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Of nearly 12,000 rural well samples submitted to the University of Iowa Hygienic Laboratory each year, 35 - 45% are found to contain unsafe levels of total coliform bacteria, and 15-20% exceed the US Environmental Protection Agency health advisory level for nitrate-nitrogen.

Health authorities and well contractors point out that a properly constructed well and plumbing system are the most effective way for rural Iowans to protect their drinking water. But a new well can cost thousands of dollars, so owners of contaminated wells frequently ask about repairs that can correct contaminated water. The following summarizes the content of 14 slides contained in a "Power Point" presentation developed by Dr. Tom Glanville, Department of Ag and Biosystems Engineering, Iowa State University for a three-day workshop for County Sanitarians and Environmental Specialists. The "Private Water Well Systems" workshop, sponsored by the Iowa Department of Public Health and Kirkwood Community College will be held on October 2-4, 1995 at the Environmental Training Center, Kirkwood Community College, Cedar Rapids, Iowa.

Iowa County Extension Offices and others interested in obtaining a copy of this presentation for use in their environmental educational programs may obtain a complete copy of the Well Assessment & Repair Power Point Presentation (332K) by clicking here (Note: You must have the Microsoft Power Point software or a Power Point viewer to view and use the presentation).

============================================== Well Assessment & Reconstruction

==============
Private well problems in Iowa

• According to statewide rural well survey
• 45% have unsafe total coliform
• 18% exceed EPA MCL for nitrate
• 13% contain detectable levels of one or more pesticides

==============
Can my well be repaired?

• If coliform bacteria the ONLY problem.....maybe.....depends on:
• Depth of well?
• Structural integrity of well

==============
Can my well be repaired?

• If high nitrate levels....probably NOT
• Often due to vulnerable geology, poor well location, inadequate depth
• IF well is deep, serious casing defects may be as costly to repair as constructing a new well

==============
Can my well be repaired?

• If pesticides are a problem....probably NOT
• often caused by vulnerable geology or a spill
• neither can be fixed by simple well repair

==============
Poor candidates for repair

• Wells less than 20 feet deep
• Wells tapping fractured bedrock aquifers capped by less than 20 feet of soil
• Wells that are structurally weak (casing deteriorated)

==============
Pathways for bacterial
entry into wells

• Loose or missing well caps
• Flooded frost pits
• Leaky casing materials - concrete or clay tile, brick, rock
• Leaky "pitless" equipment
• Unplugged abandoned well nearby (at similar depth)

==============
Typical well repairs

• Tighten or replace well cap
• gasketed cap with screened vent recommended
• Replace pitless equipment
• Remove frost pit ...extend casing...install pitless equipment
• Replace top 10-15 feet of tile well with watertight plastic casing and gasketed cap (buried slab method)

==============
"Pathways" for bacterial entry into concrete tile wells

==============
Renovating bacterially -contaminated wells

• Goal: Make top 10 feet of casing water-tight
• soil a pretty good bacteria "filter"
• try to insure that water is "filtered" before it can enter the well
• Goal: well should be tightly capped

==============
Renovation of tile well using
"buried slab" method

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"Pathways" for bacterial entry into drilled wells
==============
Renovation of well located in frost pit

============== Well Renovation

• Best chance for success IF bacterial contamination is the ONLY problem
• "Risky" for very old wells as they often suffer from multiple defects
• Seek advice (and bids) from more than one contractor
• If repair cost exceeds 1/2 the cost of a new well... new construction may be a better investment

==============
For Further Information

Repairing Bacterially Contaminated Wells by Tom Glanville and Shawn Shouse, Department of Agricultural & Biosystems Engineering, Iowa State University, June 1994. (available through County Extension Offices)

Well Reconstruction and Repair (8-minute video tape funded by Iowa Department of Agriculture and Land Stewardship) by Shawn Shouse and Tom Glanville, Department of Agricultural and Biosystems Engineering, Iowa State University, May 1994. (available through County Extension Offices)

Water Well Construction: A Consumer Information Booklet, by Iowa Department of Natural Resources and Iowa Department of Public Health, April 1993.

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