410A-XXX

Natural resources conservation service
conservation practice sPECIFICATION

410a - grade stabilization - rock drops

NRCS, CA
July 1996

I. Scope

The work shall consist of furnishing materials and installing rock drop structures at the locations and to the lines, grades, elevations, and cross- sections as shown on the drawings or as staked in the field.

II. Materials

A. Rock

Rock shall be sound, dense and durable. The rock and the source shall be approved by the Engineer prior to installation. Rock shall be angular to subangular in shape with the greatest dimension not greater than three times the least dimension; and should the least dimension be six inches or greater, then the greatest dimension shall not be greater than two times the least dimension. The rock shall be fairly well graded. The gradation of the rock shall be as specified on the "Practice Requirement" sheet.

B. Filter Material (when specified):

Sand and Gravel--The filter shall consist of a blend of clean sand and gravel, which is not subject to decomposition in air or water and is free from roots and other foreign materials. The size and gradation limits shall be as specified on the drawings or as listed on the "Practice Requirement" sheet.

Geotextile fabric. - The type of geotextile fabric required shall be stated in the "Construction Requirement" sheet, and the fabric shall be conformed to Practice Specification "Geotextile Fabric".

III. Subgrade Preparation

The subgrade surfaces on which the rock is to be placed shall be cleared and excavated to grade prior to placement of rock. The subgrade shall be inspected prior to the placement of rock.

IV. Placement

The rock shall be placed in such a manner as to avoid displacement of the under lying materials. The rock shall be delivered and placed in a manner that will insure that the rock in place shall be reasonably homogeneous and firmly in contact one to another with the smaller rocks and spalls filling the voids between the larger rocks. Smaller rocks shall not be grouped as a substitute for larger rock. Some hand placement of rocks will be necessary to achieve the final finish surface.

V. Vegetative Cover

Unless otherwise specified, a protective cover of vegetation shall be established on the disturbed area. The planting of vegetative materials shall conform to the requirements of Practice Specification 342, Critical Area Planting.

VI. Special Measures

Measures and construction methods shall be incorporated as needed and practical that enhance fish and wildlife values. Special attention shall be given to protecting visual resources and maintaining key shade, food, and den trees.

VII. Construction Operations

Construction operations shall be done in such a manner that erosion and air and water pollution are minimized and held within legal limits. The owner, operator, contractor or other persons will conduct all work and operations in accordance with proper safety codes for the type of construction being performed with due regards to the safety of all persons and property.

The job shall be completed in a workmanlike manner and present a pleasing appearance.