From: Dionne Filiatrault [srtech@nwb.nunavut.ca] Sent: Tuesday, November 16, 2004 9:44 AM To: 'Phyllis Beaulieu'; Steve Lines (Steve Lines); 'David Hohnstein' Subject: FW: RE: Bennett Additional Questions Ftp site, additional info. ____________________________ Dionne Filiatrault Manager Technical Services NWB & NIRB PO Box 119 Gjoa Haven, NU X0B 1J0 Tel: 867-360-6338 Fax: 867-360-6369 email: srtech@nwb.nunavut.ca -----Original Message----- From: Pete McCreath [mailto:pmccreath@shaw.ca] Sent: Thursday, November 11, 2004 9:18 PM To: Kelly Sexsmith Cc: bbennett@acres.com; missal@tahera.com; srtech@nwb.nunavut.ca; Bruce Ott Subject: Re: RE: Bennett Additional Questions Kelly, Bruce et al, Apologies for not responding sooner - email connectivity here (Tanzania) tends to be a bit erratic !) Regarding Q3 first part - "It is our understanding that the Area Concentration values in Table W3 assumed that the footprint of a particular dump or stockpile was in place at the onset of the project and, therefore as a result of this assumption, provided worst case values throughout the Operational Period of the project. Is there any information to show an estimate of the Area Concentration values (and the end result on effluent concentrations in the PKCA) at a time near the beginning of the project (for example at the end of the 2007 season) to illustrate the concentration differences that would be expected to occur at the onset of the project compared to the assumed worst case situation at the end of project?" ===> This information was included in the file "PKCA Concentration Sensitivity to Pond Discharges" prepared on November 11, 2004 - Kelly, can you forward a copy to Bruce? Question Q3 second part - "We would expect that if a Component Area leached higher than expected contaminant concentrations for a particular parameter which, in turn, led to higher than expected concentrations in the PKCA effluent, then this situation would not occur until near the end of the operational period of the project. Could you please confirm that the PKCA would have sufficient capacity to store all site area runoff without any releases for a sufficient period of time near the end of the project (to enable the particular contingency measure to be implemented) as opposed to the "first two years of operations" as per page 15 of Technical Memorandum W. If treatment of a particular parameter was found to be necessary, then we would expect that this situation would not manifest itself at the beginning of the project but rather near the end of the project." ===> Confirmed that the PKCA has "sufficient capacity to store all site area runoff without any releases for a sufficient period of time near the end of the project". Rationale follows (all references to Tech Memo W. Figure W7 shows the pond at elevation 518.3m in Year 5. Figure W3 shows a volume of approx 1.19 Mm3 available between 518.3 m and the spillway at 523 m. Table W4 shows the annual total inflow (all areas - PKCA, Areas A, B, C and Pit) equals about 490,000 m3...therefore, at Year 5 there would still be enough storage for about 2.5 years of inflows from all areas. After Year 7 the pit would be available. Question Q4 - "Page 14 of Technical Memorandum W states that the ".maximum proposed release rates [from the PKCA into Stream C3] are less than the 5 year to 10 year return period estimated flood flows." and ".additional overbank flooding or local erosion due to the proposed PKCA releases are, therefore expected to minimal or non-existent". Please confirm the basis for this conclusion since one might typically assume that the normal bankfull capacity of a stream channel corresponds to a 2 year return period flow rate. This would suggest that 'out of bank' flows and potential streambank erosion may occur in Stream C3 for the proposed PKCA releases. Was the bankfull capacity of the existing Stream C3 channel determined in the field or estimated using hydraulic calculations in order to support the latter conclusion?" ===> This question was addressed several times during the Tech Meetings. In short the C3 channel will be inspected prior to any releases and if areas subject to excesseive erosion are identified remedial steps will be taken (add gravel or riprap protection). Again apologies for the tardy reply. Hope this helps. I will be back in regular email contact on about November 23. Regards Peter S. McCreath Clearwater Consultants Ltd. (604-534-2411) ----- Original Message ----- From: Kelly Sexsmith Date: Wednesday, November 10, 2004 5:56 pm Subject: RE: Bennett Additional Questions > Bruce, > > > > For clarity, I have provided brief written responses to the items we > discussed earlier today, as follows: > > > > Q1 > > Although Table W2 shows the monthly water balance volumes to and from > the PKCA, including storage changes, Table W3 does not show the > outflowvolumes, contaminant concentrations or loads from the other > wastewaterstreams (as per Figure W1) entering the PKCA. Is there > a summary table > of the PKCA contaminant