The URL can be used to link to this page

Home My WebLink About20111013 Ver 1_More Info Letter_20120117A�� h C®ENR North Carolina Department of Environment and Natural Resources Division of Water Quality Beverly Eaves Perdue Charles Wakild P E Dee Freeman Governor Director Secretary January 17 2012 DWQ Project # 11 1013 Beaufort/Craven Counties CERTIFIED MAIL RETURN RECEIPT REQUESTED Mr Thomas Steffens Acting Field Chief U S Army Corps of Engineers Washington Regulatory Field Office 2407 West Fifth Street Washington NC 27889 Subject Property Martin Marietta Materials — Vanceboro Site Dear Mr Steffens On behalf of the NC DWQ Wetlands Buffers Stormwater Compliance and Permitting (Webscape) Unit we respectfully request that you consider the following comments within your review of the 404 Individual Permit request for the above referenced property 1) The applicant has acknowledged that other sites were evaluated in the alternatives analysis and this information was shared with the USACE This Office would like comment from the USACE regarding the results of this analysis 2) In addition to the aquatic habitat assessment of the upper headwaters of Blounts Creek that was authorized by the applicant this Office recommends a modeling exercise to evaluate the effect of the mining process wastewater discharge on the biochemistry of the receiving waters (an unnamed tributary of Blounts Creek) Because of the proximity of the proposed mine to estuarine waters dilution of those waters from the proposed mining discharge could be problematic Additionally monitoring of the Blounts Creek will likely be a condition of any permit Finally it should be noted that the surface water classification of Blounts Creek is SB (salt waters with primary recreation) and NSW (nutrient sensitive waters) 3) This Office requests that the applicant please re submit your site plans on full plan sheets at a scale of no smaller than 1 =50 with topographic contours shown 4) This Office requests that the applicant please locate all isolated or non isolated wetlands streams and other waters of the State as overlays on the site plan 5) This Office requests that the applicant please locate all of the protected riparian buffers as overlays on the site plan clearly showing Zone 1 and Zone 2 6) This Office requests that the applicant please provide cross section details showing the provisions for aquatic life passage Wetlands Buffers Stormwater Compliance and Permitting (Webscape) Unit 1650 Mad Service Center Raleigh North Carolina 27699 1650 Phone 919 -807 63001 FAX 919 -807 6494 Internet http //portal ncdenr org /web /wq /ws An Equal Opportunity 1 Affirmative Action Employer Martin Marietta Material — Vanceboro Site Page 2 of 5 January 17 2012 7) This Office requests that the applicant please indicate all wetland impacts including fill slopes on the site plan 8) This Office requests that the applicant please provide a qualitative indirect and cumulative impact analysis for the protect Please see DWQ s policy for guidance on our website at http / /portal ncdenr orgLweb/wq/sytp/ws/40l/policies 9) The following comments and questions were submitted to DWQ on behalf the Pamlico Tar River Foundation a) Concerns regarding the CZR habitat assessment i) Have you all had conversations with the company regarding the pH of the discharge water? Blounts creek is naturally 4 5 5 at most The NPDES application included quarry water discharge data and the pH was 7 4 (the source of the sample is not provided other than information that it is quarry discharge water of a similar mining operation ) ii) Comments from an ECU researcher Dr David Kimmel Assistant Professor of Biology East Carolina University (ECU) regarding habitat analysis (comments in italics) (1) What is largely missing is some context of these findings when compared to other similar streams This is particularly true for the fish The macro invertebrate data is compared to some state standards but the Biotic Integrity measures are often designed for a single system and broadly applied (2) Regarding the Jaccard index and the Monsita Horn indices Both are fairly standard techniques to measure similarity It might be useful to measure a stream that is similar but outside of the potential impact range to give a taste of what some of the differences outside of the system might be For example these systems may already be degraded in some way or may be exceptional habitat Usually the state has some definition of minimal quality in relation to some measurements (3) The lower natural pHfor coastal streams will often predispose the taxa towards lower diversity (4) With regards to this statement in the analysis The Jaccard index indicated that although UT2 had the most species in common with Blounts Creek ( 0 75) the Morisita Horn index indicated that UT2 was more similar to UT1 in terms of community overlap (0 79) (Table 4) on page 8 These comparisons are probably meaningless unless compared to some known distribution or diversity of these streams (5) With regards to the statement in 4 2 fish in page 14 Overall both species richness and total abundance were relatively low for both impact and control monitoring locations Compared to what? It is unclear here what is meant by low it has to be qualified by comparison to some standard or other stream These numbers may appear low but may be natural for these systems Also the fish numbers reported are