Commissioners set Southbrook 3 plat conditional on drainage clarifications, ask Olson Engineering to sign off

Wagoner County commissioners on April 20 approved the final plat and a parallel 'bridal' (likely 'record') plat for Southbrook 3 with conditions tied to a drainage review by Olson Engineering. Planning and zoning staff provided a drainage review that showed a 1.09% increase in peak runoff for the 100‑year storm and noted that the construction plans did not clearly demonstrate compliance with the county’s subdivision regulations.

Casey Sanders of Planning and Zoning told the board that Olson Engineering’s review concluded the construction plans and drainage report "do not conclude that the construction plans and drainage report are in accordance with the Wagoner County subdivision regulations." Developers and county staff debated whether the review relied on a generic profile graphic rather than the full road-profile pages that show the full base and pavement sections over the storm sewer. Developers and the board said the physical construction includes roughly 10 inches of aggregate base and 5 inches of asphalt over the pipe in the roadway, which would meet the six‑inch minimum cover requirement in the subdivision regulations.

Commissioners asked the applicant to submit clearer profiles and design details showing actual cover over storm pipes. The board concluded the discrepancy stemmed from the reviewer looking only at a diagram of low and high pipe elevation rather than the road-profile sheets that document road depth and cover. Commissioner comments said the difference could be addressed before final approval, and the board directed county staff to secure a formal approval letter from Olson Engineering.

Action: the board approved the plat with the understanding that final signature would follow Olson Engineering’s review and sign‑off. Motion to approve (as conditioned) was moved and seconded; the board then amended the approval to change the outstanding review from Meshach & Associates to Olson Engineering and approved that amendment. Roll call on the amendment: Commissioner Henning — Aye; Commissioner Stamps — Aye; Commissioner Kelly — Aye. Outcome: amendment approved.

Planning staff said they had provided Olson with all submitted materials, including earlier reports and construction documents, and developers agreed to submit additional profile detail and drainage calculations for the phase in question. Commissioners emphasized they would not finalize the plat until the engineering review confirms compliance with the county subdivision regulation that requires a minimum cover of six inches over stormwater conveyance pipes.

Board members also noted that any remaining small increase in runoff could be mitigated in subsequent phases of construction and asked staff to ensure all clarifications are recorded in the planning documents before the chairman signs the plat.