Drainage

In 2004, FEMA began a new program to modernize their Flood Insurance Rate Maps (FIRMs). The results are digitally formatted maps that more accurately reflect the existing 100-year flood plain elevations. For the Brazos River in Fort Bend County (the County), the impact of these studies was significant. Changes in the riverbed caused increases in the flood levels by as much as 3 feet near Richmond, Texas. These higher water surface elevations resulted in a large amount of overbank flooding, not present on the earlier FIRM, which affected Costello’s client, the developer of River’s Edge. In order to properly analyze the flood levels in this overflow area, Costello used 2D hydraulic modeling, coupled with the existing 1D hydraulic modeling that FEMA was using. This analysis resulted in a much more detailed delineation of floodplain extents and depths, for inclusion in FEMA’s Flood Insurance Rate Maps. This project received the 2010 Engineering Excellence Gold Medal Award from the Texas Council of Engineering Companies.

As part of the Zachry Odebrecht Design Build team, our drainage staff provided a comprehensive hydrologic and hydraulic impact analysis for the construction of the Grand Parkway Segment G-B within Montgomery County, Texas. Grand Parkway is a newly constructed highway system to provide improved mobility on the fringes of the Houston area. Segment G-B is the portion of highway that runs just west of the San Jacinto River to Interstate 69 (US 59) for approximately 4.5 miles and spans two watersheds; the Cumberland Channel and White Oak Creek. As part of the analysis, Costello designed detention basins and channel improvements to mitigate increased flows and evaluated a major bridge crossing over White Oak Creek. In addition to providing the technical analysis, Costello also assisted in the final design of the drainage improvements, provided data and guidance for right-of-way acquisition, coordinated with various regulatory agencies for approval of the drainage analysis, and provided assistance during the construction phases.

Summerwood is a 1,400-acre development in northeast Harris County which borders on Lake Houston and has significant wetland areas. The developer, Newland Communities, chose to consider the wetlands an “opportunity”. It was Costello’s job to devise a master drainage plan and storm water management plan that would not only utilize the wetlands to their maximum potential but also restore and/or improve their integrity, which had been degraded in recent years.

In order to provide for hydration of the wetlands during dry periods, we assisted in negotiations with the City of Houston to provide non-potable water from their NE regional water plant for this purpose. Additionally, a channel along the south boundary of the property was designed to convey flows in excess of pre-development levels directly into Lake Houston. We worked closely with the Department of Fish & Wildlife to address the wetlands issue, and to obtain the required Section 404 Permit from the Corps of Engineers. The storm water quality and drainages master plans for this project received the 2007 Engineering Excellence Silver Medal Award from the Texas Council of Engineering Companies.