Environmental reclamations

                     


General

In the environmental reclamations it is of pre-eminent importance to have the possibility of selective dredging of the top layers of contaminated sediments, that very often, have a thickness of only few centimetres,thus to avoid the inconvenience of sending to the treatment plants and/or to special disposal areas also the lower layers of non contaminated sediments.

The traditional dredging systems ( cutter/auger suction dredges, bucket/grab dredges, trailing suction hoppers ) do not have the capability of selective dredging of small thickness of sediments.
Indeed, the suction pipe's head plus the part of the cutter below the suction pipe must be maintained sunken into the sediment, to avoid pumping clear water, and it represents the minimum thickness that can be dredged.

 

 

The Pneuma Pump, equipped with purpose at low advancement speed ( 1-5 m./min. ) and suspended by the lifting wire to the scheduled depth, guarantees the selective dredging of the polluted sediments only, with an high concentration of solid in the dredged mixture and without any secondary pollution.

Therefore considering that the cost per cubic meter of sediments treatment (incineration, chemical treatment, etc.) and/or the cost of purpose built disposal areas are much higher than the cost of the dredging, the utilisation of a system which allows a selective dredging represents an unquestionable advantage in terms of cost saving (see typical example on next page ).

 

Example

Surface to be dredged

100,000

sq.m.

Top contaminated layer thickness

0.30

M.

Total quantity of top contaminated sediments

30,000

cu.m.

Dredging estimated cost

10.0

$/cu.m.

Dredging total cost

300,000

$

Treatment average cost

125.0

$/cu.m.

Total treatment cost ( for 30,000 cu.m.)

3,750,000

$

Additional quantity of material to be treated for each cm. ( 0.01 m. ) of dredged material exceeding the required 0.30 m. thick. in the total area

1,000.0

cu.m.

Additional cost for dredging the additional 1,000.0 cu.m.

10,000.0

$

Additional cost for the treatment of the additional 1,000 cu.m.

125,000

$

Considering that with the standard Cutter Suction Dredges the minimum dredged thickness is approximately not less than 1.00 m. and with the small new dredges with horizontal auger the minimum dredged thickness is approximately 0.50 m., the addition cost for the treatment of the exceeding dredged sediment will be respectively of
$ 8,750,000 and $ 2,500,000.


For further information please do not hesitate to contact our senior partner,
Dr. Giovanni Faldi, c/o:

Pneuma s.r.l. via di Varlungo, 59/a 50136 - Firenze - Italy
Phone +39.55.69043 - 6503221
Fax +39.55.6503989
e-mail: info@pneuma.it