City of Mount Pleasant Wastewater Treatment Plant Grit System

The grit removal system at the City of Mount Pleasant’s Southside wastewater treatment plant (WWTP) had been in use since the facility’s commissioning in 1989 and had reached the end of its life. Grit removal technology has advanced considerably since the original grit removal system was installed. These systems are now capable of greater removal efficiencies. Because of this, KSA was hired to remove the existing grit system and install a new one. This installation included a new grit chamber, pump and washer as well as mechanical equipment, piping and the associated appurtenances and electrical controls.

What is Grit?

Wastewater typically consists of three components: water, organic material and inorganic material. Much of the inorganic material can be categorized as grit, which consists of things like sand, gravel, egg shells, seeds and other large particles. Because of its size and ability to settle, grit can be removed from wastewater by the grit system before the wastewater is further treated biologically.

Why is Grit Removal Important?

If allowed to accumulate, grit can have a detrimental impact on the pumps, clarifiers and other mechanical equipment in a plant due to its abrasive nature. If grit is not removed by the grit system, it will settle out of the wastewater in other treatment units and cause an inability to effectively treat the organic component of the wastewater. If a significant deposition of grit occurs, the grit must be removed from downstream treatment units manually to restore treatment functionality.

Overcoming Challenges

The existing WWTP included a grit pump pit that was located approximately 15 feet below grade. The pit was a hazardous, confined space in which operators frequently worked. Instead of reusing the existing pump pit, KSA’s design team relocated the new grit pump equipment on top of the grit chamber to provide a safer environment for the plant’s operators.
 
As is KSA’s custom, we communicated effectively and resolved issues swiftly to produce a solution that performs as intended. The design team’s flexibility completely maximized the effectiveness of the dollars allocated for the project to meet the needs of the city. The project came in under budget and was completed within schedule.