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The affected area occupies a transitional area (mapped as Qc on Map 2 of the application) <br />between the flood plain and terrace complex below (mapped as Qa on Map 11 of the <br />application) and the steeper upland slopes to the north of the permit area. It is the <br />Division's opinion that this transitional area is more appropriately considered to be an <br />upland area rather than part of the flood plain and terrace complex as defined in sections <br />1.04(10), (142), and (147) of the Rules and Regulations. <br />Although colluvial deposits can be considered to be part of unconsolidated alluvial <br />deposits in many cases, in this particular instance the deposits are fairly deep and appear <br />to be underlain by bedrock or other fairly consolidated material (on the basis of test pits <br />and observation by Division personnel). The permit area is also on a moderately steep <br />slope (15 %), which the applicant suggests was previously graded to accommodate <br />agricultural activity. The type of irrigation practiced on these colluvial deposits consists <br />of diverting the flow from a nearby irrigation canal into a system of furrows. This type of <br />irrigation is the only feasible practice under such steep slope constraints and is considered <br />to be artificial subirrigation rather than flood irrigation as strictly defined in Rule 1.04 <br />(48). <br />Based on considerations of the nature of the material, steepness of slopes and irrigation <br />practice, the Division finds that the permit area is more appropriately considered to be <br />within the upland area relative to the alluvial valley floor and is not within the flood plain <br />and terrace complex. The Division therefore makes a negative determination for the <br />presence of alluvial valley floors in the specific area of proposed disturbance for the <br />Terror Creek operation. <br />The valley bottom below the proposed disturbance (below the existing railroad grade) is <br />considered to be an alluvial valley floor. The Division therefore has to make the required <br />findings for the impact of the disturbance on an adjacent alluvial valley floor. These <br />findings are presented below. <br />B. Alluvial Valley Floor Findings <br />Pursuant to Rules 2.06.8 and 4.24.2, the Division is required to make specific written <br />findings on the effect of mining upon any AVF's within the permit and adjacent area. The <br />findings for the North Fork AVF are presented below. Mining activity (construction of <br />the loadout facility) has already disturbed approximately 13 acres of land on the colluvial <br />slope. No further surface disturbance is proposed by the applicant. <br />Pursuant to Rule 2.06.8(5)(a)(i)(A)(I), the Division finds that the surface coal <br />mining operations would not interrupt, discontinue, or preclude farming on the <br />alluvial valley floor. Loadout operations on the colluvial slope will not physically <br />impact farming operations on the alluvial flood plain below. Groundwater is not <br />present in the colluvium in the permit area and surface water from above will be <br />diverted around the disturbed area. No future impact which might interrupt, <br />discontinue, or preclude farming on the flood plain is proposed. Thus operations at <br />Terror Creek would not interrupt, discontinue, or preclude farming on <br />previously - undisturbed portions of the alluvial valley floor. <br />2. Pursuant to Rule 2.06.8(5)(a)(i)(A)(II), the Division finds that the surface coal <br />mining operations would not materially damage the quality and quantity of water in <br />surface and underground water systems that supply those alluvial valley floors or <br />portions of alluvial valley floors. <br />21 <br />