GENERAL42758 - Laserfiche WebLink

Home Browse Search

land. Surface disturbances have been limited to the colluvial deposit, with no surface disturbance in the present flood plain. No further surface disturbance is proposed. The application describes the unconsolidated deposit as being composed of colluvial material resulting from mass wasting and slope wash from the steep slopes rising to the north of the permit area (see Map 11). The text indicates that, since settlement in the early 1900's, the area was graded to allow construction of the Fire Mountain Canal and accommodate flood irrigation. The affected area occupies a transitional area (mapped as Qc on Map 2 of the application) between the flood plain and terrace complex below (mapped as Qa on Map 11 of the application) and the steeper upland slopes to the north of the permit area. It is the Division's opinion that this transitional area is more appropriately considered to be an upland area rather than part of the flood plain and terrace complex as defined in sections 1.04(10), (142) and (147) of the Rules and Regulations. Although colluvial deposits can be considered to be part of unconsolidated alluvial deposits in many cases, in this particular instance the deposits are fairly deep and appear to be underlain by bedrock or other fairly consolidated material (on the basis of test pits and observation by Division personnel). The proposed permit area is also on a moderately steep slope (16%) which the applicant suggests was previously graded to accommodate agricultural activity. The type of irrigation practiced on these colluvial deposits consists of diverting the flow from a nearby irrigation canal into a system of furrows. This type of irrigation is the only feasible practice under such steep slope constraints and is considered to be artificial subirrigation rather than flood irrigation as strictly defined in Rule 1.04 (48). Based on these considerations of the nature of the material, steepness of slopes and irrigation practice the Division finds that the permit area is more appropriately considered to be within the upland area relative to the alluvial valley floor, and is not within the flood plain and terrace complex. The Division therefore makes a negative determination for the presence of alluvial valley floors in the specific area of proposed disturbance for the Terror Creek operation. The valley bottom below the proposed disturbance (below the existing railroad grade) is considered to be an alluvial valley floor. The Division therefore has to make the required findings for the impact of the disturbance on an adjacent alluvial valley floor. These findings are presented below. B. Alluvial Valley Floor Findings Pursuant to Rules 2.06.8 and 4.24.2, the Division is required to make specific written findings on the effect of mining upon any Terror Creek Loadout Page 20