Document Page: First | Prev | Next | All | Image | This Release | Search
File: 011696_129_15_027.txt
a gravity by-pass for diverting the flow directly to the sea
or to the storm sewer system and ultimately to the sea. This
prevents backup of the sewage within the system and perhaps
flooding of the pump station itself. Again, this'should be
accomplished starting at the downstream station and working
upstream. The drawback to the by-pass is the contamination of
the outfall area along the seashore.' MiLny of the major pump
stations are located near Gulf Street and the overflows
discharge to the Gulf via the storm drainage'system. The
outfalls are not designed to diffuse the sewage and it is
Roorly mixed with the seawater. Incoming tides tend to push
the sewage to the beach and cause foul odors along the beach.
Therefore the strength of the odors is influenced not only by
the quantity of sewage entering the sea, but-also by wind and
tidal action. We surveyed several beach areas and found this
to be the problem at each outfall location. This situation is
the primary cause of foul odors at present. The expedient
construction of an outfall with diffuser io increase mixing
-and reduce odors is not practical. Chemical addition at the
by-pass may have some effect and the city may wish to
experiment with the addition of ferric chloride, chlorine., or
hydrogen peroxide. We understand from the wastewater
treatment plant personnel that such chemicals are in short
supply and may not be available. It is our opinion that it
would be expensive and have limited success, if any. Time and
money would be better spent repairing the numia stations. once
zft stations are on-line, by-passing to the sea
will no loncler be recmired and the odors due to the bypassing
along the beach areas at the outfalls will be eliminated.
The pump stations and especially the Rrimary stations
with 4 or more Pumps may not need to be 100% operational to
function satisfactorily. As an example, perhaps only 4 out of
6 pumps should be repaired under this emergency situation
because with reduced population, reduced f lowrates can also be
expected. Then the available assets can'be used where they
will do the most good. We also discovered that the main pump
stations have mechanically cleaned bar- screens and grit
removal mechanisms. We place a low priority on repairing that
equipment in the short term. It is more important: to pump the
wastewater than to remove grit at this. time. it(ite that
additional grit will then be transported to the wastewater
treatment plants. This will be an especially significant
problem at the Rikka Plant -and possibly the Tahra Plant which
have no grit removal designed into the plants. 'Grit removal
must be accomplished by dewatering the aeration basins and
reidoval by hand or small front-end loader as before. This
will be r @ ired more often until all of the grit removal is
operational at the various pump stations.
The major pump stations which are currently flooded
should be left flooded and de-energized. pewaterinct the dry
21
27
Box ID = BX000000
Unit = CONST ENG LABS
Parent Organization = CORPS OF ENGS
Folder Title = SANITARY SEWAGE SYSTEM RECOVERY ASSESSMENT
Subject = SANITARY SEWAGE SYSTEM RECOVERY ASSESSMENT
Document Number = 129
Image file name = 00000028.tif
Document Page: First | Prev | Next | All | Image | This Release | Search