Oxbow Valley Storage Sites A&C
The work includes the mass excavation of the Riverside Oxbow- Sites A and C for the purposes of developing valley storage for the Fort Worth Central City project. In addition to the mass excavation the project includes the removal and replacement of existing trails, aquatic mitigation features, a prefabricated maintenance bridge, installation of a wet well and irrigation pump system, temporary river crossing, two weir structures, storm drainage structures and facilities, site restoration using a variety of seed mixes and incidental related work. Site A consists of an approximately 140 acre site which requires an estimated 1,325,000 CY of excavation with 50,000 CY maintained on Site A as fill and the remaining 1,275,000 CY exported to the Site L disposal site. The Contractor has the option to dispose of a portion of this material at a Contractor supplied disposal site as allowed by the contract specifications. A temporary site entrance will be constructed and maintained for ingress and egress of construction equipment and hauling. Site C consists of an approximately 15 acre site which requires an estimated 210,000 CY of excavation all of which is exported to the Site L disposal site or alternative site as allowed by the contract specifications. A temporary river crossing will be required to remove the material from Site C to Site A for transport off-site. Site L consists of an approximately 55 acre site which is capable of handling all of the exported materials from Sites A and C. Soils to be exported off of Sites A and C are required to be tested prior to disposal at Site L by TRWD. TRWD has completed the first round of testing for the first (6-8 feet) of excavation for sites A&C and have found no contaminates above the acceptable levels and the first layer of soils are cleared/acceptable to be disposed of at Site L. The Contractor has the ability to export a portion of the material to an approved alternative site as allowed by the contract specifications if desired. The maintenance bridge on Site A is proposed as a prefabricated steel truss bridge with faux trusses for aesthetic purposes. The bridge must be capable of a HS-20 loading criteria and is approximately 64ft long and 20ft clear width between the guardrails. The bridge will be placed on a concrete abutment supported on drilled shafts embedded in the underlying bedrock. Two weir structures will be constructed. The first is located on the front of the existing Beach Street low water dam and is approximately 250ft long. The weir will constructed with steel reinforced cast-in-place (CIP) concrete. The second weir is located on the reconstructed Sycamore Creek channel and immediately downstream of the new maintenance bridge. The Sycamore Creek weir is also a steel reinforced CIP concrete structure however it includes galvanized steel channel and center post to allow for the installation of wood stop logs for invert control. The reconstructed Sycamore Creek channel will serve as an aquatic mitigation component to the project and thereby includes a series of pool and riffles complexes to create habitat through the use of different channel bed materials. The pools will include woody debris. Along the channel is a pre-cast modular retaining wall and sections of vegetated revetments in addition to the erosion control blankets and seeding. Site A includes construction of a permanent irrigation pump station that will pull river water from the Trinity River for use on irrigating the site in the future. The pump station may be used by the Contractor during construction for irrigation and other water needs. The pump station will require the installation of three below grade structures, electrical power, control panel, and other appurtenances.