Far be it for me to take on the experts and consultants in sewerage system design and the impact of implementation. In a very cold forest environment. I really do not have any quality quantification of the risks, and what follows is just local opinion and not to be taken as God's truth.
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You must verify everything we say for yourself in all the read that I write. I am albeit an author of fiction trying to decide on what is credible. My blog is trying to get you to think?
I am a software engineer and computer graphics artist and not a another type of engineer.
Bob Merkley sent out his opinion and you may read it as an opinion of an engineer and not fact.
Personal Analysis of 'Low Pressure Grinder Pump' sewage collection system proposed by Lambton Shores for Zone 3
August 2010
From: Roy Merkley, 10341 Maplewood Ave. Southcott Pines
Grand Bend, Ontario N0M 1T0
After submitting my previous analysis of the Zone 3 proposed sewer project by Lambton Shores I was asked to explain specifically what I thought was involved with the 'grinder pump' design for handling our residential waste effluent. My opinion is based on my general knowledge of equipment design and in no way am I experienced in the specific application of this type of system. However basic principals must apply.
1-What is required at each individual residence?
The existing sewer pipe to your septic tank would be modified and rerouted to a new tank assembly that contains a grinder pump, motor, level switches and some sort of screening filter to prevent bad things like bottle caps, children's toys and the myriad of items that can be flushed unknowingly down the drain from jamming up the pump mechanism. A visible ground level access hatch is required on the tank for service and cleanout.
Piping is then installed from wherever the tank is located to the edge of your property for hook up to the collection system.
Shut off valves would be required on each side of this unit to isolate it for service or repair. A check valve would be required to prevent reverse flow or back up into your tank from your neighbours' systems when they operate to empty theireffluent into the collection piping network.
Power for operating the pump must come from the homeowner's power supply and would include at least a 30 amp ground fault circuit feeding a separate panel likely mounted on the outside of your house. This would contain the necessary controls for the motor including overload protection and whatever monitoring system is required to indicate a breakdown in performance. Apparently warning lights or whatever would be part of this panel assembly. Control and power wiring must run from this panel to the pump and tank assembly.
2-What is required beyond your property line?
Each individual residence connects into a network of piping that interlaces throughout all of zone 3 funneling into the sewage treatment plant. This system must be designed for maximum flow conditions along with a suitable safety factor, thus pipe sizing will generally increase the further downstream you go.
To move the effluent in larger volumes and in many cases uphill, a series of lift stations will be required to collect and pump it along the way with larger pumps.
Again control stations are required with associated valving, electrics, monitoring etc. I would also suspect that inspection ports would be required in the pipe lines at intervals for flushing and maintenance.
3-What problems can be encountered with this system?
Most pumps like the oil and water pumps in your car handle a clean consistent fluid to be pushed down the pipe under some pressure. The effluent from the drains and toilets is pretty nasty stuff to handle since you never know what has mistakenly fallen into the outflow. Also this system requires that the effluent be ground up to produce a liquid slurry that can be forced across country to the treatment facility. Thus the pump is the most vulnerable item in the system in my opinion. It is subject to wear and misuse as well as operating on an intermittent cycle and in some cases when homes are not occupied it can be months between cycles.
Electric motors although very reliable can occasionally fail and have a certain life expectancy.
The thousands of valves and fittings again should be very reliable but are a source of leakage and failure when ground shifting and forces are applied to them from unforeseen circumstances.
There is the possibility of freeze ups in the pump and tank assembly in severe winter months when systems are inoperative for extended periods of time.
A major concern is extended power outages and the possible requirements of resetting the system even on short outages.
The level control switches in the tank can be problematic and cause serious trouble.
Since the only way of emptying the tank is with the pump, there must be ahigher risk of sewage back up into the residence when clogs occur and the system fails. This has the potential for increased insurance costs.
During installation both on individual lots and throughout the entire area care must be given to interference with all of the other utility lines that are underground.
In the winter months the municipality would have to keep deep snow cover cleared from each access cover on the tanks to allow for instant service when units fail.
4-My personal conclusion.
In today's world where energy conservation and the environment seem to be so important, this system which employs so many electric motors does not get high marks. However the most negative aspect to it is the high risk of pump failures and clogging or 'jam ups' in the tank and the distribution system.
Monitoring the alarm devices and providing service throughout the entire network requires significant resources and ultimately adds to the cost to the taxpayers. No accurate figures have been provided on costs for this system but if quality components are used it will not be cheap. Bear in my mind every single component must be made of non corrosive material.
In general there seems to be no evidence of grinder pumps being successful on such a large scale anywhere. This alone should preclude it from being considered.
We would welcome anyone with a more positive stance on this equipment. Please let us know if you do not agree with the above comments or wish to add anything. I am prepared to publish all and sundry, except silly stuff.
AW Lake
Will ye no think kindly on those who would be your friends! May the sun shine with your thoughts, today, and happiness grow in your heart! May you allow yourself some peace of mind.