LARIMER COUNTY RURAL AREA ROAD STANDARDS

CHAPTER 5 – GEOTECHNICAL STANDARDS AND PAVEMENTDESIGN5.1 SCOPEThe purpose of this section is to present the Road Structural Design Standards required for useon all rural roads in Larimer County.5.2 GENERALRoads shall be designed in accordance with these and other referenced standards and soundengineering practice.This section provides the basic standards and design procedures for roadway pavements. Thedesign standards presented follow American Association of State Highway and TransportationOfficials (AASHTO) and Colorado Department of Transportation (CDOT) methods. Roads areto be constructed of surfacing materials as required by standards in Chapter 4 with base coursematerial (where required), and subbase material (where required), placed on compactedsubgrade. The use of full depth asphalt is generally not allowed but may be acceptable whendesigned, submitted, and approved by the Engineer in accordance with these standards. Whereapplicable, a pavement design must be approved by the Engineer prior to final plat approval.Pavement designs are not required for gravel surfaced roads.5.3 SOILS INVESTIGATIONIn order to design pavements for approval and acceptance by the County, sampling and testingmust be performed under the direct supervision of a registered professional engineer toevaluate the soil characteristics of the proposed development. Sufficient samples shall be takento properly evaluate all changes in soil character.5.3.1 Existing PavementFor investigation of existing paved roads the Engineer may require cores or nondestructivetesting methods of the existing pavement, analysis of the base structure andpossibly a soils investigation to determine whether an overlay is feasible or ifreconstruction is necessary.5.3.2 Soils Investigation Report ContentA soils report showing pavement design information, ground water levels, soil bearingcapacity, corrosiveness, and soil classification shall be required prior to the Engineer’sapproval of construction plans. In addition, each report shall include the following (referto Section 5.7 for combined Subgrade Investigation and Pavement Design Reportrequirements):1. Site location and description2. The following laboratory test reports with evaluations:a. Classification Tests1) Visual classificationLarimer County Rural Area Road Standards Page 5-1October 22, 2007