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An Accurate Assessment of the Situation
Determining a Community’s Wastewater Needs
Nick Haig- University of Minnesota
Onsite Sewage Treatment Program
[email protected] - 612-625-9797
What is a site assessment?
• Analyze records• Determine lot size• Locate well• Probe existing system• Conduct soil boring• Match soils• Determine seasonal
water table depth• Locate potential
drainfield area• Identify treatment
options• Check/pump septic tank
Inspection: Results
1. Certificate of compliance
2. Certificate of non-compliance
3. Imminent Threat to Public Health System (ITPHS)
Local policies affect results and homeowner requirements!BUYER BEWARE!
What about a whole community?
MPCA Unsewered Area Alternative Analysis
1. Replace failed ISTS with new ISTS.
2. Decentralized cluster system.
3. Connect to existing facility.
4. Connect to a facility, which requires an expansion.
5. Construct a new wastewater and treatment facility.
Note: Solution may be a combination of approaches
Determining ‘Decentralized’ Feasibility
Typical assessment:
Complying
&
Non-complying
More complete assessment:
Complying
&
‘Could be’ Complying
&
‘Can’t be’ Complying
Comply Don’t Comply
Minnesota Lake
Typical Assessment
Comply Can’t ComplyCould Comply
Minnesota Lake
More Complete Assessment
Doing the more complete assessment
• Map of parcels• Records:
– Permits
– Age of systems
– Maintenance
• Identify:– Likely compliant
– Spot check
• Properties to be checked:– No records– Possible un-permitted
work– Older than XX years– Suspected problems
• Map of findings
Septic System Components
Source
Tank Drainfield
Treatment in SoilGroundwater
Well
3 feet
Site Assessments: Soil Analysis
Inadequate Vertical Separation
Source
Tank Drainfield
Inadequate TreatmentGroundwater
Well
3 feet Pathogens Nutrients
Mound SystemSource
Tank
Treatment in SoilGroundwater
Well
3 feet
Pump
Mound Treatment Area
What Kind of System is Bad (failing)?
• Leaky Tanks
• Surfacing to Ground
• Inadequate Vertical Separation to Water Table
• Direct Discharge
Drywells or Cesspools
Surfacing to the ground
Direct Discharge (to surface, tile line, or body of water)
Veseli• Examined the records
• Conducted 62 Site Evaluations
• Determined the current status of systems
• Assessed potential solutions for each property
• Evaluated potential cluster sites
• Produced map of findings
• County cost for time, travel, reporting and some overhead - $76.90/site
Results
106 Homes or Businesses
58%
42%
Site Evaluation
No SiteEvaluation
Possible Results
• “In Compliance”- Meets current Rice Co. Ordinance
• “Not In Compliance”- Does not meet current Rice County Ordinance, may need to be upgraded in the future
• “Imminent Threat to Public Health System”- ground surface or surface water discharge, sewage backup into dwelling, drywell or cesspool.
Results• 60 Anticipated Site Evaluations• 62 Final Site Evaluations
• About 60% of community needed to be inspected because of:
No records Unpermitted work Suspected direct discharges
• Several homes have been upgraded since 1992 due to Rice County Septic Ordinance property transfer requirements
Actual Results8
3716
1
In Compliance
Imminent Threat to Public Health
Not In Compliance
No Water
3716
1 8
3
2
32
NIC No Water IC
ITPH-TILE DRYWELL SURFACE
Public Health Threats- Stacked Up
Veseli- Overall Septic Situation1
37
16 14
38
Assumed Compliant Curtain Drain
Not In Compliance ITPH
No Water
106
Buildings
Veseli- Overall Septic Compliance
Community Options(in no particular order)
• Regionalize to Lonsdale (2002 est. = $30,000)
• One “decentralized” collection/treatment system for entire community
• Several “cluster” collection/treatment systems for entire community
• Upgrade all “non-compliant” systems with ISTS and cluster those that cannot fit ISTS
Options (cont.)
• Upgrade systems that pose ITPH with ISTS and cluster where necessary
• Allow new developments but require them to provide wastewater treatment for existing lots currently not in compliance
Site Evaluation Conclusions
Site Evaluation Cost Estimates
Rice County
WW Initiative
Total
Field Work $1925 $1160 $3085
Reporting $240 $312 $552
Overhead $408 $270 $678
Mileage $198 $180 $378
Meals $0 $75 $75
Total $2771 $1997 $4768*
* $76.90/ Site Evaluation
Beaver Lake
Individual “standard” system
Individual “other” system or a holding tank
Individual holding tank
Cluster system
Costs- Beaver Lake
• $500 to local ISTS professional
• In Kind not counted
• $3000-$5000 estimated
Meriden
More complete assessment
• Offers a complete understanding of the current situation
• Basis to look at potential solutions
• Helps determine appropriate boundaries
• Fits with the funding hierarchy changes