J Street Drain, Ormond Beach Lagoon to Downstream of Hueneme Road Schedule I &
Contamination Removal Schedule II, CA
This project indicates the flexibility of MZT in managing a project with numerous complexities, including major site work such as dewatering, large work crews, fast-track construction scheduling, environmental considerations including noise control and biological monitoring.
This project includes the removal and replacement of a concrete lined open channel, construction of a bridge at an existing railroad crossing, and appurtenant work to increase drain capacity to a 100-year event. The existing channel was widened by and the channel bottom was lowered. The existing pipe culverts beneath the railroad were replaced with a large bridge. Over a mile of interlocking steel sheeting was installed by utilizing the silent pile hydraulic press-in method immediately adjacent to the deep excavations. Work included the by-pass of the existing live surface channel water flows and a separate, extensive groundwater dewatering and water processing/purification system. An existing reinforced-concrete trapezoidal channel was demolished, followed by excavation/export, drain and filter material, reinforcing steel and poured in place box culvert and vertical wall concrete channel.
Prior to the construction of the new bridge, the existing railroad was decommissioned and interlocking sheet piles were driven below subgrade to hold back the high water table (tidal influenced) and to protect property immediately adjacent to the excavation. Survey points were established on the sheet piles and surrounding areas for monitoring the vertical and horizontal alignment, and sampling and testing of the existing groundwater was performed to enable a water treatment system to be devised to ensure the discharged water was within the parameters set forth by the Coastal Commission.
Environmental considerations taken into account prior to construction included the erection of temporary noise control barrier in the vicinity of the local residents to minimize the noise during construction. In addition, qualified biologists performed sweeps and removed fish to allow the construction of a barrier to prevent the federally endangered Tide Water Goby from entering the work area.
During construction of the bridge, the ground water table was drawn down below the bottom of the excavation by the use of dewatering wells within the sheet piled area. This allowed the area to be prepared in accordance with the contract documents ensuring a firm and unyielding subgrade for construction. Surface water was bypassed through the area of construction using large HDPE piping.
Fast Track construction of the cast in place invert and bridge walls required over 40 employees of various trades to install reinforcement and place concrete in three weeks. Construction of the bridge deck and approach slabs included the installation of direct fixation fasteners for the new rail track which were cast into the bridge deck. Precision layout for installation of the reinforcement and the rail embedment were required to ensure the cover requirements were met. This project was given a very short timeframe to be complete before the rainy season started and was successfully completed on time.