St. Joachim’s Sanitary Relief (St. Genevieve Ln. to Lynros Dr.)

TREKK conducted a preliminary study and designed improvements for the St. Joachim Sanitary Relief project to alleviate wet weather sanitary sewer surcharging and building backups within the Coldwater Creek watershed and service area in St. Ann, Missouri. 

The preliminary study analyzed the effectiveness of combining two parallel sanitary networks. The existing sewers consisted of two parallel systems – 10- to 12-inch and 12- to 18-inch in size – primarily located within the right of way of St. Joachim Lane.

A modeling effort showed that both sewer networks had inadequate capacity to convey 5- and 10-year level-of-service to the area. TREKK analyzed several different alignment alternatives, and ultimately determined that the Dawson Creek relief lateral sewer was the best option because several house laterals were tied into it. The recommended improvements included approximately 3,613 feet of 18-inch to 24-inch diameter sanitary pipe and appurtenances to convey the 10-year wet weather flow and lowering the flowline of the system by approximately 2.5-4 feet to incorporate the flow coming from St. Katherine Lane. 

We later provided final design and construction phase services for approximately 3,700 linear feet of 15- to 30-inch sanitary. The project abandoned the 12- to 18-inch sewer and replaced the 10- to 12-inch sewer with an upsized 18- to 30-inch sewer. Numerous service connections were reconnected to the proposed sewer.