Overview
In 2014, Timmons Group was awarded an annual services contract with the City of Poquoson for engineering consultant services. To date, tasks assigned under this contract have included drainage and water quality project design. However, the scope of the contract encompasses stormwater, structural engineering, transportation, and sanitary sewer consulting services. Projects have included:
Little Florida Road Drainage Improvements
The City of Poquoson planned to install storm pipes to replace the ditches on the north side of Little Florida Road from Far Street to Cedar Road in an effort to improve the safety of the corridor for motorists. Timmons Group developed construction documents for the improvements. Due to budget constraints, the design was optimized to maximize storm system capacity while avoiding public utility conflicts. The design was also developed to allow the City the flexibility to phase construction of the project by limiting proposed pipe depth and providing the contractor with detail to tie the improvements into the existing upstream condition. The project was constructed in 2016.
Oxford Run Adjacent Water Quality Retrofits
The City of Poquoson identified an opportunity to improve the overall water quality of the watershed draining to Oxford Run ditch by installing new retrofit best management practices (BMPs) on City-owned parcels adjacent to and draining to Oxford Run ditch. The ditch is located between Big Woods and City Hall and drains approximately 500 acres, including a portion of York County. The Oxford Run ditch watershed contains many older developed areas that were designed to lower drainage conveyance standards. Flooding is a major issue in some upstream portions of the watershed. In addition to water quality treatment, the retrofit projects also offer a secondary flood mitigation benefit. Siting, sizing, and capital cost-benefit calculations were developed for the preferred BMPs—a wet pond and a constructed wetland—designed to remove 11.5 pounds per year of phosphorus and provide flood storage.
Timmons Group, on behalf of the City, requested and received authorization for grant funding through the Virginia DEQ SLAF program. Design and environmental permitting were completed and the project was advertised in the Fall of 2015. Construction was completed in mid-2016.
