Engineer tells Sumner County property owners to inspect, maintain stormwater systems to reduce pollution

Van Holdom, a licensed civil engineer and owner of Evergreen Infrastructure, told attendees at a Cumberland River Compact presentation that private property owners and associations are generally responsible for long-term inspection and maintenance of stormwater infrastructure.

"The burden is definitely on the property owner," Holdom said, describing long-term maintenance agreements that are recorded as deed restrictions and require annual reporting and periodic professional inspections.

Holdom told the audience that nonpoint source pollution — "basically everything that you see" running off roofs, parking lots and golf courses — carries sediment, nutrients and bacteria into lakes and rivers, feeding algae blooms and reducing dissolved oxygen. He said sediment is the largest pollutant in Tennessee waterways and that sediment binds and transports metals, phosphorus, nitrogen, viruses and bacteria into receiving waters.

Holdom reviewed common types of post-construction stormwater controls and their maintenance needs, including dry detention (dry) ponds, wet retention ponds, bioretention (rain gardens), permeable pavers, underground detention chambers, hydrodynamic separators and proprietary cartridge filters. He said expectations and inspection schedules differ by device: for example, bioretention systems require regular mulch and plant maintenance to protect the filtration media, while many proprietary filters collect predictable quantities of sediment and debris and need cartridge servicing.

Holdom cited several practical recommendations for property managers and HOAs: keep grass in pond areas no shorter than about 6 inches; remove accumulated sediment promptly; replace shredded hardwood mulch on bioretention cells to protect the media; avoid use of granular pre-emergent herbicides and unlicensed pesticide application in aquatic sites; and schedule regular inspections and maintenance contracts to avoid violations. He recommended quarterly maintenance for many bioretention cells until native plants are established and then annual visits once systems are functioning as intended.

Holdom said documentation is critical. Original construction plans and as-built surveys can show design volumes and features; he noted some jurisdictions are beginning to require post-construction as-built surveys to verify pond storage volumes. He gave Nashville as an example where a GIS parcel viewer includes a layer identifying stormwater features and estimated that Metro Nashville has about 8,000 properties with stormwater features and about 100 new features per month.

Holdom described common failure modes: ponds filled by decades of sediment lose design volume and flood-control function; bioretention media can clog if mulch and vegetation are not maintained; permeable pavement can lose infiltration capacity when sediment becomes embedded in the stone below pavers; and proprietary vaults and cartridges can have a small layer of sediment on top of cartridges that indicates slowed flow and early failure. He demonstrated small, lower-cost repairs as alternatives to expensive replacements, saying an epoxy injection to stop leakage in an outlet pipe cost roughly $10,000 compared with an estimated liner replacement of about $120,000 at one site.

Holdom also explained services his firm offers to address violations and long-term care. He described an "EverCare Standard" inspection and reporting plan (six-month inspections and reports for regulators) and an "EverCare Complete" plan that combines inspections with the maintenance work. He said the company responds to violation letters, prepares plans to return systems to compliance, and then places systems on a scheduled maintenance contract to reduce risk of repeat violations.

There was no formal action taken at the event; Holdom provided education and described commercial services and field examples. During a short question period, attendees discussed operational details such as regenerative vacuum sweepers for porous pavements and cartridge handling for filters.

No ordinances, motions or votes were recorded during the presentation.

Holdom closed by noting that maintenance and documentation reduce long-term costs and protect downstream water quality. "If there's water in the vault and it hadn't rained in the last two or three days, it's not working," he said, urging timely inspection and follow-up for problem sites.