Inflow/Infiltration (I/I) Removal Program
For information on Inflow/Infiltration click on the link below:
During the fall of 2007, our staff undertook a project to locate and mark all of our system manholes in preparation for the aerial photography of our system. During this process, we found numerous system deficiencies or damage which needed attention. The most serious was within the downstream trunk sewer line running to Walcomet. The system manholes were the primary source of the leaks, however there were also leaking joints in the 36"sewer, which would need repair. This is a wetland area, so we were in contact with the County and DNR during the planning for these repairs and hired a contractor who was able to do most of the work during the winter when the ground was frozen. This project initiated our I/I removal program.
In July of 2008, Walcomet informed its customers that it would be embarking on a cooperative I/I removal program as required by their Wastewater Facilities Plan prepared in conjunction with the Treatment Plant expansion project. This plan commits Walcomet and those entities served by Walcomet to reduce the amount of clear water inflow into their systems so as to extend the life expectancy of the new plant upgrade. Flow information was presented which clearly showed that the Treatment Plant was receiving great quantities of unpolluted clear water. This costs the public money related to unnecessary volume charges and puts pressure and stress on the flow management elements of all of our systems. From the State and Federal perspective, the failure to correct these problems will greatly reduce the life expectancy of the new plant upgrade. Therefore the removal of this I/I is not an option. We have been asked to voluntarily take measures to reduce our system inflow and produce a plan for doing so. If satisfactory progress towards established I/I reduction goals are not met, then Walcomet will be forced to put us under order to comply. Associated with this could be large fines and the inability to plan and perform this work in coordination with our other responsibilities.
We have submitted the required plan to meet the Walcomet goals; however, we are also fixing problems as we find them. We have found major leaks in our collection system and they have either been repaired or repairs are planned.
With the summer 2008 heavy rains and very high ground water conditions, we have found many areas where sump pumps are directly connected to our sanitary system. All residents of the District have frequently received the following notice:
"No persons shall make connection of roof downspouts, exterior foundation drains, area drains, including sump pumps, or other sources of surface runoff or groundwater to a building sewer or building drain which is connected directly to a sanitary sewer. Delavan Lake Sanitary District employees are permitted, in accordance with their Sewer User Ordinance and Section 200.11(3) Wisconsin Statutes, to enter all properties for inspection of the premises for any violations. If any of the above are found to be connected to the sanitary sewer system, the District will require the property owner to disconnect these facilities immediately at the owner's expense."
Although this notice has been sent out on a regular basis, the enforcement of the requirements has been intermittent. In many cases, the residents with these illegal connections had no other place for the water to go. It was their attempt to protect their property. In other cases, residents were pumping standing surface water into our system at the worst possible time and for this, there is no excuse.
With the heavy rainfall and high groundwater levels experienced during the summer and fall of 2008 (and actually going back to 2007), the effects of illegal sump pump connections has risen dramatically. The Town of Delavan has been doing various storm drainage projects and it is hopeful that once these projects are complete the improved drainage will help remedy the situtation. Unfortunately, many of these areas are low and the original drainage has been blocked as property values increased.
The District must enforce our ordinance (as well as Walcomet's ordinance, DNR and EPA regulations and the Department of Commerce Plumbing Code) while also recognizing that in many cases traditional solutions will not work. We have a responsibility to our ratepayers to remove this cost of draining private property from their bills. We have been and will have many discussions to find a reasonable, workable answer to this dilemma.
Repair of forcemain connection failure
DISTRICT I/I REMOVAL PROJECTS
DISTRICT I/I REMOVAL PROJECTS
May, 2009 Pipe Joint Repair Project
During our overall system televising a number of leaking pipe joints were identified. These leaks were prioritized based on impact to the system and repair work was scheduled. The following photos provide overview information about one process that was recently used to seal joint failures from the INSIDE of the pipe.
Photo 1 shows the actual leak prior to any work being done. This image is similar to what appeared on our original televising of this portion of the system and indicates a serious joint failure. The possible causes of this type of leak are many: tree roots, material failure, ground shifting or high ground water pressure, but whatever the cause this extraneous ground water must be removed from the system. We have found that the magnitude of the leaks vary with surface and groundwater fluctuations, however, this leak seems to have remained constant since it was originally identified.
Photo 2 shows the set up for one of the joint sealing processes. Each one of these set ups will vary depending upon how far the bad joint lies from the nearest manhole or access point. In most cases our staff work with the contractors as our familiarity with the system saves time and money. Much of this work is more art than technology and success often depends upon innovation and flexibility.
Photo 1 Photo 2
Photo 3 is a lateral view of the grout injection packer which will actually be sealing the joint. This packer includes inflatable end elements, the black rubber areas, which are inflated once the packer is centered on the failed joint. These pressurized rubber elements isolate the joint from the rest of the pipe and a grout mixture is extruded from the center section to seal the joint.
Photo 4 shows the packer being centered over the joint. By the way, the photos of the inside of the pipe are taken by directly photographing the monitor in the TV truck.
Photo 3 Photo 4
Photo 5 shows the packer right after the grout injection and deflation of the rubber elements.
Photo 6 is a shot of the monitor showing the finished grout injection and sealed joint.
Photo 5 Photo 6