View Bid - Loudoun Water

Loudoun Water May 28, 2013
4.6.1. Before delivery, Vendor shall confirm that all conditions necessary
to allow removal of spent GAC and delivery and installation of
new GAC have been met.
4.6.2. The removal of spent GAC and delivery and installation of new
GAC shall be between June 24, 2013 and August 2, 2013, over a
minimum period of four (4) weeks.
4.6.3. The Vendor shall determine the removal and installation methods,
subject to requirements specified below:
4.6.3.1. The spent GAC shall be removed by the Vendor.
4.6.3.1.1. The spent GAC should be reactivated.
GAC Vendor shall provide for removal,
transport, reactivation and storage of
spent GAC from the contactors. The
Vendor shall certify that it is the owner
and operator of a reactivation facility
capable of receiving, reactivating, and
storing of spent GAC from the B RWRF.
4.6.3.2. The new GAC shall be placed and the bed shall be
backwashed until the amount of fines leaving the
contactor are at a minimum and at equilibrium. Rate of
backwash flow shall be 15 to 22 gpm per square foot of
contactor area. The method and degree of washing
shall be as approved by Loudoun Water. The method of
placing GAC in the contactors shall be as recommended
by the GAC Manufacturer and as approved by Loudoun
Water. The Vendor shall recommend a slurry-pavement
method. The GAC shall be handled in a manner that will
not pulverize the GAC particles. Loudoun Water will
provide water for backwash of GAC.
4.6.3.3. The Vendor shall place GAC in the contractors initially
to a depth of approximately one-third (1/3) full. The
GAC shall then be backwashed to remove fines. The
contactors shall then be filled another one-third (1/3)
and again backwashed until fines are reduced to a
minimum. The contactors shall then be filled to final
level and again backwashed. Following this backwash,
the contactors shall be drained and the GAC level
measured. If the backwashed and drained GAC level is
below the contracted level/depth, the additional media
required shall be determined and transferred to the
contactors. The GAC shall be backwashed after the last
amount of media is installed necessary to provide a
finished GAC level, backwashed and drained.
4.6.3.4. If, in the opinion of Loudoun Water, the transfer
method used by the Vendor is creating excessive fines,
Granular Activated Carbon
For BRWRF 6 IFB No. 2013-011-240