New Solon Springs, WI Force Main Protects Unique Watershed

Due to its unique geology, Solon Springs, Wisconsin has amazingly pure fresh water springs that well up from the ground with unaided flows of up to 3,000 gpm. The Village gained national fame 100 years ago for its bottled spring water. Today it is a unique watershed and forms the headwaters of both the St. Croix River (which flows into the Mississippi) and the Brule River (which flows to the Great Lakes).

The Solon Springs Waste Water Treatment Plant (WWTP) serves the Village of Solon Springs, Gordon Sanitary District No. 1, and the Upper St. Croix Lake Sanitary District. It is located one mile from the last lift station. Due to revised nitrogen rules for groundwater discharge, the WWTP needed to be upgraded. The Village hired Ayres Associates of Eau Claire, WI for the upgrade design. As part of the overall system review it was determined that the existing 8-inch ductile iron force main also needed attention. The force main was installed in the late '70's, with leaks and breaks occurring for the past two-plus decades.

Due to flowing sand and very high groundwater, trenchless construction was a natural solution for replacing the line. Ayres Associates looked at both pipe bursting and horizontal directional drilling (HDD) as possible solutions. The temporary bypass required for the pipe burst option ultimately lead Ayres to select HDD as the preferred installation method. Eight-inch FPVC® pipe or upsized 10-inch HDPE were bid as equal pipe material options on the project.

Pipeline Details and Project Summary
Project: Force Main
Location: Solon Springs, WI
Length: 6,250 feet
Pipe Size: 8-inch DR25 FPVC® pipe
Installation: Horizontal Directional Drilling and Open Cut
Owner: City of Solon Springs
Engineer: Ayres Associates
Contractor: McCabe Construction, Inc. / EBI (HDD)
UGSI Contact: Dan Christensen (715) 206-0518

The low-bid contractor, McCabe Construction, selected 8-inch FPVC® pipe due to overall material and installation cost savings versus upsized HDPE. Three days after the early September bid, the need for a new force main was further reinforced when the existing ductile iron force main failed again, dumping raw sewage into the Upper St. Croix River and resulting in over $100,000 in clean-up costs over the long Labor Day weekend.

Mike Stoffel of Ayres Associates commented: "Our design called for a fused force main to help protect this unique watershed. Fusible PVC® pipe worked very well for both the HDD and open-cut sections, and was surprisingly flexible. Getting a fused pipeline that uses standard DI fittings saved both the contractor and the Village money, making Fusible PVC® pipe the right solution for this project."

Pipe Layout

Pipe Fusion

HDD Clevis Connection

Drill Mud Collection

Open-Cut Install

Open-Cut Install

Rigging the Pipe into the Trench

Standard DI Fittings

In-Pit Fusion