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11 MIDSIZED SUBSURFACE SEWAGE TREATMENT SYSTEMS 7081.0140 <br />(f) School (no gym, no cafeteria, and <br />no showers) student 14 <br />(g) School (with cafeteria, no gym and <br />no showers) student 18 <br />(h) School (with cafeteria, gym, and <br />showers) student 27.5 <br />(i) School (boarding) student 95 <br />(j) Church seat 4 <br />add for each meal prepared 5 <br />(k) Assembly hall seat 4 <br />(8) Miscellaneous <br />(a) Public lavatory user 5 <br />(b) Public shower shower taken 11 <br />* Waste other than sewage is only allowed to be discharged into the system if the waste is suitable to be <br />discharged to groundwater. <br />Unless otherwise noted in Table 1, the flow values do not include flows generated by employees. A <br />flow value of 15 gallons per employee per eight -hour shift must be added to the flow amount. Design flow <br />determination for establishments not listed in Table 1 shall be determined by the best available information <br />and approved by the local unit of government. <br />B. The measured design flow of sewage for MSTS serving other establishments is determined <br />by averaging the measured daily flows for a consecutive seven-day period in which the establishment is at <br />maximum capacity or use. <br />Subp. 2. Waste concentration. If concentrations from the sewage tank to the soil dispersal system <br />are expected to be higher than 170 mg/1 BOD (or 125 mg/1 CBOD5), 60 mg/1 TSS, or 25 mg/1 of oil and <br />grease, an estimated or measured average concentration must be determined and be acceptable to the local <br />unit of government. System design must account for concentrations of these constituents so as not to cause <br />internal system malfunction, such as, but not limited to, clogging of pipes, orifices, treatment devices, or <br />media. <br />Statutory Authority: MS s 115.03; 115.55 <br />History: 32 SR 1400; 35 SR 1353 <br />Published Electronically: March 11, 2011 <br />7081.0140 INFILTRATION. <br />The design flow must also include 200 gallons of infiltration and inflow per inch of collection pipe <br />diameter per mile per day with a minimum pipe diameter of two inches to be used for the calculation. <br />Flow values are allowed to be further increased if the system employs treatment devices that are exposed <br />to atmospheric conditions that will infiltrate precipitation. Flow estimates as calculated in this chapter shall <br />not be relied upon for the design of collection systems. <br />Copyright ©2014 by the Rev <br />so <br />of Statutes, State of Minnesota. All Rights Reserved. <br />