Introduction Mike Opat, PE Project Manager 17+ years of experience - PDF document

Lake Shamineau High Water Outlet Lake Shamineau High Water Outlet Informational Meeting Informational Meeting August 6, 2020 August 6, 2020 LAKE SHAMINEAU LAKE IMPROVEMENT DISTRICT LAKE SHAMINEAU LAKE IMPROVEMENT DISTRICT 1 Introduction  Mike Opat, PE – Project Manager  17+ years of experience  Managed numerous high water outlet projects  Managed the recently completed Little McDonald, Kerbs & Paul Lake Improvement District’s outlet project near Perham, MN  Role: Assist the Lake Shamineau Lake Improvement District with the development of a permanent outlet that will mitigate the ongoing high water problems around the lake.  Currently focused on stakeholder outreach and system capacity analysis  The HEI team has successfully completed many similar high water outlet projects in the region.  HEI also has extensive experience working with ditch authorities throughout MN  We design projects, we don’t build them. 2

Agenda  Review current scope of services and status  System capacity analysis  Project features  Pump station  Filters  Route  Downstream considerations  Estimated costs  Next steps  Questions 3 HEI’s current scope of services  System Capacity Analysis:  Provide guidance to LSLID on pumping rates required to meet drawdown goals  Investigate downstream waterways to determine capacity to handle additional flows  Develop concept plan for pumping filtered water to County Road 203 ditch  Prepare preliminary concept level cost estimates  Prepare report  Stakeholder Outreach:  Assist the LSLID with initial outreach with regulatory agencies, landowners and the public  Participate in informational meeting and annual meeting 4

HEI’s current scope of services  Work Completed To-Date:  Topographic survey of downstream waterways and other features  Pumping rate analysis  Downstream waterway capacity analysis  Outlet concept plan  Preliminary concept level cost estimates  Report  Assisted the LSLID with initial outreach with regulatory agencies, landowners and the public 5 Pumping Rate Analysis  Common Terms:  Cubic feet per second (cfs)  Gallons per minute (gpm)  Gallons per day (gpd)  Million gallons per day (mgd)  1 cfs= 448.8 gpm  1cfs= 0.646 mgd; 1 mgd= 1.86 cfs 6

Pumping Rate Analysis  2018 HEI report:  Recommended 20 cfs pumping rate (~13 mgd)  High level  No groundwater testing, monitoring or modeling  Utilized available data and broad assumptions  Intended to provide the LSLID with a maximum rate and associated ceiling for costs  Conservative  evaporation not factored in, groundwater assumptions  Assumed 180 days to draw the lake down (to 1’ below OHW)  12 cfs to maintain current lake level + 8 cfs to evacuate excess water= 20cfs 7 Pumping Rate Analysis  2019 Widseth report:  Recommended 10 cfs pumping rate (~6.5 MGD)  Based on maximum annual increase in water levels (1.7 feet in 2014)  Assumed 150 days to draw the lake down 1.7 feet 8

Pumping Rate Analysis  2020 HEI analysis:  Closer look at evaporation and groundwater  High level review  No groundwater testing, monitoring or modeling  Utilized available data and general assumptions  Intended to provide the LSLID with a maximum rate and associated ceiling for costs  Conservative estimate  Evaporation from lake surface accounted for (with assumptions)  Estimated groundwater inflow rates and volumes included  Based on assumed soil types and groundwater contribution area 9 Pumping Rate Analysis  2020 HEI analysis:  Baseline pumping rate to maintain current lake level: ~7 cfs  Average annual runoff from contributing watershed: ~6 cfs  Assumed maximum groundwater inflow rate: ~1 cfs  Additional capacity to evacuate excess water:  LSLID Board goal: Draw the lake down to OHW in 3-4 years  Goal supported by local DNR staff  Multiple drawdown periods (years) and annual operation periods (months/year) were analyzed  Account for maintenance, high water conditions downstream; assume cold weather operation 10

