Provided that wherever heavy traffic is liable to pass over a drain
the covering of such drain shall not be less than 2 ft. in depth, or,
alternatively, cast-iron pipes of not less thickness than $\frac{5}{16}$ in. shall
be used.

Inlets to drains.

(8.) With respect to inlets into drains the following provisions
shall apply :—

$(a.)$ No inlet into any drain shall be provided within or underneath a building unless such inlet may be necessary to connect a water-closet or a slop-sink or urinal to such drain.

Gully-traps.

$(b.)$ Every opening into any drain other than an opening provided for the connection of a water-closet or slop-sink or urinal, or for the purposes of inspection or ventilation as hereinafter provided, shall be fitted with a gully-trap or with a grease-trap.

$(c.)$ Every gully shall be of approved siphon type of self-cleansing form, with a water-seal of not less than $2 \frac{1}{2}$ in. or more than $3 \frac{1}{2}$ in., shall be provided with dished top or shall be surrounded by a cement or brick coping, and the height of such top or coping shall be not less than 3 in. above the level of ground immediately adjacent, and every coping shall have the surface rendered in cement mortar and steel-trowelled.

Grease-traps.

$(d.)$ Every grease-trap shall be of approved type, and shall be provided wherever in the opinion of the Engineer such grease-trap is necessary.

$(e.)$ In the event of it being in the opinion of the Engineer not desirable to provide a gully-trap outside any building, he may authorize the placing of a gully-trap inside or under any building with such means of communication to the open air as he may direct.

Junctions in drains.

$(9.)$ $(a.)$ Every junction between two drains shall be effected either by the use of a Y junction-pipe or by the construction of a manhole of approved design, and every branch drain shall join the main drain and every drain join a sewer obliquely at such angle that the flow of the sewage in the two channels shall tend to be in the same direction.

$(b.)$ Wherever a soilpipe or a ventilation-pipe joins vertically to a drain, an approved bend pipe curving in a radius of not less than five times the diameter of the pipe shall be used.

Cleaning-eyes to be provided at certain points.

$(10.)$ In the course of every drain there shall be provided a cleaning-eye or access opening into the drain at the following positions, that is to say :—

$(a.)$ At the point at which the drain joins the sewer;
$(b.)$ Immediately within the boundary of the premises for which such drain is provided;
$(c.)$ At every Y pipe or other junction of such drain with another drain;
$(d.)$ At every change in the direction of such drain;
$(e.)$ At intervals of not more than 30 ft. in the course of such drain;
$(f.)$ Immediately on the sewer side of every junction with any water-closet or gully-trap in the course of such drain;
Such eyes or openings shall be not less than the diameter of the drain, and wherever the Engineer shall so decide such access opening shall be made in the form of an inspection-chamber of approved design and covering.

NOTE.—Wherever the sewers are so constructed, laid, and ventilated as to ensure that sewer gases shall not accumulate, the intercepting-trap may be dispensed with except in special cases as permitted in this clause. In the case of old or ill-ventilated sewers the intercepting-trap should be made compulsory for every house connection.

Intercepting-traps to be provided where specified.

$(11.)$ Where the Engineer is of opinion that an intercepting-trap is necessary, such intercepting-trap shall be provided at a point determined by him on the sewer side of that junction with any branch