Lake Flood Protection

 

(The following paragraph is an excerpt from the Lakes & Grounds Committee report printed in the August 2006 Greystone Village Voice newsletter)

 

The Lakes & Grounds Committee is presently engaged in the evaluation of our flood control system, which includes our three lakes and their associated dams and connecting streams. We were hit pretty hard by the remnants of tropical storm Alberto, which dropped more than seven inches of rain in very few hours.  Many of our streams were flooded and the dam at Winchester Lake has undergone some severe damage to its spillway. The board called a special meeting in June to deal with these problems. At that meeting, we appropriated funds to fix the spillway, which, if left in its present condition, could lead to dam failure. These repairs will be undertaken by the end of July and are the first phase in our evaluation of the system and its long-term health.

 

Flood Protection Status Updates, 2006

Tuesday, October 23, 3:00pm
A special meeting was held with the contractor to discuss the reparation work performed to date. Attendees met on top of the spillway.

Saturday, September 2
The Winchester Lake siphoning was completed. Repairs to the spillway will begin soon; the date will be posted here as soon as we know what it is.

Friday, September 1
The Winchester Lake siphoning started and continues this morning. While this is not a long-term solution, it has helped prevent flooding from our recent rains.

Dan Brubaker, City Project Manager and Stormwater Engineeer for the City of Raleigh, is negotiating a contract with an engineering consultant to look at the spillway and house flooding and water quality issues on Greystone Lake. Early in the process, they plan to hold a meeting with the neighborhood to gather their input. Dan will provide Nancy McFarlane, our HOA Board President, with additional details and a schedule once they complete the negotiations for the design contract. That information will be posted on this web site.

Wednesday, August 30
Our Charleston Management representative, Matoka Snuggs, met with Guins Excavating Service today to set the siphon for Winchester Lake. We will siphon water off of the lake to protect adjacent properties from flooding. At that time, Guins will also perform a site inspection of the Winchester spillway. We expect an estimate from that service right away, and we expect to start the repairs as soon as we receive that estimate.

With regards to the entire lake system, we have received one bid from an engineering firm and we are currently seeking two more bids from other engineering groups. We hope, with the help of a qualified engineering firm, to develop a finite plan for the care, development and maintenance of the lake system in Greystone.

 

Lake System Drain Valves and Flood Control

Under the guidance of Foster Lake & Pond Management, Inc., the Greystone HOA Board Members have learned that lake system drain valves are typically not opened for flood control. The reasons for this were presented to us by the lake management experts at Foster:
  • Our lakes and ponds were not designed or intended to have the valve opened for flood control. If flooding around the lake is a problem, we need to 1) Install a larger primary drain; 2) Add an emergency spillway; or 3) Enlarge the existing spillway.

  • The drain valve is usually the most fragile component of any lake. Damage repair can be very expensive and likely requires complete lake draining.

  • If a stick or piece of debris is lodged in the valve while it is open, it may not close. Then the lake may drain completely and kill all of the fish and other fauna and flora.

  • An open drain valve can be very dangerous. If a person or animal gets sucked into or onto an open drain, death is likely.

  • The lake may take a very long time to refill and a drained lake is not attractive. Weeds cover the bare sides of partially drained lakes.

  • Weather forecasts are not reliable enough to prepare for coming storms, and we may not be able to drain the lake sufficiently to have enough flood water storage by the time the flood water arrives. Most lakes require three to five days with the valve open to lower the lake enough to help. Forecasts are not reliable enough to plan that far in advance.

  • Rainfall predictions are not accurate enough and are too variable from location to location. If heavy rain is predicted and doesn't occur, the lake water level may remain low for months.

  • Water drained through a lake valve is usually deep water that is drained late in the summer, during hurricane season. It has a bad odor that offends property owners below the dam.

  • Downstream property owners perceive that the open valve makes their flooding worse.

There are additional issues regarding the design and location of the drain valve that make it difficult to reach and unlock the valve, particularly on short notice. Therefore, our flood control experts have adopted a policy of strongly discouraging the practice of opening the valve for flood control. If a client (such as Greystone) insists that the valve be opened, the lake management company requires the client's signature on an agreement that identifies their reasons for discouraging the procedure, limits their responsibility or liability for damage and explains why their significantly higher fee for the activity is justified. All of this may place the Greystone homeowners at serious risk and great expense.