A. Existing Equipment & Conditions 1. Clarifier Mechanisms Existing Clarifier Information Item Detail Clarifier tank Concrete Tank diameter 95 ft. Base of wall elevation (inside) 575.75 Top of wall elevation 592.0 Top of weir elevation 589.6 Launder elevation 588.1 Side water depth ~14 ft. Side wall height (inside) ~16 ft. Bottom slope to center 1:12 Sludge rake arm Mechanical scraper Average flow rate 2.7 MGD Maximum flow rate 5.4 MGD Peak flow rate 7.5 MGD SVI 130 ml/g MLSS 300 mg/l 2. Classifiers The existing Grit Classifiers are Wemco Classifiers 1000C @ 10psi B. Requirements The design engineer shall provide drawings and specifications to replace the mechanisms for secondary Clarifiers No. 1 and No. 2, including the weirs and scum baffles. The design engineer shall provide drawings and specifications to replace Grit Classifiers No. 1 and No. 2. The design shall require that the contractor verify any conditions that could impact the installation or configuration of any equipment. 1. Clarifier Mechanisms The clarifier mechanisms to be replaced include: Drive assembly Support column Feed well Sludge discharge assembly Sludge rack assembly Influent assembly within the Tank Skimmer arm assembly Walkway Platform Scum baffle assembly "V-notched"weir assembly Design of the repair of the bottom of the clarifier tanks will be prepared as an additive bid item to be determined after emptying, removing existing equipment, and cleaning the clarifier tank. Design Criteria: UMC will use Oxidation Ditch No. 1 with any combination of two secondary clarifiers, i.e., No. 1, 2, or 7, in operation. Either of the two clarifiers to which the project applies can be isolated from the influent flow, while keeping the other two clarifiers in operation. The scraper mechanism shall be a spiral two-arm mechanical scraper with a flexible "squeegee" on the bottom. The skimmer arm shall be a full radius unit that drains to the edge, not to the center. An after-market weir cleaning device on the end of the skimmer arm shall be specified as Ford Hall. After all equipment is removed from a clarifier, the concrete walls and floor of the tank shall be cleaned and pressure washed. The cleaning will allow an inspection of the concrete surfaces. A decision will be made about the amount of repair and the most effective method of repair. Additive bid items: Spot repairs equal to 25 SF total area. Recoat the floor of the tank with epoxy grout.
