5627 1ST AVE SE 2016-01-01 MF Import

Geotechnical Consultation Services Page 3 _ 93-1397 Hannabrook Rock Wall - Lots 39 thrnugh 45 July 26, 1993 ■ Pertormance of appropriate geotechnical engineering calculations to determine the appropriate rock siza for wall construction, ■ Development of geotechnical guidelines for rock wall construction, and ■ Provision of four copies of a letter report outlining the rock w2ll construction guidelines. This report has been prepared for this project and is for the exclusive use of Colony Crak and thair subcontractor only. The report should be provided to the rockery subcontractor for his esdmating purposes, but should not be considered sufficient to relieve him of the need to perform his own study to verify that site condRions are as anticipated in this letter. Sits Excavatlon Work The rockery contractor will need to excavate back iMo the eastern site slope for a sufficient distance to allow for the construdion of the proposed protective rock wall while creating sufficient space for the proposed building and yard areas. The estimated distance from the western I�t�erimeters to the exposed cut face is about ninety-one feet. The actual width of excavation ��:expected ta vary from lot to lot, but is likely to be on the order of between about six and twelve (12) feet. Once the excavation into the east slope is completed on any given lot it will be necessary to dig the keyway excavation. The keyway is to cxeate an area capable of capturing groundwater seepage from behind the protective wall as well as providing a means of helping preventing sliding of the wall over time. Rock Wall Construction Once the appropriate level of keyway and wall excavation has been performed,the protective rock wall mav be constructed. A typical detail showing the highest portion of thA wall is presented on Sheet 1 of 1,attached,for your information. The following paragraphs describe the construction process in more detail. • General: The owner should be aware that a protective rock wall is not considered a retaining structure in the way one would consider, for example, a reinforced concrete retaining wall. The primary function of a rock wall is to protect the soil face in front of which it is constructed against tha elements and to help reduce the potential for erosion.