Lake Lure Sewer System Replacement and Renovation Overview and Update

The Town of Lake Lure is progressing with the sewer system and wastewater treatment plant replacement and renovation project.  The following document provides a detailed overview of the current plans with updates in January 2023 at the end of the report.

A. Background: Currently, Lake Lure’s 1927 gravity fed subaqueous (under lake) sewer system (SASS) collects and conveys sewage within submerged pipes. This is a one-of-a-kind sewer system; the only one of its kind in NC.  In fact, there are only a handful of systems in the country.  

B. Problem: The SASS conveys wastewater to a pump station behind the Dam which pumps the wastewater to the treatment plant.  Both the pump station and the treatment plant are plagued with significant lake water infiltration and outdated equipment.  The lake water infiltration puts the pump station at risk of a sewer spill.  This forces the wastewater treatment plant to use a chemical process which would otherwise be unnecessary.  Additionally, the cast iron pipes that make up the SASS are approaching 100 years old and have reached their service life.   

C.  Solution: A phased rehabilitation and eventual system replacement approach is underway to maintain sewage service while improving system performance.  The design and implementation of the new state-of-the-art engineering solution is challenging because it remains in the lake.  Specifically, the new collection system will be installed in the backshore, which is the land exposed during lake drawdown periods. Construction on Phase 1 of this multi-phase approach is slated to begin in 2023.

D.  Oversight and Collaboration: The Town is working closely with the various NC Department of Environmental Quality Divisions, including the Division of Water Resources, Division of Water Infrastructure, and has hired LaBella Associates, a firm specializing in wastewater infrastructure, to implement a sequential engineering solution that leverages modern sewage collection and treatment technology.  In February 2020, LaBella developed and analyzed twelve alternative engineering solutions that have been reviewed before a final option was selected. 

E. Community Engagement: The Lake Lure Town Council held three Community Forums on 7/28/20 to share the background and these plans with citizens. If you missed these forums you may review the following information: 

• You may view a recording of the meeting.
• You may download the presentation materials and attendee booklets. 
• You may review the Frequently Asked Questions and Answers.

F.  Benefits of the Plan: The Lake Lure Town Council selected a solution that utilizes the backshore area to install a gravity lift system that uses a combination of gravity sewer lines and pumping manholes to provide sewer access around the perimeter of the lake.  Lake Lure’s new eco-friendly sewer system will minimize property disruption while allowing property owners to maintain and enhance property values by providing a sound new system that protects the environment.  The proposed system will eliminate system issues and prevent failures that could occur if we did not take action.  This system has the lowest environmental, economic, and social costs of all the alternatives considered. 

The perimeter system will be installed around the lake perimeter, and will utilize high performance and long life components that include:

• High-density polyethylene (HDPE) sewer lines
• HDPE manholes with concrete encasement
• HDPE pump stations with concrete encasement HDPE laterals

This renovation is a long term solution which will provide service to areas not easily served currently.  It will simplify the connection effort, providing access to a gravity sewer for each property on the lake.  The Town will be able to carry out operations and maintain the system year-round. Your renovation/rebuild options will significantly increase with the new system in place and property owners will have the option of making additions once the project is complete. 

G. Wastewater Treatment Plant: Renovations to the wastewater treatment plant will be included in Phase 1 that will improve its operation until the eventual rehabilitation and conversion to a biological process capable of meeting the current water quality standards.

H. Manholes: The plan included the rehabilitation of the existing manholes which was completed during the 2021-2022 lake drawdown. This rehabilitation reduced lake infiltration, extended the life of the existing manholes, improved the wastewater treatment process, and allow for new connections to the system.  Phase 1 will begin near the Dam and will continue along the northern and southern shoreline as illustrated in the map on Attachment C.

I. Sewer Access Value/Reservoir Drain: The long-term solutions include a sewer access valve.  The sewer access valve or reservoir drain will give much needed capabilities and will allow for the ability to lower the lake below the spill way.  The new sewer access valve/reservoir drain is an important component of Phase 1 that will greatly aid in the construction of the new collection system, and is also an important component of the emergency response plan in the event of a catastrophic collection system or an immanent dam failure. The engineering design for the sewer access valve/reservoir drain has been completed and we are in the process of ordering the valve/drain.

J. 2023-2024 Lake Drawdown: In July 2022, Town Council will finalized plans for the 2022-2023 Lake Drawdown period to support this important project. The lake will begin to be lowered on 1/1/23 to support several important infrastructure projects.

It is anticipated that the lake will begin refilling on 3/31/23. The rate of refilling the lake is dependent upon weather conditions but information will be posted here regarding weekly lake levels. Lake levels will vary during the drawdown between 5 feet below full-pond and 12 feet below full-pond, depending on the work requirements of contractors. 

A list of projects to be completed during the lake drawdown is listed below: 

• Beginning of Phase One of the sewer system replacement project. This will include boring pipe sleeves on properties in the Sunset Cove area.    
• Lake dredging with excavators
• Seawall repair/replacement
• Penstock inspection and warrantee repairs
• Work on deep water access ramp near the dam

NOTE: Contractors working on seawall repairs/replacement must be out of the lake by 3/15/23.  

The sewer access valve will be installed as soon as it arrives and this will allow the lake will be lowered approximately 20’ for the construction period which has yet to be scheduled. We will communicate the next drawdown period as soon as these plans are finalized.