_INSPECTION - C1994082 (41) - Laserfiche WebLink

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III. COMMENTS-COMPLIANCE Below are comments on the inspection. The comments include discussion of observations made during the inspection. Comments also describe any enforcement actions taken during the inspection and the facts or evidence supporting the enforcement action. Pond 14 Watershed There are two primary drainage systems in the Pond 014 watershed, YPM-14 and YPM-3 (consisting of YPM 3-2A and various tributaries). YPM-14 is tributary to YPM 3-2 a short distance upstream of Pond 014. Upper tributaries to YPM 3-2 are YPM 3-1 (Photos #508 foreground,#507, and#510) and YPM 3-IA (Photo #508, background, and#509). YPM 3-1 and YPM 3-1A are both stable riprapped channels. YPM 3-2 From its upper end at the confluence of YPM 3-1 and YPM 3-IA, down to a point approximately 150' below fenced shrub plot SP06-3, YPM 3-2 is a typically stable riprapped channel, with riprap uniformly distributed in the channel. The segment immediately below the shrub plot, shown in#MLT7151132a, is typical. Further downstream from the shrub plot, the character of the channel bed changes. Riprap has been redistributed by high flows through the steeper segments, forming a step-pool channel morphology. This channel type is typical of high gradient streams with cobble substrate, and may be stable over the long term,but will need to be monitored and remedial measures taken if there is channel "jump-out",bank scour outside of the riprapped zone, or headward erosion within the channel. A typical "step-pool" segment is shown in#MLT7151139. #MLT 7151136b shows a location of incipient bank scour at a slight curve in the channel; riprap placement along the bank in this location may be warranted. A number of short hillslope gullies were observed in the immediate vicinity of the SP05-1 and SP06-3 shrub establishment plots in the YPM 3-2 watershed. Most of the gully features originated due to diversion and resultant concentration of flow to protect the shrub plot areas from erosion during initial establishment. During inspection on 8/12/09, it was noted that these gullies had recently been reclaimed, and measures had been implemented to break up concentrated flow and direct such flows away from repaired gullies and into the stable channel. YPM-14 YPM-14 is a typically stable riprapped channel in its upper reaches,but its lower segment just above the confluence with YPM 3-2 is an extremely steep gradient segment with very large riprap. The segment was measured at 44%; design grade is 45% (Photo #512). The segment appeared to be stable, with the exception of minor side-cutting. Maintenance of this channel was completed prior to inspection of 8/12/09. 12