load balance for Total Copper and the other > contaminants of concern in another Technical Memorandum? > > > > Table W6 provides the concentrations from each of the collection ponds > and from the pit sump. Source concentrations for the inflows to > each of > these areas are provided in Technical Memorandum I of the Sept 2003 > submission. The entire sept 2003 submission was reissued as part > of the > water licence application as Appendix BB. If you require a copy > of TM-I > , please let me know. > > > > Inflows from individual sources to the ponds are proportional to the > areas shown in Table W1, part 8 (MAR x area). I believe these are > distributed according to the hydrograph shown in Part 2 of Table W1. > Fine PK supernatant inflows are assumed to come in at a constant rate. > > > > Q2 > > It is our understanding that Total Copper concentration values > shown for > each of the components (Areas A, B, C and the Pit Pond) were > derived as > an average from each of the contributing loads to that particular pit. > Hence the reason that the Area Concentration values in Table W3 > are less > than the corresponding Component Area Concentrations in Table W1. Is > there a summary table showing the individual loads and flow > volumes into > each Area which, in turn, shows the correlation between the Area > Concentration in Table W3 and the Component Area Concentration in > TableW1? > > > > There is no summary table. However, I believe with the > information from > above that you should be able to replicate the calculations. > > > > Q3 > > It is our understanding that the Area Concentration values in > Table W3 > assumed that the footprint of a particular dump or stockpile was in > place at the onset of the project and, therefore as a result of this > assumption, provided worst case values throughout the Operational > Periodof the project. Is there any information to show an > estimate of the > Area Concentration values (and the end result on effluent > concentrationsin the PKCA) at a time near the beginning of the > project (for example at > the end of the 2007 season) to illustrate the concentration > differencesthat would be expected to occur at the onset of the > project compared to > the assumed worst case situation at the end of project? > > > > We would expect that if a Component Area leached higher than expected > contaminant concentrations for a particular parameter which, in turn, > led to higher than expected concentrations in the PKCA effluent, then > this situation would not occur until near the end of the operational > period of the project. Could you please confirm that the PKCA would > have sufficient capacity to store all site area runoff without any > releases for a sufficient period of time near the end of the > project (to > enable the particular contingency measure to be implemented) as > opposedto the "first two years of operations" as per page 15 of > TechnicalMemorandum W. If treatment of a particular parameter was > found to be > necessary, then we would expect that this situation would not manifest > itself at the beginning of the project but rather near the end of the > project. > > > > My understanding is that the facility can hold 2 years worth of runoff > at any time during operations. Pete McCreath should be able to > confirmthis. A gradual build-up in concentrations should allow > Tahera ample > time to demonstrate contingencies should they be required in the > latterpart of the mine life. > > > > Q4 > > Page 14 of Technical Memorandum W states that the "...maximum proposed > release rates [from the PKCA into Stream C3] are less than the 5 > year to > 10 year return period estimated flood flows..." and "...additional > overbank flooding or local erosion due to the proposed PKCA releases > are, therefore expected to minimal or non-existent". Please > confirm the > basis for this conclusion since one might typically assume that the > normal bankfull capacity of a stream channel corresponds to a 2 year > return period flow rate. This would suggest that 'out of bank' flows > and potential streambank erosion may occur in Stream C3 for the > proposedPKCA releases. Was the bankfull capacity of the existing > Stream C3 > channel determined in the field or estimated using hydraulic > calculations in order to support the latter conclusion? > > > > This questions will need to be deferred until Pete is available to > address it. > > > > > > > > > > ________________________________ > > From: Bruce Ott [bruce.ott@amec.com] > Sent: Wednesday, November 10, 2004 2:43 PM > To: bbennett@acres.com > Cc: missal@tahera.com; Kelly Sexsmith; srtech@nwb.nunavut.ca > Subject: Bennett Additional Questions > > > > I understand from Kelly Sexsmith that Questions 1 through 4 have been > answered by SRK. The attached answers Q5. Our answer is in blue > font. > Kind regards > > Bruce Ott > Senior Environmental Scientist > AMEC Earth & Environmental > 2227 Douglas Road > Burnaby, B.C. V5C 5A9 > Tel. 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