Charlotte, N.C. Stormwater Repairs Ensure Compliance

Charlotte N.C. | Commercial |

Overview:

Restoration was required on a property in preparation for an upcoming stormwater compliance audit, ensuring all systems were fully functional and met regulatory standards.

Problem:

In preparation for an upcoming inspection and to ensure full compliance with stormwater management regulations, AQUALIS was contacted to inspect the stormwater system on the property and perform any necessary repairs or restoration. Upon inspection, the primary concern involved a grass swale that was no longer functioning properly and needed attention before the city conducted an audit.

After reviewing site plans and previous inspection records, the AQUALIS team began by locating utility lines in and around the work area, as excavation would be required. One of the key issues identified was sediment buildup at the invert of an inlet pipe. This type of accumulation can restrict water flow and create blockages, leading to reduced flow capacity, especially during heavy rain events. If left unresolved, this can cause flooding and, over time, may result in more severe infrastructure damage such as corrosion, pipe sagging or joint failure.

Additionally, the inlet concrete flume, which is designed to guide water into the drainage system, had become obstructed by sediment buildup and was no longer functioning as intended. The structure needed to be repaired to meet original design specifications and restore optimal performance.

In addition to the swale and inlet issues, the property’s dry pond also required restoration. Over time, woody-stemmed vegetation had grown throughout the entire bottom of the pond basin. This type of overgrowth significantly reduces the pond’s stormwater storage capacity, which is critical during heavy rain events. When dry ponds cannot store and control runoff as designed, the result can be standing water, or even localized flooding, all of which pose risks to the property and can result in costly damage.

Another serious concern was a lack of a clear foot path to the control structure, which is essential for regular maintenance and inspections. Without proper access, inspection and maintenance are hindered, creating a safety hazard and compliance issues under local stormwater management standards. The structure must remain visible and accessible at all times to ensure the system functions correctly and can be serviced when needed.

Solution:

Work began at the inlet structure, where a mini excavator was used to remove accumulated sediment at the pipe invert. Additional sediment buildup at the mouth of the inlet was manually cleared using shovels, effectively restoring proper flow into the stormwater system. The area adjacent to the invert was then excavated and regraded to eliminate ruts and ensure a level surface. Riprap was installed at the pipe invert to protect against erosion caused by water entering the structure.

Next, the team excavated around the inlet concrete pipe to remove the existing riprap dissipator pad, which was set aside for reinstallation. The excavated area was then backfilled and compacted until the elevation was properly adjusted to meet design grade. This step ensures that water exits the pipe correctly and is safely slowed to prevent downstream erosion. A layer of filter fabric was placed over the area to separate soil from the riprap and improve stability. The previously set aside riprap was then reinstalled at the base of the concrete flume, with an additional ton of riprap added in order to refresh the pad.

Attention was then turned to the swale channel. Using an excavator, all sediment and vegetation were removed from the swale bottom. A skid steer was then used to grade and smooth the side slopes and swale bottom, ensuring proper elevation for positive drainage. All disturbed areas, including the basin bottom, were stabilized using a seed mix, covered with an erosion control blanket and secured with sod staples to prevent future erosion.

To address the dry pond, the team used a brush hog to remove overgrown and woody-stemmed vegetation from the entire pond basin bottom, side slopes and dam crest. Concrete flumes were swept clean to remove any accumulated sediment. Around the outlet control structure, a combination of a brush hog, chainsaws and clippers was used to clear all surrounding overgrowth. This restoration ensured clear and safe access to the control structure, prevented future damage and brought the pond system back into compliance with stormwater regulations.