Wednesday, May 22, 2013

Sediment Pollution / Dredging & Sediment Remediation

Sediment remains the number 1 pollutant of our nations waterways

I am a resident of Bend. Oregon and with great interest am watching the questions and solutions of the sediment problems of Mirror Pond .

Sediment traps, basins, buffers, and barriers will retain sediment on site. Such collection devices need regular maintenance and removal of the accumulated sediment. Sediment capture devices should not be the primary line of protection against off-site damage. Erosion prevention at the outset remains the best alternative.
                                            A dam fine idea to check first

 Stream bank erosion, digging into wetlands, and diverting or damming streams are not good rural or farming practices so before cutting loose with a digger or bulldozer, it's best to check what is allowed under the Regional Water and Soil Plan (RWSP) for Northland..

 This is distinguished from erosion of the bed of the watercourse, which is referred to as scour.

If the dam is removed,  the ensuing sediment flow will bury downstream habitats of both fish spawning grounds and wetlands habitats.

Also the effects of the shoreline devastation will  be litigious  (and may still peruse damages)  for unsuspecting victims of the flooding and sediment transport which would change the coarse of existing water channels.

Mirror Pond should work on what's called a mitigated negative declaration, a report which would identify problem areas and ways to lessen the impact of constriction. Much of the environmental concern will be from trucks spewing diesel emissions but that will be during construction.

Prior to commencing any actual dredging city officials should undertake a Sediment Characterization Study.

Sediment Profile Imager is an underwater technique for photographing the interface between the sea bed and the overlying water. The technique is used to measure or estimate biological, chemical, and physical processes occurring in the first few centimetres of sediment, pore water, and the important benthic boundary layer of water. Time lapse  imaging (tSPI) is used to examine read more.

While this is not unique as exacerbated by Contaminated Grasse River sediment to be stored at Alcoa West
I wager the potential pitfalls will be

  1. disposal of the dredged sediment
  2. where and by whom?
  3. who and how will these costs be paid ?
  4. how will this this landfill be monitored?
  5. will the EPA  be forced to declare Mirror Pond a Super Fund Site ?
  6.  Moreover monetary damages for injury to property and health and welfare of the families and their children's neighborhood are yet to be determined.



    Here are several news worthy articles I've dredged up that may be of interest.


     Mirror Pond options in the works 

    Four options and another questionnaire

    By Scott Hammers The Bulletin March 14, 2013 4:00 am  

    Members of the Mirror Pond Management Board got a preview Wednesday of the next phase i the effort to find a solution for the silt accumulating in Mirror Pond

    Read more

    Dredging Could Cost More Than $7 Million 

    ASHVILLE - Dredging Chautauqua Lake to remove sediment is a feasible solution, but could cost between $7 million and $9 million, according to EcoLogic, LLC.

    Read more 

    Usage of Engineered Sediments 

    After the 1953 and 1976 North Sea floods a flood defence plan was conceived to protect the Flemish part of the Scheldt estuary against future storm surges, called the Sigma Plan. 

    It is governed by Waterwegen en Zeekanaal NV (W&Z), a Flemish government agency, and since aims 2005 to combine flood defence with strengthening the river’s ecology through the creation of flood control areas.

    Read more


1 comment:

aparna john said...

Hi,The contract determines the pricing for the given project and makes it clear to the client what for he/she will pay, when to pay and how to pay. The conditions under which the contract can be terminated and the conditions under which the contract can be changed/amended are also described in the document. Thanks.....