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 making 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 won't 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 delivered.

In addition to the above records you must also maintain performance records. There are three types of performance records. These are the laboratory records, operator's log, and NPDES forms.

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 11340/1 (6-75).

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 required, 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