Lebanon resident urges city to investigate runoff and foundation damage after Goldenwood stormwater work

Dennis Mannen, who identified himself as a Lebanon resident and property owner at 25641 Ortega Drive, told the Lebanon City Council on April 28 that repeated flooding and erosion have damaged his land and threaten his house’s foundation after city stormwater work tied to the Goldenwood Stormwater and Road Improvement Project.

Mannen said the runoff now funnels from at least 18 storm drains — including an inlet at Ashley Field — onto his property, increasing velocity and eroding terrain he planned to develop. “This is runoff being deliberately routed into a system that was either under design, poorly mitigated, or never assessed for downstream consequences,” Mannen said. He added structural concerns: “As a result ... hydrostatic pressure is now compromising the structure of my home. Cracks have formed where the foundation meets the retaining wall, and the wall itself has begin to shift.”

Mannen said he sought a quiet, collaborative resolution for more than a year and submitted a written proposal on June 3, 2024, offering to expand an on-site pond into a two-acre retention area at no cost to the city to capture stormwater and relieve downstream pressure. He said no one followed up. “No 1 followed up. No 1 visited. No 1 emailed me. No 1 called,” he told the council, and he placed his correspondence and supporting photos and videos into the record.

Mannen told council members he had received an explanation from Derek Estell, civil project manager at Toth and Associates (forwarded by Public Works Director Richard Shockley) that the project enclosed flow and increased velocity but did not change total volume. Mannen challenged that explanation and requested records under the Missouri Sunshine Law. He asked the council to:

- Acknowledge the April 4, 2025 flooding as part of a recurring drainage issue linked to the Goldenwood project; - Produce all Goldenwood-related drainage plans, pre- and post-construction flow calculations and any stormwater impact studies; and - Authorize an independent engineering firm to perform a comprehensive on-site investigation at 25641 Ortega Drive.

Mannen said he has technical experience and the documentation to support his claims and repeated that his intent is to “fix” the problem, not to antagonize the city. He asked the council to enter his submitted materials into the official minutes and to respond in writing to his public records requests and proposals.

Council members acknowledged Mannen’s remarks during later comments. Councilor Matthew Maisel told Mannen the council would follow up, including meeting with Public Works Director Richard Shockley and pursuing further action. The council did not vote on any direct remedy at the meeting.

Proposed next steps Mannen requested — production of Goldenwood project documents and an independent investigation — were placed in the public record by his submission; the council did not announce a timeline for providing the requested documents during the meeting.