planning | ISGInc.com
HYBRID
DRAINAGE
Practices to ImproveWater Quality
Bethany Brittenham, PE
Water Resources Engineer
2022 International Drainage Symposium
Spencer Pech, EI
Graduate Engineer

2. Architecture + Engineering + Environmental + Planning | ISGInc.com
ISG Representatives
Bethany Brittenham, PE, Water Resources Engineer
515.243.9143 | Bethany.Brittenham@ISGInc.com
Spencer Pech, EI, Graduate Engineer
712.732.7745 | Spencer.Pech@ISGInc.com

3. Architecture + Engineering + Environmental + Planning | ISGInc.com
Firm Overview
Business Units
Commercial
Education
Food
+ Industrial
Government
+ Cultural
Healthcare
Housing
Mining
PublicWorks
Sports
+ Recreation
Telecommunications
+ Energy
Transportation
Water
450+ Multi-Disciplinary Professionals
11 Midwest Offices

4. Architecture + Engineering + Environmental + Planning | ISGInc.com
Case Study Challenges
Nutrient
Loss
Lost
Production
Aging
Infrastructure
Case Study Conditions:
• Large multi-landowner
systems with a county-level
board
• Drainage coefficient
unsuitable for modern farming
practices
• No water quality regulations
• Multiple stakeholder groups

5. Architecture + Engineering + Environmental + Planning | ISGInc.com
Hybrid Project Solution
Treatment
Wetland
Wildlife
Habitat
Update
System

6. Architecture + Engineering + Environmental + Planning | ISGInc.com
Case Study Locations
BuenaVista County
Kossuth County
Osceola County
Site Locations

7. Architecture + Engineering + Environmental + Planning | ISGInc.com
Site 1: BuenaVista County
• “Youngest” System
~100 years old
• FiveTotal Districts
• Four Interior Districts
• Restricted Outlets

8. Architecture + Engineering + Environmental + Planning | ISGInc.com
Existing Conditions
Summer 2013
July 2015
May 2016
April 2018

9. Architecture + Engineering + Environmental + Planning | ISGInc.com
Project Alternatives
Standard Drainage Solutions
Limitations
• Ditch grade
• Cost
• Stakeholder engagement
Hybrid Solution
Limitations
• Stakeholder engagement
• Funding
Main Open
Ditch Extension
Open Ditch
Cleanout

10. Architecture + Engineering + Environmental + Planning | ISGInc.com
Site 2: Kossuth County Drainage District No. 75
• Des Moines Lobe
• ~1,600 Ac Watershed
• Originally constructed in 1913
• Outlets to East Fork Des Moines
River floodplain
• ~19% of 1/2” Dc at outlet,
20-30% throughout system
• USFWS property
• Engaged landowners

11. Architecture + Engineering + Environmental + Planning | ISGInc.com
Tile Improvements + Design Options
Tile Improvements + Design Options
• 1/2” or 3/4” Dc
• Open ditch outlet
• MainTile and Lateral 1
• Additional lateral improvements
• Opportunities for water quality
improvement and alternative
design
Design Alternative:
Nutrient Reduction Wetland
• Breakpoint-style wetland
• Outlet district tiles
• Surface drainage channel
• Topographic limitations

12. Architecture + Engineering + Environmental + Planning | ISGInc.com
Site Design
March 2021

13. Architecture + Engineering + Environmental + Planning | ISGInc.com
Alternative Project Funding
Multiple entities
involved
Anticipated low
interest
• Compared to
Drainage Bonds (5%)
Finance district
drainage and
wetland costs
District
investment
in wetland
• Alternative funding
for remainder
Up to 20-year loan
payback
Construction and
interest savings
Up to $480K in
potential savings

14. Architecture + Engineering + Environmental + Planning | ISGInc.com
Site 3: Osceola County JDD3 Branch 152
• ~4,400 Ac Watershed
• Originally constructed in 1917
• Historical Chain Lake basin
• ~20-30% of recommended capacity
throughout system
• Multiple branches considered
• Significant drown outs
• Engaged landowners

15. Architecture + Engineering + Environmental + Planning | ISGInc.com
Drainage Improvements + Challenges
• Large tile sizes
• Ditch not feasible
• Extremely high cost (>$1,200/AC)
• Grade available
• Higher coefficients considered

16. Architecture + Engineering + Environmental + Planning | ISGInc.com
Storage Pond-Style Wetland

17. Architecture + Engineering + Environmental + Planning | ISGInc.com
ICM Model Results

18. Architecture + Engineering + Environmental + Planning | ISGInc.com
Solutions
• Roughly $200/Ac
in savings
• Water quality benefit
• Outlet peak flow reductions
• Surface flow reductions
• Free flowing outlet for
upstream lands
• Potential for drainage
water recycling

19. Architecture + Engineering + Environmental + Planning | ISGInc.com
Challenges
Site Suitability/Topo
Wetland Landowner Interest
District Landowner Interest
Agency Coordination

20. Architecture + Engineering + Environmental + Planning | ISGInc.com
THANK YOU!
Bethany Brittenham, PE, Water Resources Engineer
515.243.9143 | Bethany.Brittenham@ISGInc.com
Spencer Pech, EI, Graduate Engineer
712.732.7745 | Spencer.Pech@ISGInc.com

21. Architecture + Engineering + Environmental + Planning | ISGInc.com
Project Solution:Treatment Wetland