Transcript Septic System Site Evaluations

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.
2.
3.
4.
Replace failed ISTS with new ISTS.
Decentralized cluster system.
Connect to existing facility.
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:
More complete assessment:
Complying
&
Non-complying
Complying
&
‘Could be’ Complying
&
‘Can’t be’ Complying
Typical Assessment
Minnesota Lake
Comply
Don’t Comply
More Complete Assessment
Minnesota Lake
Comply
Could Comply
Can’t Comply
Doing the more complete assessment
• Map of parcels
• Records:
– Permits
– Age of systems
– Maintenance
• Properties to be checked:
– No records
– Possible un-permitted
work
– Older than XX years
– Suspected problems
• Identify:
– Likely compliant
– Spot check
• Map of findings
Septic System Components
Source
Well
Tank
Drainfield
Treatment in Soil
Groundwater
3 feet
Site Assessments: Soil Analysis
Inadequate Vertical Separation
Source
Well
Tank
Groundwater
3 feet
Drainfield
Inadequate Treatment
Pathogens
Nutrients
Source
Mound System
Mound Treatment Area
Well
Tank
Pump
Treatment in Soil
Groundwater
3 feet
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
Site Evaluation
58%
No Site
Evaluation
42%
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
8
1
37
16
In Compliance
Imminent Threat to Public Health
Not In Compliance
No Water
Public Health Threats- Stacked Up
1
8
37
32
16
3
2
NIC
ITPH-TILE
No Water
DRYWELL
IC
SURFACE
Veseli- Overall Septic Situation
1
38
37
16
106
Buildings
Assumed Compliant
Not In Compliance
No Water
14
Curtain Drain
ITPH
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
Field Work $1925
WW
Initiative
$1160
Total
Reporting
$240
$312
$552
Overhead
$408
$270
$678
Mileage
$198
$180
$378
Meals
$0
$75
$75
Total
$2771
$1997
$4768*
* $76.90/ Site Evaluation
$3085
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