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Ma-Me-O wastewater problems

Letter to the Editor from Dan Neil

Dear Editor:

Ma-Me-O Beach residents appreciate the attention the Pipestone Flyer has given to the unfortunate waste water problems resultant from installation of a low-pressure residential pipeline serving the community. Other Pigeon Lake residents also share wastewater problems and these letters add useful information to their concerns.

Shaela Dansereau’s comments on freezing and sewage leakage, heat trace systems failing and the probability of “damage and leaks throughout the collection pipe” prompted The Mieskes, the Ma-Me-O Beach Environmental Committee and John Slater to write and comment on specifics of note within this unfortunate problem. It is evident from these remarks that there is significant misunderstanding, and real confusion, about the various problems that face the ratepayers, particularly the 27 (out of 279 lots) that subscribed to the wastewater system with development costs in the millions.

John Slater —a Ma-Me-O municipal councilor – and presumably speaking for the Ma-Me-O administration — in his January 14th letter, made several statements that require comments for clarification and correction.

First as a background for the readers, the Ma-Me-O Beach Wastewater low pressure system was commissioned for use in 2018. The line had passed a thorough and fair series of pressure tests conducted at 150 psi. to assure the system was ‘water tight’. As the pipeline was buried at a shallow level a heat trace component was installed to protect waste material from freezing in the pipe during the winter seasons.

As it turned out In the winter of 2018/2019 the heat trace system failed. The lines froze. It has not been made clear how this problem was discovered, but many pits were excavated at locations above the sewer collection system. The underlying problems relate to an operational design feature:

while the system is in operation the pipes are completely full (no freeboard) to avoid air lock. Thus, a solid mass of frozen effluent developed to initiate the stress in the pipes. Once thawed the collection system was reopened, but not without altering the physical properties of the pipes.

In early September of 2019 during an installation a leak was discovered by an installer. The system was shut down for a few days. By mid September a larger leak was discovered at a different location, requiring a closure lasting several weeks. This closure prompted upset ratepayers request to have the system pressure tested by an independent third party and the procedure witnessed by a citizen familiar with those undertakings.

Unfortunately, the test conducted was not by an independent third-party expert, but by the design consultant without notification to the concerned ratepayers. Ratepayers continue to question the details reported from that test. The report from the design consultant stated that the 2019 post-freezing event pressure test was conducted at 60 pounds/sq. inch (psi) – not the original 150 psi selected for the tests conducted before the system was commissioned. The 60 psi selection reportedly selected contending that was the ‘operating pressure’ of the system.

A check of the Design Basis Memorandum for this system identifies the normal operating pressure is 80 psi and ranges to a maximum pressure of 120 psi. The Canadian Standards Association and the ASTM International Standard F2164 ‘Field leak hydrostatic testing of HDPE Pipe’ directs the proper method of testing. It is obvious that testing the pressure below the engineered specifications of the system is inadequate to prove the system has integrity. Beyond the pressure issues relating to the sewer system, subsequent further excavation sites conducted after the 2019 pressure test identified additional locations demonstrating continuing problems. These last issues were observed, photographed and one location legally tested for contamination.

The High-Density Polyethylene Pipe (HDPE) chosen for the Ma-Me-O Beach wastewater system is widely used and is a very strong, ductile material. The butt-fused joints for the pipe system can be made as strong as the pipe itself if properly constructed. In that respect, it was sound choice as a material for the pipe system. However, allowing the system to freeze while in operation will likely result in consequences to the systems integrity (by allowing external leaks causing ground contamination or internal leaks damaging insulation for example).

The pipe walls would have expanded due to the stress applied by the frozen effluent. In HDPE pipe it would be unusual to have the splitting or rupture from the expansive force and the joints if properly constructed would not split either. However, a force along the pipe would have been created. This is the ‘Poisson Effect’ that develops a tensile stress on the pipe as a result of pipe wall expansion and can cause two of three possible failure modes of HDPE pipe: (1) Stress Crack Growth, and (2) Ductile Failure Mode (associated with Creep and Creep Rupture). It is also possible for other modes of failure to have caused leaks (i.e. pipe joint workmanship for example), although the two methods described above offer would be likely causes of concern.

There is a video and many photographs of leak sites(some held by the Design Consultant). So, it shouldn’t be a surprise that contamination has already occurred in relation to the leaks already identified. The risk of human disease from these effects should be enough to direct authorities to conclude that the entire system requires a thorough investigation for structural integrity despite the attestations that there is not a problem. These technical revelations are strong evidence of expensive repairs and potentially serious health problems and they demand a full investigation of the on-going problems identified to date.

Sincerely, Dan Neil