Project Detail

Proposed SCR Bottom withdrawal pipe alterations at Devils Lake (Sauk Co.)

Purpose

Devil's Lake, a Discovery Lake and the gem of Wisconsin's most popular State Park, has a pump installed to both remove phosphorus to improve water quality as well as control flooding, which is a chronic problem. This project is the most cost-effective means to proactively control this flooding. It will re-construct the siphon pipe system at Devils Lake by lowering the portion of the siphon that is above the Ordinary High Water Mark (OHWM) lake level so that the pipe will fully flow as a gravity feed flow system whenever the lake level is above the OHWM. This entails digging up approximately 900 feet of the 1,350-ft long land section of the siphon pipe (total length 5,500 ft, HDPE pipe OD 20-in.) and lowering (retrenching and regarding) the highest point by about 4.4 feet. An additional butterfly flow valve will be installed to provide dual control of the pipe system for safety and operational purposes. The total cost for this re-construction is $48,000. This includes retrenching the pipe; purchasing the flow valve, associated hardware and manhole extensions; post-construction landscaping and blacktopping two park road sections; repair and stabilization of the channel walls near the upstream and railroad trestle intakes to the water pipe system used to divert clean bluff water into the lake, and miscellaneous costs including electrical work at the high point manhole. The work will be done principally by the local construction company (Heartland Utilities, Inc.) that won the original competitive bid to install the siphon system in 2002, and who returned to modify the siphon pipe and diversion pipe near shore in the fall of 2003 when lake levels were lower. A quote has been obtained for the new proposed re-construction work and the DNR-SCR region engineer (John Olson) has verified that the existing engineering drawings and pipe specifications are adequate to do the reconstruction. He also has sanctioned this project as the most cost-effective solution to proactively prevent flooding in the park.

Objective

Lowering the siphon pipe so that it can fully function as a gravity feed outflow system will allow the system to be turned on at any time and used at full flow capacity whenever water withdrawals are needed to prevent flooding in the park. The pipe re-construction work will take about a week and can commence (based on the contractors availability) once the flow valve has been ordered and delivered. Once the reconstruction work is done the pipe will be fully functional regardless of when the landscaping, blacktopping and other miscellaneous work is completed.

Outcome

This is vitally important given that severe flooding in the park is occurring regularly as a result of climate change causing a big increase in the frequency and magnitude of extreme rainfall events. It will reduce downstream flooding pressure, too, and reduce damage to infrastructure and homes. The lowered pipe will operate more efficiently as a siphon (with minimal vacuum leak) for the removal of phosphorus (P) during the fall withdrawal period. It will also prevent the frequent and expensive maintenance of the existing pump system. Shoreline erosion will be minimized, historic buildings will no longer be damaged by high water, and water quality will no longer suffer from sewage overflows. Preventing these problems are critical to Devil's Lake State Park.

Project Type

Targeted Monitoring

Project Sub Type

Watershed Project

Project ID

SCR_01_CMP10

Year Started

2009

Status

Inactive

Reports and Documents

DEVILS LAKE COMMENTS

PROPOSED BUDGET DETAILS

PROPOSED BUDGET

Activities & Recommendations

Protect Headwaters and Springs

Improve the pumping system that both removes nutrients to restore water quality and helps manage lake levels to protect shoreline, buildings, parking lots, and downstream homes and communities during floods.

Watershed

Waters

Purpose

Objective

Outcome

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