Safety grating for riser of a septic tank

An assembly comprising:

• (a) a grating for impeding the downward passage of small objects when a lid is absent from a riser assembly that comprises
• a central length axis;
• a hub, centered on said central length axis;
• a multiplicity of arms extending radially outwardly from the hub, each arm having a first end attached to the hub, an opposing second end that is a free end, and a length therebetween;
• wherein at least one arm of said multiplicity of arms is hingedly attached to the hub and thereby wholly or partially pivotable in a plane within which lies said grating central length axis, to thereby change the distance between the arm free end and the grating central length axis;
• wherein, when said at least one arm is fully extended, the grating has an arch shape in a plane within which lies the central length axis and the free ends of said multiplicity of for arms lie around a circle;
• and
• (b) a first upward-extending riser that comprises
• a riser central length axis that is substantially parallel to said grating central length axis,
• a riser first end having an associated first opening that faces downwardly,
• a riser second end having an associated second opening that faces upwardly, the second opening larger than the first opening;
• a circumscribing wall running from the first end to the second end, the wall shaped at least in part as a truncated cone and defining a riser interior space;
• wherein the grating is positioned within the riser interior space with the hub is-spaced apart along the riser central length axis from the riser second end;
• wherein each grating arm free end is in contact with the truncated cone shaped part of said circumscribing wall;
• and
• wherein each grating arm free end extends downwardly from the hub and is closer to said riser first end than is the hub.

A method of installing a grating within a riser assembly for impeding the downward passage of small objects when a lid is absent from the riser which comprises:

• (i) providing a first riser having
• a riser central length axis that is substantially vertical and that runs from a riser first end to a riser second end,
• the riser first end having a first circular opening and associated first diameter,
• the riser second end having a second opening, the second opening larger than the first opening, and
• a circumscribing wall running from the first end to the second end, the wall shaped at least in part as a truncated cone and defining a first riser interior space,
• wherein the second end faces vertically upwardly;
• (ii) providing a second riser identical to the first riser and mating the larger opening ends of the first and second risers, wherein the second riser smaller opening faces vertically upward;
• (iii) providing a grating comprising
• a central length axis;
• a hub, centered on said central length axis;
• a multiplicity of arms extending radially outwardly from the hub, each arm having a first end attached to the hub, an opposing second end that is a free end, and a length therebetween;
• wherein at least one arm of said multiplicity is wholly or partially pivotable in a plane within which lies said central length axis, to thereby change the distance between the arm free end and the grating central length axis;
• wherein, when said at least one arm is fully extended, the grating has an arch shape in a plane within which lies the grating central length axis and the free ends of said multiplicity of arms lie around a circle that has a diameter greater than said riser first diameter;
• (iv) moving the grating vertically downward through the said smaller upward-facing opening of the second riser and into said interior space of the first riser while pivoting said at least one arm in said plane in which lies the grating central length axis, to enable passage of the grating through said smaller upward-facing opening;
• and,
• (v) contacting the free end of each grating arm with the truncated cone part of the circumscribing wall of the first riser with the grating central length axis aligned with the riser central length axis, so the grating has an arch shape in a plane within which lies the central length axis of the first riser and so the grating hub is closer to the first riser second opening than are the free ends of the grating.