An Accurate Assessment of the Situation��Determining a Community’s Wastewater Needs

Nick Haig- University of Minnesota

Onsite Sewage Treatment Program

haigx003@umn.edu - 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

​

• Certificate of non-compliance

​

• 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 Comply

Could 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 Soil

Groundwater

Well

3 feet

Site Assessments: Soil Analysis

Inadequate Vertical Separation

Source

Tank

Drainfield

Inadequate Treatment

Groundwater

Well

3 feet

Pathogens

Nutrients

Mound System

Source

Tank

Treatment in Soil

Groundwater

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

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 Results

Public Health Threats- Stacked Up

Veseli- Overall Septic Situation

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

​

​

* $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