November 2016 Seawall Update

The next two rounds of monitoring will take place in December 2016 and June 2017

The monitoring is when TranSystems measures degradation and assesses the conditions of walls and areas known to have issues as well as reviewing the area for potential new issues.

Pilaster Repairs & Design Schedule:

  • Field Measurements by 12/2/16
  • 100% Plans by 1/13/17
  • Permits (in conjunction with West Hemlock) by 8/28/17 – (hopefully sooner!)

Hemlock Project

Complete followup on Hemlock field work is still pending the results of the geotechnical report.

TranSystems suspects that the cause of the flexural cracking in four of the panels and four of the pilasters on West Hemlock Street is due to one or more of the following factors:

  1. Low Panel Capacity due to insufficient steel reinforcing, incorrectly placed reinforcing and/or low concrete compressive strength.
  2. Local Soil Pressures higher than typical soil loading throughout community.
  3. Inadequate Wall Drainage behind wall resulting in added hydrostatic pressure.
  4. Wall Overload due to heavy equipment placed too close to wall.

As part of the investigation to determine the cause of the flexural cracking in the panels and pilasters, TranSystems conducted a field investigation consisting of the following measurements:

  1. Soil Borings
  2. Concrete Core Sampling for Compression Testing
  3. Radar Mapping of rebar location & depth
  4. Selected Local Demolition to confirm rebar size, depth and corrosion rate

To date the Engineers have learned:

  1. Concrete Strength – The tested concrete has a compressive strength of 5,000 psi which is greater than the assumed strength of 3,000 psi. The panel is 8″ thick which matches the as-built drawings.
  2. Rebar – The panel rebar size and spacing matches the as-built drawings. The rebar does not have any section loss. The clear cover on the face of the panels averages 3″ which is greater than the assumed cover of 2.5″. The extra 0.5″ of cover is good for durability; however, it results in a lower bending moment capacity of the wall panel due to a smaller lever arm.
  3. SoilGeotech Report in Progress. Once Geotech Recommendations are received the Engineers will analyze the wall for the recommended soil and hydrostatic loading.