If, in any case, it is impractical to locate sewerage facilities and water supply facilities with the separations required by the provisions of Section 7-4.03 and 7-4.04 of this chapter, they may be located closer to one another provided:
(a) The joints of the lines in the reaches of each line where the required separations are not maintained shall possess the necessary strength and durability to prevent the escape of the contents of the lines under such adverse conditions as corrosion, strains due to temperature changes, settlement, and superimposed loads; and
(b) The designs of the facilities, where required separation is not maintained, are approved by the Public Works Director. The Public Works Director shall issue standards of design for facilities which are acceptable within the required separation area. Facilities meeting such standards may be located within the required separation area without the specific approval required by this subsection.
(§ 8603, T.O.O.C.)