Letter to The Pocahontas Times from Jim Smith

Dear Editor:

Having worked for 21 years for a large County Water and Sewer System, I must comment in regard to Mr. Holmes, who from his letter has no knowledge of how a sewer system is designed or works. Additionally, it would probably be good for everyone who may ever connect to a public sewer system to at least understand the basics of how a system works.

Especially those people who are in a decision making position.

To begin with there are strict engineering standards covering the design and installation of water and sewer mains. Most states use the standards developed by the State Standard, International Building Code, American Water Works Association or have developed their own standards based on local conditions and sound engineering practices.

Sewer mains are to buried a minimum of 24-inches. Mains made of PVC or any other poly material must be buried as the pipe will deteriorate due to exposure to weather and ultraviolet light. Properly installed and maintained sewer lines will at some time eventually leak, but having them exposed is not the correct method.

The steep slope of the pipe actually causes stoppages, sewer mains are designed to carry a certain amount of flow at a certain velocity based on the pipe size. The pipe should be designed to maintain a velocity that keeps the solids suspended in the liquids. When you have a pipe at a slope of 15% or greater the liquids will separate from the solids and the solids stick to the bottom of the pipe creating a dam which in time enlarges by collecting additional solids until you have a complete blockage.

Manholes are used for inspection, access, to change directions and to maintain design grades, not to trap foreign objects. On steep slopes the manholes are used to eliminate severe slopes by having the main enter at high point in the manhole and exit at the bottom elevation. This is called a drop manhole and is quite common in steep areas. The recommendation by the PSD to replace the sewer system is correct because it is apparent from the violations issued and the construction of the system, it was not done to any engineering standard and probably was not inspected by the appropriate state permitting agency.

It is important to have strict guidelines and regulations pertaining to the design and installation of water and sewer systems and to have a qualified inspector on site during the construction. It is also important to understand that an improperly installed system can and will cause sever ecological damage in the event of a sewer spill or overflow, not to mention the possible damage to a residence in the event of a backup into a home.

I have seen instances in which a small overflow of less than 5,000 gallons has totally killed all living organic life in a small stream for a distance of over two miles and even after cleaning the stream it took over three years for it to recover to the point it could sustain minimal aquatic life. Now imagine a spill of 100,000 gallons into a local stream of the Elk River in the middle of the summer at low water level.

Jim Smith
Marietta, GA