Pumping Rate Analysis  2020 HEI analysis: Period 1 Year Drawdown Operation Time 6 months 9 months Pump Rate, cfs 21 14  Pumping scenarios  Pump Rate, gpm 9,500 6,500 Pump Rate, mgd 13.7 9.4 Period 2 year Drawdown Operation Time 6 months 9 months Pump Rate, cfs 15 11 Pump Rate, gpm 6,900 4,800 Pump Rate, mgd 9.9 6.9 Period 3 Year Drawdown Operation Time 6 months 9 months LSLID Board focusing on Pump Rate, cfs 13 9.3 10 cfs at this time Pump Rate, gpm 6,000 4,200 Pump Rate, mgd 8.6 6.0 Period 4 Year Drawdown Operation Time 6 months 9 months Pump Rate, cfs 12 8.7 Pump Rate, gpm 5,600 3,900 Pump Rate, mgd 8.1 5.6 11 Downstream Capacity  HEI completed a preliminary look at the capacity of the waterways and road crossings downstream of the pipe outlet  Assumed average flow conditions (~ culverts half full)  Looked at a range of potential discharges from project  Impacts appear to be less than one foot at most locations with a 10 cfs pumping rate  Acceptable to landowners that we have met with  Impacts will be addressed through potential improvements (i.e. larger culverts) and through conditions in the Operating Plan 12

Project Features • Intake • Pump Station • Pump • Filter • Building • Forcemain (Pipe) • Outlet • Downstream • Bypass 13 Project Features  Intake:  Gravity flow pipe (extending +/- 100’ into Lake Shamineau)  Intake structure with screen  No suction  Pump Station:  Pump- ~ 100 hp (10 cfs)  Mechanical filter(s)- Filtration currently required by DNR due to Eurasian LMKP Intake Structure (https://www.lmkp-lid.com/) watermilfoil  Building- Necessary for cold weather operations; will provide noise dampening and additional security 14

Project Features  Forcemain:  16” diameter pressurized pipe, buried  Air release valve required  Installed within public road right-of-way when feasible  Outlet:  Pipe will discharge into an energy dissipation structure on the south side of County Road 203.  Erosion control will be installed (e.g. riprap)  Water will transition into recently cleaned out ditch and flow through existing culvert under US Highway 10 15 Project Features  Downstream Considerations:  Possible bypass at existing small private dam along natural flow path  Potential crossing improvements to address landowner and/or township concerns  LSLID to petition Todd County to discharge into Todd County Ditch No. 41 through outlet fee process  Design and operation conditions may arise through this process  Impacts will be addressed through potential improvements (i.e. larger culverts) and through conditions in the Operating Plan  The Operating Plan will be a condition placed on the DNR permit for the project 16

Estimated Project Costs  Concept level design  Concept level cost estimates  Estimates will be refined as level of design increases  Reference recently constructed similar projects (LMKP LID, etc)  Focus on higher cost items (pumps, filters, etc)  Two system capacities (10 cfs & 16 cfs) estimated to provide a range of costs for consideration (i.e. cost vs. drawdown period)  Estimates include a contingency in the budget to account for uncertainties involved with the concept level design and unknowns that might come up 17 Estimated Project Costs  Costs include estimates for all anticipated costs; including construction, engineering, right-of-way, permitting, utilities, legal, administration, etc.  The construction estimates are based on recent bids submitted by contractors on similar projects. A better picture of the actual cost of the LSLID project won’t be known until the project is let for bids.  Actual costs could vary from estimates as market conditions, weather conditions, construction schedules, and other factors all impact the bids submitted by contractors. 18

Estimated Project Costs  Total Estimated Project Cost (10 cfs) :  Preconstruction Phase Costs: $435,000  Construction Phase Costs: $3,350,000  Included contingency amount: $394,500  Total Project Cost: $3.785 million  The current focus is on a 10 cfs system. A 16 cfs option was estimated to cost approximately $400,000 more. 19 Estimated Project Costs  Key Cost Factors:  Dewatering: Required for intake installation, wet well construction, pipe installation; Costs will vary depending on contractor’s desired means and methods, weather conditions, ice, etc; costs from similar LMKP LID project used  Filtration: Mechanical filters assumed, natural filtration options can be further vetted during design phase; Mechanical filters provide potential for resale if DNR determines filters are not required in the future LMKP Intake Installation (https://www.lmkp-lid.com/)  System Capacity: Costs currently reflect a 10 cfs system and will be refined during design phases 20