It’s been a problem that has been with man ever since he began forming communities. That is simply, how to most efficiently transport sewage from homes to treatment facilities.
Gravity-dependent systems can’t cope with modern sewage disposal demands. Developments being forced to convert from septic tank systems to a system using central treatment plants has been a problem.
Housing developments are being set up on low-lying land. This land was considered to have marginal value in the past because sewage would have to be pumped uphill from the homes. Lakeside home sites are more and more popular. These locations are often prohibited from having septic tanks in order to preserve the quality of the water in the lake. Government parks may be located in a variety of terrains requiring all sorts of special sewage transport systems. Mobile home parks are being constructed on all types of sites which may have uneven land areas with their own particular wastewater needs.
The Solution
The answer can be found in the form of the centrifugal-type grinder pump in a low-pressure sewer line system.
The new generation of grinder pumps is superior for many reasons. They have recessed impellers, superior bearing design, corrosion protection, large throat openings, more powerful motors. The motors are available by Underwriter’s Laboratory for Class 1 Group D Explosion Proof applications. The grinder cutters are also easy to service.
A report presented by Freese and Nichols, Inc. of Austin describes an installation of the grinder pump system in Kingsland, Texas.
The engineers said that a conventional gravity sewage system would cost the Kingsland Municipal Water District about $10.4 million. However, the low pressure system using grinder pumps cost less than half of that figure or $5 million.
The engineers summed up the economic aspects of the systems as follows: “It has been well demonstrated by the increasing numbers of new projects that low-pressure sewer system offer attractive capital cost for new developments, especially those on waterfront property and or in difficult soil conditions. However, the Kingsland experience shows that in particularly difficult installation circumstances, low-pressure systems can be superior in total project cost, even for existing developments.”
Benefits
The Gulf States Utilities ran some test on the cost of having a grinder pump system. They found that in a family of four the system cost an additional just pennies a day on the electric bill. However, the main savings realized from the grinder system is due to the fact that the grinder system uses such a small diameter pipe compared to conventional systems. This greatly eases the task to laying the pipe and lessens the amount of destruction to the ground.
To further save cost several homes can be connected into one sewage pumping station. Infiltration is no problem with this system because the lines are under constant pressure. The main treatment plant doesn’t waste its time treating rainwater.
The sewage in the grinder system is also more finely ground than that in conventional systems. This makes it easier for the treatment plant to process the sewage. No collection screen are therefore needed at the plant.
Sewage Grinder Stations are attractive for cities hoping to expand their existing utility service area. Thus, attract more industry and better accommodate the expanding housing market. Grinder Pump Units will also attract more attention from individuals interested in acquiring lots to build homes on. Such systems will make sewage transportation feasible where it once wasn’t!
