29.  Includes depreciation and interest on investment.

M.G..  Million gallons.

31.  City has a sewage farm of about 518 acres, and the effluent from the septic tank is used to irrigate about 450 acres of the farm. The cities of Pasadena, South Pasadena, and Alhambra have purchased a new sewage farm where they plan jointly to purify their sewage.

32.  “Same force of men can handle one acre as one-half acre, or twice as great a flow.”

33.  Does not include interest and depreciation.

34.  In winter draw as little as possible; in summer draw as much as possible; the aim being to leave the tanks as free as possible from good sludge when cold weather comes.

35.  Operation of Imhoff tanks costs nothing as city allows a man to use two acres of land to compensate him for caring for tank. The septic tank is attended to only once a year, and probably does not cost more than $30 annually.