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System evaluations – Existing waste water systems

Overview: There are several reasons for an evaluation and several methods of conducting such an investigation. To some degree the reason for the evaluation may govern the desirable method. The system age and construction may also play into the desired method.

Reasons to evaluate:

  1. The buyer of a property usually wants to know the state of an on-site disposal system before purchase.

  2. A property owner has concerns or trouble with a system and would like a report by a professional.

Options:

  1. Full evaluation: includes opening septic tank and pump station and checking operation of both. These are checked at steady state, do not pump just before an evaluation. If recently pumped, they can still be checked, but some important signs or symptoms may be obliterated by pumping activity. The disposal area is dug up by hand provided that the location of the system can be found and that the depth and earth cover are such that hand digging are possible. Some systems are buried so deep, do difficult to locate that digging up by hand is impossible. A machine can be used for digging if desired. Any existing system design plans must be present for the evaluation. Characteristics of system use are listed requiring an interview with the occupant(s). Finally, system is load tested with a one day flow volume. Observations of how system handles this flow is documented. A full evaluation, including the check of the disposal area can be quite invasive and make a mess of the disposal area lawn, depending on the difficulty in reaching the disposal bed. System are rated: Good, Fair, Poor or Failed.

  2. Load test: Includes most of the full evaluation, but does not include unearthing of the disposal area. Instead, the load test is used as a measure of system condition. System that do not accept a days flow without an excessive backup are rated as “non-operational”, systems with no backup are rated as “operational”. Septic tank and pump station (if present) are checked, observations noted.

Results:

An evaluation is a snapshot in time. Future use of a system, among other factors, play a large part in the longevity of any system. Some systems that look like they are about to fail may last for years to come. The Owner is ultimately the judge of what an evaluation means to him/her, due to tolerance for future problems and expected future loading of system.