REV99753

• Permit No: C1981041
• IBM Index Class Name: Revision
• Doc Date: 4/29/1997
• Doc Name: PR-02 ADEQUACY REVIEW ROADSIDE PORTALS C-81-041
• From: DMG
• To: POWDERHORN COAL CO
• Type & Sequence: PR2
• Media Type: D
• Archive: No

diversion ditch. Why has this culvert been removed from Map 8B and
pages RSN-41 through 43?
91. Powderhorn directed the Division to page RSN-40 for designs of the
36" flume at the outlet of the East Diversion Ditch. Page RSN-40
are designs for the Cameo West Diversion Ditch. The designs noted
by Powderhorn do not appear to be applicable to the original
question. Please submit a design for this 36" flume.
94. Powderhorn states that both culverts are shown on the south end of
the refuse pile on Exhibit 6B. Exhibit 6B depicts all of the runoff
entering only one of the 8" culverts. Page RSS-20 states that the
excess flow will be carried in 131 culvert. The Division is unclear
as to how this excess flow will be carried in the S" culvert on the
south end of the refuse pile. Please inform the Division how the
excess flow will reach the south 8" culvert and revise the permit
pages and maps accordingly.
95. The operator provided designs for a 100-year diversion above the
roadside refuse pile along Light use Road 1. The operator is
reminded that, pursuant to Rule 4.05.4(2), the 100-year diversion
will need to be certified upon its completion. In the interim
period prior to construction of the new 100 year diversion channel,
the south diversion ditch will continue to function as the upper
diversion for the Roadside Refuse Pile. As such, the south
diversion ditch will need to be certified as complying with
applicable requirements, pursuant to Rule 4.09.2(7) and 4.05.4(2).
As you are aware, there is no upland diversion ditch specified in
the permit for the operational phase of CRDA #1. Apparently, this
variance from the requirement of Rule 4.09.2(7) was originally
approved by the Division in light of the extreme slopes above the
refuse area, and the relatively small acreage between the refuse and
the upper boundary of the drainage basin. Language justifying the
variance, including original design considerations and operational
history, should be included in the amended permit application.
96. Powderhorn did not adequately address this question. The Division
is aware that these are after the fact designs, but they still need
to meet the performance standards. According to the book titled,
Design Hydrology and Sedimentoloay for Small Catchments by C.T.
Haan, G.J. Barfield and J.C. Hayes, it is stated that a critical
headwater height equal to 1.5 times the culvert height is reasonable
for the entrance of an ordinary culvert. Please justify the 2' to
lo' headwater height used in the culvert/pipe designs leading to
Ponds 8 and 9.
97. Same question as 94.
98. The operator states that Exhibit 19 was not submitted as part of the
permit revision, and it is covered by an old certification. Exhibit
19 should reference the location of the P.E. certification.
100. The operator revised page 13-16 and Exhibit 55 to clarify the rip