SWG-2005-00696 - Cape Velero Homeowners Association - Port Bay - Aransas County, Texas

Public Notice          Project Plans          Attachment A-Mitigation Plan

The applicant proposes to conduct maintenance dredging of 1.97 acres of an existing boat launch basin and boat canal.  The boat launch basin and canal fronting the Cape Velero Subdivision was originally excavated in the mid-1980s.  The existing 1.97-acre canal/basin area would be dredged to a depth of -3.0 feet mean sea level (MSL) and would yield an estimated 6,356 cubic yards (CY) of dredged material.  In addition, the applicant proposes to establish a dredged-and-marked 30-foot-wide by 150-foot-long access channel into Port Bay from the existing boat canal.  The proposed channel would confine boat traffic to a single channel until reaching navigable depths in Port Bay, thus minimizing possible seagrass and bay bottom damage by boat traffic where no channel currently exists.  The proposed channel would have a 4- by 185-foot limestone breakwater (740-square-foot) installed on the southeast side to reduce wave energy and bay bottom creep, and to minimize sedimentation and reduce the frequency of future maintenance dredging requirements.  This feature would affect 0.01 acre of bay bottom.  Four 8-inch-diameter pilings would be installed at 37-foot intervals along the edge of the breakwater as markers to aid navigation.  The new 0.11-acre boat access channel would be dredged to a depth of -3.0 feet MSL.  The calculated dredge material volume would be 292 CY of material.

The dredged material would be mechanically excavated using a Wilco amphibious excavator.  The contractor unit is 16-foot-wide and 32-foot-long with two 5-foot-wide pontoons and weighs 58,000 pounds.  The drive system is hydraulic, powered by the Caterpillar 330 Excavator engine and hydraulic system, and has pyramid or flotation shoes on the drive system.  This excavator floats in -4.5 feet of water and has a 50-foot operating reach.  Dredging would start at the launch ramp basin and then proceed out the boat canal.  Initially, the dredged material would be placed within a ring of hay bales on the uplands adjacent to the boat basin for dewatering until the excavator is beyond reach of the shoreline.  A backhoe onshore would transfer the dewatered material to a dump truck that would transport the material to one of two upland disposal areas for unloading and leveling.  Silt fencing would be utilized at the upland placement areas to hold the material in place until stabilized.  When dredging beyond reach of the boat basin shoreline, and through the extent of the boat canal and proposed channel into Port Bay, the dredged materials would be placed on a set of small barges with sidewalls.  When barge loading capacity is reached, the individual barges would be pushed by a small outboard motor to the launch ramp and offloaded by backhoe into dump trucks.  The dump trucks would relay the material to the upland disposal areas for unloading and leveling.  Weighted sediment curtains would be used when working in open waters to minimize turbidity outside the work area.  After the material has been placed within the upland disposal areas and one to two weeks of drying time has occurred, a small bulldozer would spread the material evenly within the disposal area.  Based upon the anticipated dredge volume, an approximately 1-foot layer of material would be spread within each of the disposal areas.  Once settling and conditioning of the materials is achieved over several months, the disposal areas would be seeded with common bermudagrass to establish vegetative cover.  The expected time to complete dredging of the canal and associated access channel with breakwater is 22 days.

The applicant also proposes to install a 275-foot-long by 8-foot-wide (2,200-square-foot) breakwater consisting of a double row of 36-inch-diameter reef balls.  The reef balls would be installed on a staggered offset with 3 feet of separation.  The expected time to complete installation of the reef ball breakwater is 3 days.

In addition, the project would include launch ramp improvements through the addition of a 4- by-25-foot wing pier; a 4- by-60-foot walkway, and three 3- by-20-foot finger piers within the canal.

An estimated 4,585-square-foot of Widgeon grass (Ruppia maritima) would be directly impacted from the dredging and placement of the channel breakwater as currently proposed.