The remnants of Tropical Storm Chantal damaged police cars and garbage trucks in Carrboro along Morgan Creek and destroyed structures in the Morgan and Bolin Creek flood zones in Chapel Hill. Stores in Eastgate experienced 5 feet of flooding. Bolin Creek in Carolina Forest often floods, but this time the floodwaters were so strong that they washed away soil above the buried sewers and lifted entire sections of the Chapel Hill paved greenway, causing millions of dollars of damage.
Bolin Creek in the OWASA corridor in Carrboro experienced close to 12 feet of flooding based on the debris snagged on trees along the easement. The storm washed out multiple sections of the buffer, causing severe erosion.
OWASA undertakes repairs in the Bolin Creek Natural Area, composed of UNC’s Carolina Forest, the PH Craig Tract, and the Adams Preserve.
Bill Rosa, a member of the OWASA staff, supervised a contractor team working on repairs along the part of Bolin Creek that runs under Homestead Road south to the bridge on Estes Extension. Because OWASA has an easement along this riparian corridor from the property owners, they are authorized to perform these repairs. FEMA funds are expected to reimburse OWASA for the extensive work.
Bill contacted community members and the Friends of Bolin Creek leadership to inform them of OWASA’s plans, which included bringing in heavy equipment and placing tons of white rock (Surgestone) to fill the fissures where sewer pipes cross the trail. The initial plan was to cover the white rock with Chapel Hill gravel, a quarried decomposed granite native to the area.
Briefing with OWASA. As it became clear that the heavy equipment and piles of large white stones in the easement were altering the forest recreational experience, Friends of Bolin Creek (FOBC) asked Mr. Rosa to give us an on-site briefing. Bill also invited other OWASA team members, including the head of the Capital Improvements Program (CIP), who will oversee the planned sewer replacement project a few years from now.
On October 6th, Friends of Bolin Creek members gathered at the UNC bridge over Bolin Creek to discuss OWASA’s plan to repair the extensive storm damage. Bill Rosa led the briefing along with five OWASA team members, including the Capital Improvement Program (CIP) manager, who will oversee the planned sewer replacement project a few years from now. Heather Holley, Stormwater engineer with the Town of Carrboro, and Janet Clarke, UNC Stormwater engineer, joined the briefing.
Photo courtesy of Cliff Haac.
Repair materials. Bill gave an update on the extent of the damage and outlined the repair plan, which involved adding 2 inches of “Chapel Hill gravel” after the rock base was in place. After Clarke and Holley, engineers from UNC and Carrboro explained that the Chapel Hill gravel would float and wash away into the creek during storms, OWASA agreed that the material was unsuitable for the riparian zone. Clarke and Holley recommended using ABC Aggregate instead – a material more likely to create a stable, semi-permeable surface suitable for walking and biking.
Their advice was adopted, resulting in the surface seen below. Walkers and bicyclists are finding the new surface very comfortable, and the potholes and large rocks are gone from the trail bed. When walking south from the High School, this excellent surface extends to the power easement intersection with the trail. Before the decision to use the aggregate was made, OWASA had spread Chapel Hill gravel along the trail southward. It will be interesting to see if it holds up in the next storm. If not, more repairs will be needed.
The silver lining for Bolin Creek is that OWASA’s extensive repairs have created a usable, recreational trail along much of its 2-mile length. The damaging storm may well save the Town of Carrboro millions of dollars in design and construction costs for a paved trail, when we already have a usable, bike-friendly trail that everyone likes.
While we don’t have a final report about how the new trail will hold up in the next flood, for now, Carrboro has a 2-mile, somewhat permeable path suitable for biking and walking. This highly usable, improved trail is a gift to the walkers, runners, and bicyclists who love Bolin Creek and the forest.
Greening the riparian buffer. Friends of Bolin Creek will join with our partners and experts to identify creek mitigation projects to repair eroded areas in the creek banks, and to engage in planting projects that will re-green the buffer zone, strengthen root systems, and create a self-sustaining creekside ecosystem better able to withstand future storms. If you want to join our effort, contact info@bolincreek.org.