Feasibility of Bass Lake
Wastewater Treatment
Prepared by Stantec Consulting Services
June 2017
Introduction
• Sanitary District
• Formation
• Powers
• Feasibility Study
• Purpose
• Scope
• Results
Sanitary District - Creation
Wis. State Statute 60.70
Town Sanitary Districts
• Town Board has authority to establish a Sanitary District
• If the Sanitary District is in more than 1 Town, the Town with the
greatest equalized value has “exclusive jurisdiction to establish the
Town Sanitary District”
• Or, by petition of 51% of persons owning land or 51% of land mass
owners
• DNR may order creation of a Sanitary District
• DNR would designate which properties to be included
• Town Board may then order the establishment, if not, the DNR would
establish the boundaries
Sanitary District – Board of Commissioners
Wis. State Statute 60.70
Town Sanitary Districts
• Three Commissioners, each a 2 year term, would be appointed
by the Town Board (Term length would later change)
• May be appointed or elected
• If elected, election would be in April
• If elected the Town Board may not change back to appointed except by a
referendum
• Must be residents of the Sanitary District
Sanitary District – Powers and Duties
Wis. State Statute 60.70
Town Sanitary Districts
• Commission has charge of all affairs of the Sanitary District
• May sue or be sued
• May enter into contracts
• Compensation set by Town Board
Sanitary District – Powers and Duties
Wis. State Statute 60.70
Town Sanitary Districts
• Commission may project, plan, construct and maintain:
•
•
•
•
•
Water System
Solid Waste Collection
Sewage System
Drainage Improvements
Sanitary, Surface, and Storm Water Sewers
Sanitary District – Specific Powers
Wis. State Statute 60.70
Town Sanitary Districts
Sanitary District may:
• Sell any of its service to users outside of corporate limits
• Require installation of Private Onsite Wastewater Treatment
Systems (POWTS)
• Require inspection of POWTS
• Provide direct financial assistance
• Issue orders
• Fix and collect charges
Sanitary District – Specific Powers
Wis. State Statute 60.70
Town Sanitary Districts
Sanitary District may:
• Levy Special Assessments
• Lease or acquire property
• Sell or dispose of property
• Enact Ordinances
• Let contracts for work
• Borrow money and issue Municipal obligations
Rehabilitation District Sanitary District
Wis. State Statute 33.22(3)(a)
Sanitary Districts
May have the power of a town sanitary district if:
• By authorizing resolution of a Town Board having the largest
equalized value portion of the Sanitary District
• Shall possess the powers of the Town Sanitary District that are
authorized by resolution by the Annual Meeting of the
Rehabilitation District
Feasibility Study
• Reason: MnDOT Mitigation Funds available
• Purpose: investigate costs of centralized wastewater
collection and treatment options
• Examined existing conditions
• Analyzed two collection options and three treatment
alternatives
Existing Conditions
• Topography varies greatly
• Groundwater generally moves
from east to west
• Bass Lake is an Outstanding
Resource Water (ORW)
• Total phosphorous in lake has
been gradually increasing
• Highway 64 bridge may
increase development
Existing
Conditions
• 215 homes near Bass Lake, 129
are within “shore zone”
• Project could be constructed in
three phases
• 85 homes in Phase 1, 22 in
Phase 2, 22 in Phase 3
• Homes beyond the shore zone
could be served in the future
Wastewater Flows
Parameter
Phase 1
Phase 2
Phase 3
Average Flow, gpd
13,000
3,500
3,500
20,000
Wet Weather Flow,
gpd
14,500
3,750
3,750
22,000
10
10
Peak Hour Flow,
gpm
40
• Normal, domestic strength wastewater
• No commercial or industrial wastewater
Total
60
Collection System
• Two options: conventional gravity sewer or pressure sewer
system.
• A pressure system would be more cost effective due to:
• Varied topography
• Some homes near the lake at low elevation
• Distance from homes to road
Pressure Sewer System
• Small diameter pressure
piping 1 ¼” to 4” diameter
• Individual grinder pump station
at each home
Pressure Sewer
System
Residential Pump Station
Effluent Limits
• Bass Lake and the St. Croix River are Outstanding Resource
Waters (ORW)
• Fewer than 1% of Wisconsin’s waters are ORWs.
• Requested effluent limits for Willow River, Apple River, St Croix
River from Wisconsin DNR
• Effluent limits are prohibitively stringent for surface waters
• Discharge to nearby surface waters is not a feasible option.
Treatment Alternatives
• Three options:
• Conveyance to Somerset WWTF
• Conveyance to New Richmond WWTF
• Construct a new wastewater treatment facility
• For all three options, the collection system cost remains
the same.
Conveyance to Neighboring Town
• Collection system would discharge to a main pump station.
• Somerset would require about 6.5 miles of forcemain
• New Richmond would require about 7 miles of forcemain
• Both neighboring WWTFs capable of treating additional flows from
Bass Lake area
Construct New WWTF
• Proposed facility would utilize a membrane bio reactor (MBR)
process
• Combines proven biological process with membrane filtration
• The facility would discharge high quality effluent into three
infiltration basins.
Construct New WWTF
• Facility would require approximately 4 to 5 acres
• This option would require further geotechnical investigation
• Must obtain discharge permit from WDNR
Operations, Constructability, and Implementation
• Collection System
• Part time operator
• Need permission, easements
on each property
• Treatment Options
• Conveyance
• Disturbs large area
• Highway & railroad
crossings
• Agreement with city
• New WWTF
• Facility Ownership
• Part time operator
• Maintenance and repair
• Hauling biosolids
Cost Estimates
Collection
Phase 1
Phase 2
Phase 3
$3.0 million
$3.9 million
$4.9 million
Cost Estimates
Conveyance
to Somerset
Conveyance
to New
Richmond
Construct
New WWTF
Collection
$4.9 million
$4.9 million
$4.9 million
Treatment
$4.7 million
$5.2 million
$1.7 million
Total Capital
$9.6 million
$10.1 million
$6.6 million
Annual O,M&R
$165,000
$120,000
$120,000
• Estimates include all three phases
Cost Per Household
Collection and
New WWTF
Total Capital
$6,600,000
Annual Debt Service*
$303,000
Annual O,M & R
$120,000
Total Annual Cost
$423,000
Cost per Household
$3,300/year
*Based on 40-year loan at $3.375%
Funding
• Wisconsin DNR Clean Water Funding Program
• Hardship Assistance – median household income too high
• Small Loans Program – Limited to projects <$2 Million
• Pilot Project Program – NA, meant for innovative treatment
• USDA
• Grants – not eligible, median household income too high
• Loan – 40 year repayment (current rate 3.375%)
Summary
• Purpose: Investigate feasibility and estimate costs for WW
collection and treatment
• Pressurized collection system more cost effective than
conventional
• Constructing and owning a WWTF has the lowest cost of the
options evaluated
• A centralized wastewater treatment system will help protect
Bass Lake’s high water quality for fishing, wildlife, and
recreation
Questions?