The contractor shall provide maintenance services to existing HACH equipment (Table 1). Contractor must show proof of manufacturer approval to provide maintenance services by providing a letter from the instrument manufacturer authorizing contractor to perform repair and maintenance services on the existing list of equipment (Table 1). The Contractor shall furnish all material, replacement parts, equipment, and labor to perform maintenance on the equipment under contract. The maintenance services shall consist of quarterly, and annual maintenance services as specified by the manufacturer of the equipment, as well as other “as-needed” scheduled maintenance. Maintenance services may include, but are not limited to the following: • Calibrating the equipment (new and existing) to factory standards • Changing colorimeters cells and windows • Performing all instrument software updates as needed • Replacing Bulbs on turbidity Meters • Others as needed maintenance, and services to maintain the equipment functionality