Civil Engineering Reference
In-Depth Information
terior conduits or duct banks may be required for site and parking lighting, security
gates or checkpoints, and for surveillance equipment.
An outdoor standby generator or fuel storage facility will require appropriate space
and truck access.
Distributed facilities on a site may require an extensive system of underground duct
banks and pullboxes or manholes. Space must be allocated for such systems as site
utility systems are planned.
MAJOR ELECTRICAL EQUIPMENT AND SPACE
Major electrical equipment can be quite large and requires suitable space and envi-
ronment. It is wise to plan dedicated space for electrical switchgear, motor control
centers, and panels—preferably in a separate room from the process where possible.
Obtaining realistic dimensions for electrical equipment will aid greatly in the planning
process. There are National Electrical Code requirements for working space clearance
and entrances into the work space, and it is suggested to review these requirements
with an eye toward the size of electrical equipment expected.
Switchgear and motor control centers can be mounted outdoors in NEMA 3R rain-
tight enclosures on concrete pads where indoor space is limited. Maintenance can be
more difficult in cold, rainy or snow climates. In addition, electronic components such
as VFDs may require heating and / or air conditioning. It is always better to install
such equipment in buildings where possible.
HAZARDOUS AND CORROSIVE AREAS
Steps should be taken to avoid installing all but essential electrical and electronic
equipment in hazardous (NEC-classified areas) and / or corrosive areas. If available,
equipment should be installed in adjacent nonclassified and / or cleaner areas. Electrical
equipment and its maintenance and service will be more costly and difficult when
installed in hazardous and / or corrosive areas.
Hazardous areas require explosion-proof-rated equipment, which usually consists
of bolted, heavy enclosures that make maintenance and inspection difficult and tend
to discourage these essential activities.
On water treatment facilities, generally there are not any areas that are required
to be rated hazardous with respect to fire or explosion potential. Fuel-dispensing
or -storage areas would be a possible exception. Another area of concern is the storage
of powdered activated carbon (PAC). Local code officials have had differing views on
whether the carbon dust poses an explosion hazard. It is best in this instance to get a
ruling from the local code enforcement agencies prior to beginning design using this
chemical.
Any areas that store chlorine, or chlorine-based derivatives, should be classified as
corrosive.
INSTRUMENTATION
Almost every water system or facility can benefit from the use of a SCADA system.
SCADA systems are applicable for small water facilities with less than 100 input /
output points to large facilities with a 1,000 or more.
