Base Bid Sites
The Contractor is to conduct stormwater drainage outfall maintenance / mechanical dredging at various locations in Bayou Texar, a Class III Florida Waterbody, as shown in plan documents by Kenneth Horne & Associates, Inc. (KHA) and Mott MacDonald Florida, LLC (MM). This work includes the removal by mechanical dredging of accumulated sediments and debris from five (5) of the nine (9) stormwater outfall locations and disposal of spoil material at two different upland disposal sites.
The base bid sites are: Bayview Park, Seville Outfall, Lloyd St., Tyler Ave., and Menendez Drive.
Additive Alternate Sites
This maintenance includes the removal by mechanical dredging of accumulated sediments and debris from four (4) of the nine (9) stormwater outfall locations and disposal of spoil material at two different upland disposal sites.
The additive alternate sites are: E. Desoto St., Stow Ave., E. 34th St., and Chipley Ave.
Specifics for Various Sites
Material dredged from the Chipley Avenue site and from between sample locations S-1 and S-2 at the Stow Avenue site are required to be disposed of at Spoil Location #2.
Material dredged from landward of sample location S-1 at the Stow Avenue, E. 34th Street, Menendez Drive, Tyler Avenue, Bayview Park, East DeSoto, Lloyd Street and Seville Drive sites may be disposed of at either designated Spoil Location.
Authorized activities are depicted on the plan exhibit sets by the two engineering companies.
Seville Drive Outfall has scour in the Bayou located at the discharge. Spoils can be redeposited to partially fill the scour and 40 tons of Class 1 or 2 Limestone rip rap will be required to eliminate future scour. Spoils will come from the Seville sediment removal.
Considerations
See General Notes on plan exhibit sets. Each outfall will be dredged by an extended reach excavator positioned on a barge. The barge will also hold roll off dumpsters to temporarily store the excavated material. During this operation incidental return water may be spilled from the excavator’s bucket or the deck of the barge into waters of the United States. To contain any turbidity generated during the removal of material, the barge and dredge area will be completely encircled by a weighted turbidity curtain that will extend to at least one foot (1.0’) above the existing bottom.
Once the dumpsters are filled with spoil material it will be moved just offshore and west of the spoil disposal cell. Once in position, the barge will be encircled by a weighted turbidity curtain before any material is off-loaded. The excavator will remove material from the barge and stockpile the material in the upland disposal site. A front-end loader or bulldozer positioned in the spoil disposal site will actively manage the spoil material limiting the height of the spoil cell.
The scour hole that will be filled with material dredged from Seville outfall will be placed using an extended reach excavator positioned on a barge. The material dredged from Seville will be stored on roll off dumpsters that will be staged on the barge. The barge will be moved to the scour hole at the Seville Outfall. The barge will use spuds to hold the barge in place. Dredge material will be taken from the dumpster and placed in the scour hole using the excavator. Then eight (8) inches of coarse sand followed by eight (8) inches of #57 stone and twenty-four (24) inches of Rip Rap (one hundred forty (140) tons) will be placed over the dredged material. This will encapsulate the material but also help to prevent future scour. The scour hole to be filled will be completely encircled by a weighted turbidity curtain that will extend to at least one foot (1.0’) above the existing bottom until the site is fully stabilized.
If work shall occur between March-August then City will retain qualified individuals to monitor the spoil disposal site for nesting shorebirds.
Hurricanes and/or adverse weather conditions
If storms are anticipated, all barges, equipment, materials, and contractor-responsible items are to be secured to prevent damage in accordance with permits and all applicable laws. In no case shall these items be unattended and unsecured when known storm threats exist. Local weather is subject to change quickly. Contractor is to be aware of weather threats.
