Treating Around Wells & Cisterns

When applying a termiticide to soil around foundations of a structure to control subterranean termites, PCOs must take extra precautions to guard against accidental contamination of wells and cisterns on the property being treated, as well as those of neighboring properties. The following is a general description of precautions to take prior to treatment to prevent well contamination, as well as application methods to consider during the process.

REGULATIONS. Before treating to control subteranean termites in a structure which has a well or cistern on the property, PCOs are advised to consult the following materials produced by the National Pest Control Association (NPCA):

Technical Release No. ESPC 055005A (11/25/87) "Termite Treatment of

Existing Structures with Wells or Cisterns."

Technical Release No ESPC 055001 (12/6/79) "Good Practice for Treating

Existing Structures with Wells or Cisterns Close to/Within Foundation."

Approved Reference Procedures for Subteranean Termite Control.

These publications are available from the NPCA, 8100 Oak Street, Dunn Loring, VA. 22027, 703/573-8330.

The PCO should be aware of federal and local FHA/HUD regulations or ordinances regarding soil treatments for termite control. The Minimum Property Standards (MPS) of the Federal Housing Authority (FHA) apply to proposed construction only, not existing structures. These standards are also followed by FHA and VA for construction funded by these federal agencies. In addition, there may be local codes, city or county health department regulations, or building codes concerning soil treatments for existing or planned structures. Additionally, a few states have specific regulations on treating structures that have a well as a water supply.

TYPES OF WELLS. Wells are classified as either dug, bored, driven or drilled. Dug wells are hand excavated and lined with stone, brick, wood or concrete. Because these materials make poorly sealed walls and are of shallow depth, dug wells are highly susceptible to contamination. Bored, driven and drilled wells are lined with iron, steel or concrete and often sealed with concrete grout. The greater the depth of the well and the higher the quality of the seal, the less potential there is for contamination. Faulty and poorly constructed wells are the most common cause of contamination. Faults in the sealing of the well permit surface water to enter the well, usually along the pipes leading into the dwelling. This type of well is also susceptible to bacterial contamination. Drilled wells are most often the deepest wells and are the least susceptible to contamination.

PRE-TREATMENT PRECAUTIONS. Physical features of the property can contribute to accidental contamination. Inspecting the property and taking the following precautions prior to treatment will reduce the risk of accidental contaminations:

• Do not treat soil beneath structures that contain below-grade wells or cisterns within the foundation walls.

• Determine the location of the feeder line from the well to the point where it enters the structure. The feeder line is a potential pathway for fluids, such as surface run-off and termiticide emulsion. If the feeder line has not been installed so that it has a higher elevation at the well site than where it enters the foundation, re-installation should be considered. Dig a pit around and under the feeder pipe near the foundation. Apply a quantity of termiticide emulsion in the pit using low pressure (25-20 psi). If the emulsion collects in the pit, the soil cannot absorb the chemical, which means the feeder line could be a source of contamination into the well. If it appears that the soil will not readily accept the termiticide, it may be necessary to construct a polyethylene barrier between the house foundation and the well to prevent the termiticide from following the feeder pipe to the well.

• Pathways created by decaying tree roots can provide an entry point for potential contamination, as can soil composition, rock layers and geologic formations.

• Examine the slope of the property for run-off patterns. Ideally, the land should slope away from the well.

• Note the type of soil and moisture content. Soil that is frozen or saturated will accept little or no termiticide emulsion. The soil type and degree of compaction, topography and moisture level in the soil will influence the treatment method.

• Ask the owner about the type, depth and condition of the well and the distance from the house to the well head. Acceptable distances vary from 15-100 feet depending on local regulations and site conditions.

• Locate other wells that may be on the property as well as those on neighboring properties because they must also be protected from contamination.

• If the customer intends to hook up to a public water supply, delay treatment until after that process has been completed.

• Collect a pre-treatment sample of the well water and send it to the local health department to be tested for the presence of coliform bacteria and/or other pesticides. A positive reading means the well is already contaminated. Termiticide treatment is not advisable since the presence of coliform bacteria or other pesticides indicates surface run-off into the well, excessive percolation through the soil or too shallow a depth.

PROCEDURES TO CONSIDER. Consult state, federal or local authorities for information regarding the approved treatment practices for areas in close proximity to potable water supplies. If treatment must be made near outside wells and cisterns, along fieldstone or rubble walls, along faulty foundation walls or around pipes and utility lines leading down and away from the structure to a well or pond application should be made in the following manner:

• Use backflow preventers when filling the termiticide treatment tank, especially where tanks are being filled from a water system supplied by a well.

• Trench and remove soil to be treated and place it on a heavy polyethylene sheeting or similar material.

• Treat the soil at the rate of 4 gallons of emulsion per 10 cubic feet. Mix the emulsion thoroughly into the soil, taking care to keep liquid from running off the sheeting.

• Place polyethylene sheeting vertically on the side nearest the well to prevent water containing the termiticide from contaminating the water supply through service lines or soil cracks.

• After the treated soil has absorbed the liquid emulsion and dried, replace the soil in the trench.

Other treatment methods to consider (as outlined in the NPCA’s Approved Reference Procedures for Subterranean Termite Control include:

• Mechanical alterations.
• Trench and gravity-treat the soil adjacent to the foundation
• Reduce the pumping pressure of the chemical solution.
• Gravity-treat slabs of patios or porches instead of using a subslab injector or rod.
• Consider the use of wood-treating materials to treat infested wood.
• Clean up spills at once to prevent run-off into the well.
• Contamination of a well can be detected within a few hours after the occurrence. Take 24-hour post-application water samples and have them tested.

The preceding article was excerpted from "Pryfon Insecticide Well Decontamination Procures," a publication of Mobay Corp.

Sidebar: Taking Water Samples

If you suspect a contamination problem shut down the system and take water samples immediately. Mobay Corp. recommends the following steps:

1. Use new, clean brown glass bottles. The analytical process can be compromised if the containers are contaminated. Brown glass filter out ultra-violet light which causes photodegradation. These bottles can be obtained from most local pharmacies.
2. Take one sample from as near the well head as possible, and another from the cold kitchen tap. Open the cold water tap and allow it to run until the water pump has cycled twice before taking the sample. Also, include a sample of distilled water as a control. Label each sample bottle with the name of the pest control company, branch location, customer name, the product involved, and the date and sample number only, not the source. To eliminate bias on the part of the analytical lab, only the PCO should know which bottle contains the control sample. In addition, the PCO should establish his/her own record showing: Sample 1 (cold water kitchen tap), Sample 2 ( well head) and Sample 3 (distilled water control/blank).
3. Tightly cap the bottles and seal them in individualized plastic bags. Place in an ice chest to maintain cool temperatures. Do not expose the samples to excessively high temperatures. Ship the samples by overnight mail to a qualified laboratory for analysis.