Cape Henry Beach Replenishment Q&A from USACE

Here is a brief update regarding questions that were asked by our residents at the last SDCC meeting and since then.  The questions are followed by the answers received from the US Army Corps of Engineers project manager Chris Tolson.

 

Q1) Is the dredge slurry (water/sand) mixture discharge being monitored or sampled for hazardous materials? if so how is it sampled, in the pipe or in the bay? or if not sampled are you relying on the bay water testing to determine if the dredge material is causing any harm? I believe the concern stems from the discolored foam floating in the bay an on the beach near the discharge site.

A1) The maintenance dredged material and sediment for this project has been tested in the past and there is no concern for hazardous materials. This maintenance material is mainly sand with medium-large grain size. Hazardous metals and harmful organic compounds typically have a higher affinity for smaller grain size sediment (silt and fines). There is minimal fine material with this dredging project. The testing for this comes from the in-situ sediment prior to dredging, not the water or the slurry at the discharge. 

We maintain the effluent water quality standards associated with this dredging as permitted by the Virginia Department of Environmental Quality and Virginia Marine Resources Commission where we ensure that effluent water returning is below the turbidity threshold. However, this water quality standard is not for beach placement, and only required and tested for the upland placement we have at Maple St. Upland Site into the connecting waters. The testing of the maintenance material that we’ve done should not cause any concern to contribute to a decrease in water quality.

Regarding the discolored foam near the discharge site, the dredge slurry is aerated as it passes through the pipeline and flocculates into the foam at the discharge point which should dissipate in the swash zone.

 

Q2) Will orange sand fence be used as the perimeter of the 500 ft safety area? initial safety area just used sand fence poles and one line of caution tape. some neighbors were concerned that unleashed dogs may be able to run under the tape and be run over. Also thought a fence would deter people from ducking under to cut across work area.

A2) Orange fence will be established around the entire perimeter of the 500 foot working zone on the beach. This is a requirement in our specifications and if the contractor does not have this in place we will ensure they do, in addition to the beach watches. With that, we recommend that beach users take caution while in the vicinity of Cape Henry Beach. Children should be kept close and dogs should be kept under control and away from the working zone.

 

Q3) In areas were residential beach access use stairs at the dune line, will sand just be piled up over the bottom steps burying them in lieu of the steps being removed? residents were concerned that steps would be removed. And will sand be placed over pipe at private as well as public beach accesses?

A3) If necessary (within our placement prism), sand will be piled on top of existing stair structures rather than removal. 

We have a requirement that the contractor construct sand ramps over the dredge pipe at a maximum distance of 500 feet between ramps. The contractor is not required to place a sand ramp over the pipeline at every private access point. Should the Osprey Villa beach access lie exactly in the middle of two sand ramps that are at the maximum distance from the other, there should only be 250 feet of distance between their beach access and a ramp. But we will measure and make sure the contractor is following this specification with the next inspection. If the contractor is found to be non-compliant we will work to get Osprey Villa a sand ramp of closer distance than what is currently established. I imagine there is one at Jade Street public access for the contractor which is about ~150 feet from Osprey Villa.

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