N.Y. Comp. Codes R. & Regs. tit. 12, § 23-4.2 – Trench and area type excavations.

(a) Whenever any person is required to work in or is lawfully frequenting any trench or excavation five feet or more in depth which has sides or banks with slopes steeper than those permitted in Table I of this Subpart, such sides or banks shall be provided with sheeting and shoring in compliance with this Part (rule). Such sheeting and shoring system shall be in contact with the sides or banks of such trench or excavation. A designated person shall carefully inspect such sheeting and shoring at least once each day and more frequently in the event of rain, the presence of additional surface or ground water from any source, excessive ground vibrations or whenever additional loads of any kind have been imposed near or adjacent to such excavation. Additional protection against slides and cave-ins shall be provided whenever necessary. Any trench or excavation in clay, sand, silt, loam or nonhomogenous soil which has sides or banks more than three feet but less than five feet in depth shall be provided with side or bank protection in compliance with this Part (rule). Such side or bank protection shall not be required where an employer maintains on file at the excavation site a dated certification in writing by a designated person who is qualified by training and experience indicating that such person has examined the sides and banks and has found them to be stable and not subject to failure or cave-in. Such certification shall be available for examination by the commissioner.
(b) Where the sides or banks of a trench or area type excavation may be sloped back without causing subsidence or damage to buildings, structures, utilities, roads, streets, highways or similar facilities, sloping of the excavation sides or banks may be used as protection in lieu of the sheeting and shoring required by this Part (rule), provided such sloping conforms to the values set forth in Table I of this Subpart. Such sloping of the excavation sides or banks may be used in combination with sheeting and shoring. When such a combination is used, a level bench at least 24 inches in width shall be left between the toe of the sloped section and the braced section. The sheeting of the braced section shall extend at least 12 inches above the elevation of such level bench.
(c) Any unbraced sloped excavation which extends below the ground water table, especially adjacent to rivers, reservoirs or other bodies or sources of free water, shall be under the direct supervision of an experienced person designated by the employer.
(d) In any excavation with a combination of sloped unbraced sides or banks near the surface and vertical sheeted and shored sides or banks near the bottom, the steepest allowable slope of such unbraced portion of the sides or banks shall be based on the total excavation depth. (See Table I of this Subpart.)
(e) Where any side or bank of an excavation is undercut and has a reverse slope toward the trench centerline creating a vertical load on the sheeting and shoring, such sheeting and shoring shall be designed by, and installed in accordance with the specifications determined by, a professional engineer licensed to practice in the State of New York. Such sheeting and shoring shall be designed to support the vertical load imposed by the overhanging material as well as the load imposed by the adjacent ground.

(f) Excavated material and other superimposed loads shall be placed at least 24 inches back from the edges of any open excavation and shall be so placed or piled that no part thereof can slide, fall or roll into the excavation. Such 24-inch required clearance may be reduced if the employer installs a barrier or similar retaining device which is designed and constructed to prevent excavated material from falling into the excavation.

TABLE I

STEEPEST ALLOWABLE UNBRACED SLOPES

Depth of Excavation
Type of Soil or Rock	5 to 10 ft.	Over 10 ft.
Stiff cohesive soil	1½ vertical on 1 horizontal	1 vertical on 1 horizontal (trench) 1 ½ vertical on 1 horizontal (area)
Noncohesive soil	1 vertical on 1 horizontal 1 vertical on 1 ½ horizontal (when subject to vibrations)	1 vertical on 1 horizontal 1 vertical on 1 ½ horizontal (when subject to vibrations)
Soft cohesive or wet flowing soil	1 vertical on 1 horizontal 1 vertical on 1½horizontal (when subject to vibrations)	1 vertical on 1½ horizontal (trench) 1 vertical on 1 horizontal (area) 1 vertical on 1 ½ horizontal (when subject to vibrations)
Stable rock	Vertical sides permitted	Vertical sides permitted
Unstable rock	1½ vertical on 1 horizontal	1½ vertical on 1 horizontal

Notes: The slopes given in Table I are the steepest allowable. Conditions may occur requiring the use of flatter slopes to prevent slope failure and subsidence of adjacent areas. A slope shall start from the bottom of each side of an excavation or where the lower portions of such sides consist of stable rock from the top of such rock.

(g) All sides or banks, slopes and areas in and adjacent to any excavation shall be stripped and cleared of loose rock or any other material which may slide, fall, roll or be pushed upon any person located in such excavation.
(h) Any open excavation adjacent to a sidewalk, street, highway or other area lawfully frequented by any person shall be effectively guarded. Such guarding shall consist of a substantial fence or barricade. As an alternative, such guarding may consist of an extension of the sheeting above the ground surface adjacent to the excavation to a height of at least 42 inches above such adjacent street, highway or other area lawfully frequented by any person. In lieu of such guarding, protection may be afforded by a substantial covering installed over such excavation. Such covering shall consist of planking at least two inches thick full size, properly supported exterior grade plywood at least three-quarters inch thick or material of equivalent strength. Where it is possible that the movement of vehicles or other heavy equipment will take place over such covering, the covering shall be of sufficient strength to withstand such loading without structural failure of the covering or of the support system.
(i) Where no work is being performed in an unattended open excavation which has substantially vertical sides or banks three feet or more in depth, such excavation shall be effectively guarded on all open sides regardless of the location of such excavation. Such guarding shall consist of a fence, a barricade or a safety railing constructed and installed in compliance with this Part (rule). As an alternative, such guarding may consist of an extension of the sheeting above the excavation to a height of at least 42 inches above the adjacent ground, grade or equivalent level. In lieu of such guarding, protection may be afforded by a substantial covering installed over the excavation. Such covering shall consist of planking at least two inches thick full size, properly supported exterior grade plywood at least three-quarters inch thick or material of equivalent strength. Where it is possible that the movement of vehicles or other heavy equipment will take place over such covering, the covering shall be of sufficient strength to withstand such loading without structural failure of the covering or of the support system.
(j) Temporary sheet piling installed in an excavation to permit the construction of a retaining or structural wall shall be left in place until such wall has developed adequate strength to support any load intended to be imposed upon such wall.
(k) Persons shall not be suffered or permitted to work in any area where they may be struck or endangered by any excavation equipment or by any material being dislodged by or falling from such equipment.
(l) The sides of any excavation in stable rock may be vertical and are not required to be provided with sheeting and shoring. Such sides shall be scaled and kept free of all loose rock or material that may be dislodged or may fall into such excavation.