24/06/2022
Here's the letter from the city manager to council about the Long Mill Dam. This was the impetus for the discussion in Tuesday's night work session.
Meeting Date: 06/21/2022
Subject: Long Mill Dam
From: Ken F. Larking
COUNCIL ACTION
Work Session: 06/21/2022
SUMMARY
Later this year, the City plans to begin construction of the River Front Park. The Park will be near the Long Mill Dam and have features that bring people close to the river. For the safety of the public, staff is recommending that the Long Mill Dam be removed. The dam no longer serves any useful purpose. There is concern that, with more people in the area visiting the future park, the renovated White Mill Bridge, River Walk Trail extension, and the redeveloped White Mill, there will be more potential for people to be harmed by the existence of the dam. The dam also puts first responders at greater risk, should they be called upon to rescue people in distress.
In addition to the public safety benefit, there are permitting and environmental benefits associated with removal of the dam. In order to build some planned features of the future park, there are state and federal permits that are necessary. Including removal of the dam in these permit applications, will make it more likely for the planned features like the overlook to be permitted, because the dam's removal will reduce the flood plain on adjacent properties. Also, according to the Nature Conservancy, "removing obsolete or derelict dams gives rivers more access to natural features—like floodplains, wetlands, side channels and marshes—which can help: improve water quality; support healthier, native plant communities; enhance fish and wildlife habitat; create or enhance recreational opportunities; recharge important aquifers; and, in cases, reduce flood risks for communities." The Department of Game and Inland Fisheries supports removal of the dam.
BACKGROUND
In 2012, the Long Mill Dam was deeded to the City of Danville. The dam was constructed around 1894 by Dan River Power & Manufacturing Company. The dam is approximately 5' tall, 1,150 feet in length and is considered a low head dam.
The dam is characterized as a low-head dam. According to the American Society of Civil Engineers (ASCE), "A low head dam is a manufactured structure, built in a river or stream channel, extending fully across the banks. A low head dam is designed and built such that water flows continuously over the crest from bank to bank. If water levels rise downstream, a submerged hydraulic jump can form which produces an upstream directed current that traps any recreationist who might go over the dam." These dams are sometimes referred to as "drowning machines" because of the hazard they pose to recreational users of rivers.
In April 2010, at what was the Brantley Dam, a five-year-old boy died after falling out of the boat he was in and was caught up in the circulating current that was caused by the dam. The City removed that dam in 2011. In August 2020, one adult was injured, and another adult died after their canoe went over the Long Mill Dam and overturned. Last year, five people died in Eden after the tubes they were in went over a low-head dam on the Dan River near Eden, North Carolina. Earlier this month, 12 people were involved in an accident on the James River when they went over a dam. Two of those people died.
Since the dam no longer provides any useful purpose, is a hazard to the public and first responders, and will aid in the permitting process for construction of the River Front Park, staff is recommending that the dam be demolished and the Dan River be restored to its natural state. After extensive investigation of the river bed in that area, we anticipate that this section of the River will look similar to the section downstream of the dam with large rocky features showing above the waterline when the river is at its natural level.
The Union Street Dam, which is further up stream, is not under consideration for removal. That dam will be necessary in order to control the volume of water into the planned white water feature, which will be located where the canal is on the south side of the White Mill.
RECOMMENDATION
Staff recommends that the City Council adopt a resolution authorizing removal of the Long Mill Dam located on the Dan River adjacent to the YMCA.
