2012-01-17_REVISION - M2005050 (2)

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,M_20 ()5 -05-0 S 13taos Cazier, Tim From: Cazier, Tim Sent: Thursday, January 19, 2012 4:58 PM To: 'jamespirc @aol.com' Subject: RE: Clarification of Citations Mr. Pierce, As I interpret Pennsylvania's Detail 8, the geotextile is covered by 2xd50 ( riprap). I don't think the few inches proposed for J Birds will be sufficient. Tim Cazier, P.E. Environmental Protection Specialist Colorado Division of Reclamation, Mining and Safety 1313 Sherman Street, Room 215 Denver, CO 80203 ph: 303 - 866 -3567 x8169 fax: 303-832-8106 tim.cazier(a_state.co.us From: "a� mespirc @aol.com [mailto:jamespirc @aol.coml Sent: Tuesday, January 17, 2012 5:52 PM To: Cazier, Tim Subject: Clarification of Citations Mr. Cazier - My intent was indeed to show examples of the elements used in the design rather than an example of a matching design. Pennsylvania's emergency spillway design shows the geotextile filter as the default in the detail. It does not place a limitation on the slope of the spillway nor does it mandate a maximum slope on the embankment. It also ends the riprap with a non - concrete cutoff. These are the core elements of the JBird and Prince Albert spillway designs. Due to concerns about erosion in the throat of and on the crest of the spillway I have extended the geotextile as a liner to the inside face of the berm (this is also to reduce the the chance of water channeling under the fabric). The example from the Yukon heap leach copper project was merely included as an example of the use of a gravel layer as protection (primarily against UV). It was only of supplemental interest that one of the spillways had a slope that approached 30 percent. This citation would have been moot with a more exact replication of the Pennsylvania spillway design. As an alternative to continuing the geotextile to the inside face of the berm an equivalent to the earthen plug of the Pennsylvania embankment could be constructed from compacted shale. This would also probably eliminate the need for gravel or riprap on the crest/in the throat of the spillway. Without further research (perhaps contacting the engineers) it cannot be stated that the example provided of the use in Massachusetts dam remediation of the PAP -0790 method would have used only a geotextile filter had the initial design using a 2HAV been satisfactory from the point of riprap thickness and sizing. I included it primarily as an example of the actual use of the PAP -0790 method in a situation with downstream human risk. Although it also does provide an example of the use of a primary geotextile filter (albeit at 4h:1 V) in those circumstances. As a final note, while the use of the non - standard spillway design is adding time to the review, I am on a fixed price contract and the client is not paying for this (the final portion of the consulting fee will actually be paid on approval of the permit). Sincerely -