ENFORCE20070

• Permit No: C1981019
• IBM Index Class Name: Enforcement
• Doc Date: 8/12/1993
• Doc Name: HYDROLOGICAL MODELLING CHRONOLOGY
• Violation No.: CV1993073
• Media Type: D
• Archive: No

April 14, 1992 - Colowyo submits supplemental information to MLRD regarding PR-1.
Included was a detailed curve number justification and agreement to
change from a "slow" to "medium" hydrograph response.
April 22, 1992 - Colowyo created and submitted supplemental Map 12A -Hydrology of
Gossazd and Mine Maintenance Areas, and submitted to MLRD.
April 28, 1992 - Colowyo submits a request for a Technical Revision (I'R} to allow the
building of the Prospect Pond. Timing has become critical for the
building of the pond and diversion ditch so that topsoil can be stripped and
mining of Section 16 can commence without any further delay. This TR
request was necessary because approval of Colowyo's Permit Application
• was still pending with MLRD.
May 10, 1992 - One yeaz anniversary of Colowyo's submittal to MLRD of the Permit
Renewal/Permit Revision Application. Approval by MLRD still pending.
May 19, 1992 - Colowyo receives an adequacy review letter from MLRD regarding the
Prospect watershed modelling. The Division has concerns regarding "the
appropriateness of the modelling assumptions used" and that "a clear
resolution of the questions regazding modelling assumptions needs to be
reached ...". Enclosed was an erroneous SEDCAD run for the Prospect
watershed performed by Kent Gorham, MLRD. This modelling showed
a total runoff volume ti a greater than the design submitted by
Colowyo May 10, 1991. Errors in MLRD's model can be readily pointed
out. Additionally it was stated "Use of the above model would a]so
possibly affect the sizing and channel protection needs of the diversion
routing runoff to the Prospect Pond." This diversion is the South
Collection Ditch.
May 22, 1992 - Colowyo meets with MLRD in Denver to discuss outstanding bonding and
hydrological concerns. From this meeting, the agreement is reached to
approve the Technical revision allowing the prospect Pond to be built with
the understanding that Colowyo and MLRD would jointly model and come
to agreement on the hydrological modelling of the Prospect watershed.
Steve Wathen, DMG, would be assigned to model the watershed with J.
Gazcia of Colowyo.
May 26, 1992 - MLRD formally approves Prospect Pond TR.
May 28, 1992 - Colowyo submits letter to MLRD formally explaining the agreement
reached to build the Prospect Pond and to come to a consensus on the
hydrological modelling. MLRD (Steve Wathen) ignores this letter
completely by providing no response or feedback.