After our much needed recent rains, water in the extensively landscaped ponds visible from the Clubhouse Garden Room turned clay-colored, while water in the pond by the garden plots has remained clear. And, six huge pipes now decorate the opposite bank beyond the cypress trees. What are those pipes for?
Site preparation for the DuBose Health Center expansion is nearly complete. Workers using heavy machines dug up and moved huge piles of earth. Some were hauled away. Most of the piles were shoveled, pushed, and spread around east of the building site to develop a new hillside parking area for Cedars staff and visitors. New retaining walls now hold back that big hill and other newly exposed dirt banks. The Cedars eagerly anticipates the Town of Chapel Hill’s last approval needed before the actual DuBose expansion construction can begin.
But, there are important related issues. State environmental regulations mandate that The Cedars slow any additional stormwater runoff caused by new hardscape on the DuBose construction site. During a “10-year storm”, rainwater must be held long enough to mimic the slower runoff onto adjacent property before site preparation began. The DuBose contractor started work to accomplish that in December by laying a 2-foot-high brown-block wall atop the lower pond’s dam. Next, the pond’s existing outflow drainpipe will be raised to increase the water level by just under a foot. No change in the waterspout is needed, since it floats.
Anticipated larger downhill runoff during a 10-year storm would raise the water pressure in the collection basin that drains from beneath the road into the upper pond. This could cause water to back up through storm grates on the side of the road. To avoid this, those six big pipes will be used to replace the collection basin’s existing, smaller drainpipe that leads underneath the bank into the upper pond. Their larger size also will conveniently provide additional water storage volume.
Scheduling this last step is highly weather dependent. In December, the contractor began this process by pumping out all water in the upper pond. But, then it rained and filled the pond up again before the job could be finished! So, until he can anticipate several rain-free weeks, we’ll need to ignore those six decorative pipes. Perhaps our favorite heron will find one of them an appealing alternate vantage point.