Pump Station/Lift Station Package Systems

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INTRODUCTION

Sewage lift/pump stations are used to move wastewater or sewage from lower to higher elevation, particularly where the elevation of the source is not sufficient for gravity flow and/or when the use of gravity conveyance will result in excessive excavation and higher construction costs.

Sewage lift/pump stations may be used as a matter of economics or to overcome inadequate hydraulic head when it is obvious that no other solution is practical. For instance, it may be more economical to utilize a sewage pump station to pump or lift the sewage over a ridge and let it flow by gravity to a sewage treatment plant, or to elevate sewage to pass through a sewage treatment system by gravity.

Often called lift stations, units are commonly built as a factory assembled package system. Key elements of lift/pump stations include a wastewater treatment receiving well (wet-well), equipped with lift pumps and piping with valves, a junction box, and an equipment control panel with alarm system.

The submersible type lift/pump station can be utilized on low flow, low head type installations. Two types of pumps are available for this application, grinder pumps and solids handling pumps.

A properly designed wet well is essential for efficient and trouble-free operation of the lift/pump station. The purpose of a wet well is to provide a means of allowing automatic operation of the lift station with a simple control. Use of the wet well for any other purpose, such as a storage reservoir for sewage, is not recommended. The wet well should be as small as possible in order to minimize detention time of the sewage. Should the wastewater remain too long in the wet well, septic action may occur. Although, the wet well should be large enough so excessive starting and stopping of the pump will not take place.

Advantages of submersible lift/pump stations are that they typically cost less than dry-well stations and operate without frequent pump maintenance. Submersible lift/pump stations do not usually include large above ground structures and tend to blend in with their surrounding environment.

For the most part, an engineer can anticipate a life expectancy of 15 - 20 years or more from steel lift stations. This is more than adequate in cost cases, since the anticipated flow rates are usually designed for only ten years expansion. Steel lift stations are coated with a high solids epoxy paint system and further protected by anodes to deter cathodic action.

When a concrete structure (not provided by PCS) is desired, PCS can provide the equipment package to be installed in the concrete structure in the field by the installing contractor.