required and how often it is needed; the special
lubricants or coatings needed; and a record of all
work done on the unit, including the labor, parts,
and total cost. This data should be considered
when planning to buy new equipment and mak-
ing a maintenance schedule.
Making a maintenance schedule requires
careful thought. Good records can serve as a
guide. Some large treatment plants now use a
computer to plan maintenance schedules and keep
records up-to-date. Preventive maintenance
should be scheduled so it can be done during good
weather and not during times of peak load at the
plant. Also, the schedule must leave time for
repair work. A large chart showing what needs
to be done daily, weekly, monthly, quarterly,
semiannually, and annually can help in setting up
a work schedule.
A spare parts inventory should be established.
Many spare parts must be ordered several days
or weeks before they are delivered. These spare
parts should be stocked at the treatment plant so
the plant wont have to be shut down until the
part arrives. A list or inventory of spare parts
makes reordering simpler. A written record of
parts used and replaced should be kept. The
operator should record the date an item was
ordered, the date delivered, its cost, and the name
of the supplier, each time a part is ordered and
In addition to the above records you must also
maintain performance records. There are three
types of performance records. These are the
laboratory records, operators log, and NPDES
A complete set of laboratory records should
be kept for all laboratory tests. The laboratory
record should have the date and time the sample
was taken, the method used to take the sample,
the name of the person who took the sample,
where the sample was taken, the test performed
on the sample, and the results of the laboratory
test. These records should be kept in a bound
notebook so they can be used as a part of legal
testimony about the operation of the plant if need
be. A monthly or quarterly report is also required
at most plants.
A monthly report is required for all
wastewater plants on a military installation. Since
no two treatment plants are exactly the same, the
operator will find that a special log designed for
the treatment plant is helpful. The operator should
report on special features of the treatment plant
under the blank columns in the log. Operators at
each treatment plant are required to complete the
log. Navy plant operators use the Wastewater
Treatment Plant Operating Record, NAVFAC
Finally, every treatment plant that discharges
to a body of water must get an NPDES permit
from the EPA or the designated state agency. The
permit lists standards for the effluent, tests re-
quired, how often the tests must be run, and the
sampling method of each test. The treatment plant
must submit a monthly or quarterly report to the
EPA or the designated state agency with all the
laboratory tests required by the permit. These
reports and laboratory records must be kept for
at least 3 years.
Use performance records to check the plant.
The performance records at a treatment plant can
provide good process control data to the operator.
Results of laboratory tests that differ a lot from
previous records may show an equipment
breakdown, an industrial waste discharge, or a
break in the collection system. Table 10-12 shows
Table 10-12.Variations in Performance and Some Common Causes
BOD5 (or COD):
Increased organic loading,
Identify source of increase. If overloading is
Population growth. Im-
permanent, adjust treatment plant processes for
maximum efficiency. Require adequate pretreat-
ment. Enforce sewer use regulations if violations
are found. Install holding tanks (ponds) if
feasible. Modify or expand treatment units.
Freshen by aeration or chlorination.
Septic conditions in treat-
Check on detention time and sludge pumping
ment plant units.
schedule. See if dissolved oxygen requirements
of aerated units are being met.