Southfork and Walnut Ridge Sewer System
Waukee, Iowa
Veenstra & Kimm, Inc. was retained by the City of Waukee to evaluate options for wastewater collection in the Southfork and Walnut Ridge Subdivisions. The subdivisions are medium to upper scale homes situated around six manmade lakes and ponds.

Wastewater treatment in the area was provided by a mix of on-site treatment systems. The systems included septic tanks and lateral fields and on-site mechanical treatment systems with a surface water discharge.

The options evaluated by Veenstra & Kimm, Inc. included a gravity sewer and a low pressure sewer. The analysis showed that a traditional gravity sewer system was cost prohibitive due to topographic constraints. The average cost would have been approximately $35,000 per household, not including the cost of the service pipe from the house to the main.

The City of Waukee ultimately selected a low pressure sewer system. The City determined it would install and maintain the system with the property owner owning the on-site grinder pump stations. The property owner is responsible for the electricity and the City will provide the maintenance, except for the cost of parts, in the event of a failure.

Veenstra & Kimm, Inc. designed and provided general services during construction for the project. The project involved approximately 40,000 feet of 1-1/4-inch to 4-inch service and main pipe which was all directionally bored in place. A total of 100 grinder pumps were installed. Because the discharge point was 2 miles away from the subdivisions, a booster station was included to overcome the higher pipe pressure.

The Southfork and Walnut Ridge Sewer System project was funded with all local funds. Half of the cost of the project was specially assessed to the homeowners and the City of Waukee financed the other half of the project. The total project cost for the Southfork and Walnut Ridge Sewer System was approximately $1.9 million. This equates to an average cost of $19,000 per household.