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Orono High School Phase II Renovations Plumbing Plan No. 096474 Page 2 June 15, 2009 3. At that point where the proposed 2-inch waste serving the three lab sinks(S-4,2 d.f.u. each)connects to the existing 2-inch waste riser serving the lab sink(S-4)shown on waste and vent riser diagram, Detail No. 3, Sheet No.M412,a vertical 2-inch stack is shown to serve 8 d.f.u. which complies with Minnesota Rules, part 4715.2310, subpart 3, since a 2-inch stack for not more than 3 stories or branch intervals may serve up to 9 d.f.u. However,when the stack turns horizontal on the floor plan, Sheet No. M102, Gridlines S/11,the system is undersized since a 2-inch horizontal drain can only accommodate 6 fixture units at a slope of 1/4-inch per foot,this portion of the system is undersized(see Minnesota Rules,part 4715.2310, subpart 2). Verify that a code complying plumbing system will be installed. 4. On waste and vent riser diagram,Detail No. 5, Sheet No.M411,at that point where the 2-inch and 3-inch horizontal wastes from the branches serving the fixtures shown on Detail No. 7, Sheet No.M411, connect to the waste system,a 3-inch horizontal waste branch is shown to serve 34 d.f.u. This branch is also shown as 3-inch on the waste and vent riser diagram,Detail No. 2, Sheet No.M408. Since a 3-inch horizontal drain can only accommodate 32 fixture units at a slope of/s-inch per foot,this portion of the system is undersized (see Minnesota Rules,part 4715.2310, subpart 2). Verify that a code complying plumbing system will be installed. 5. Verify that the existing water supply and waste systems are sized to accommodate the added fixtures(see Minnesota Rules,part 4715.3800 and part 4715.2310). 6. Verify that the required cleanouts will be installed: a. The distance between cleanouts in horizontal piping shall not exceed 50 feet for pipe 3 inches or less in size,or not over 100 feet for pipe 4 inches and greater in size(see Minnesota Rules,part 4715.1010). b. Cleanouts shall be of the same nominal size as the pipes they serve up to 4 inches in size (see Minnesota Rules,part 4715.1010). A cleanout must be installed where there is an increase in pipe size from 2 inches to 3 inches and from 3 inches to 4 inches. c. Each horizontal drain branch,including floor drain branches, shall be provided with a cleanout at its upper terminal,except that a fixture trap or a fixture with an integral trap,readily removable without disturbing concealed piping,may be accepted as a cleanout equivalent for this purpose(see Minnesota Rules,part 4715.1000). d. It is recommended that a cleanout be provided where new waste and vent piping connects with existing plumbing to facilitate required testing of the new installation. 7. Faucets equipped with threaded hose connections must be provided with approved backflow preventers(see Minnesota Rules,part 4715.2110,DD). This shall include the serrated nozzle faucets in the science classrooms designed to accept rubber hose connections,the laundry tub faucet,and the'/4-inch threaded drain connection to the domestic water double-walled plate and frame heat exchanger(HX-1). 8. The water supply to any dishwasher in which the supply opening is located below the spill line of the machine must be protected with a vacuum breaker(see Minnesota Rules,part 4715.1250). 9. Potable water connections to boiler feed water systems, cooling systems,or other liquid systems in which water conditioning chemicals may be introduced shall be made through an air gap or be provided with an approved backflow preventer located in the potable waterline before the point where such chemicals may be introduced(see Minnesota Rules,part 4715.1940).