absolute numbers and do not incorporate the effort it took to collect them For example you could collect 9 fish in a few minutes in a healthy Martin Marietta Material — Vanceboro Site Page 3 of 5 January 17 2012 system and collected the same amount over 5 days in an impacted system Need some CPUE analysis iii) Additional concerns (1) 1 day of sampling does not provide sufficient information on downstream impacts In personal communication with Dr Anthony Overton ECU sampling for young of year was conducted too early and should have been conducted in June or July (2) Seasonal sampling required (3) Little to no analysis on downstream impacts from dewatering discharge re flow chemical changes salinity etc b) Concerns regarding hydraulic assessment of receiving streams i) These concerns are focused on the discharge point and impacts downstream to the UTs and Blounts creek (1) From Dr Scott Lecce Associate Professor of Geography ECU (a) For 3 of the 4 channels the addition of the 18 6 cfs would produce flows that equal or exceed the bankfull discharge which could lead to channel instability in the form of widening or incision This could produce knickpoints that migrate upstream Although the stream power and shear stress values estimated in their scenarios appear to be fairly low I would also be concerned that substantially increasing the discharges experienced by these streams even to flows less than bankfull have the potential to produce channel adjustments I assume these elevated discharges would be experienced continuously and this could impact vegetation and the stability of channel banks Bankfull flows normally experienced by these streams may occur several times each year but only for a few days in duration not continuously throughout the year The report also does not comment on what happens during storm events when stormflow is also conveyed by the channel in addition to baseflow and the 18 6 cfs9 I assume there would be some restriction on discharging the 18 6 cfs during such periods (2) From Dr Mike O Driscoll Associate Professor of Hydrogeology and Environmental Geology ECU (a) What could happen if the UT2 segments were to receive too much discharge9 They may respond by widening and deepening (especially if new sediment inputs do not increase with the discharge increases) Usually if the deepening occurs then the slope will increase and a knickpoint will develop that would result in erosion that occurs and the knickpoint would migrate upstream ,lust like a waterfall moves upstream over geologic time This has happened a bit in Greenville where stormwater outfalls have deepened and widened some channels Some of the literature seems to suggest that these disturbances may take a long time to work through the system and so it could be decades before the stream channel and its sediment and discharge regime re equilibrate Martin Marietta Material — Vanceboro Site Page 4 of 5 January 17 2012 (b) One thing that is a bit inaccurate in the report is that they say bankfull flooding should occur around every 1 1 13 years Those numbers are for streams in Piedmont and Mountain settings and are too high for the Coastal Plain There is a paper by Sweet and Geratz where they state that bankfull flooding for similar NC Coastal Plain streams occurs several times a year Also if streams are channelized they may be able to handle more water than a similar natural channel but this might put the stream segments further downstream at a greater flood risk since the floodplain is not really functioning along the channelized reaches If channels are channelized they may have steeper banks than is normal and if greater discharge is added those banks may have a tendency to slump and the bank material may add sediment to downstream segments (c) Additional concerns (i) There is no mention in the application how downstream stability is to be monitored or what corrective actions would take place should erosion and sedimentation occur if permitted (ii) Will a control creek be utilized for monitoring? (iii) No mention of bank stability downstream impacts water quality standards during storm events and normal bankfull flows and the added discharge c) Impacts to WQ standards and downstream habitat i) Impacts of FW discharge and flow changes to brackish system and aquatic habitat Not evaluated u) Impacts of combined groundwater /stormwater discharge including turbidity TSS pH changes metals other pollutants Not evaluated iii) Martin Marietta s analysis fails to evaluate impacts beyond the creek s headwaters iv) What is the design of the treatment systems? v) If permitted how does Martin Marietta plan to mitigate for habitat loss and the loss of other existing uses? d) Alternatives i) As we know the requirement is to avoid then minimize Avoidance and minimization must also include the downstream impacts due to the mine dewatering discharge ii) Alternative analysis should include avoidance or minimization of the discharge via possible alternatives that may include (1) Depressurization wells that could then re inject all or a portion of the groundwater to avoid or minimize impacts via wastewater discharge and groundwater withdrawal and drawdown (impacting adjacent private wells and water supply"is would have to be Martin Marietta Material — Vanceboro Site Page 5 of 5 January 17 2012 wells of only Castle Hayne water as injection of wastewater is not allowable under NC rules and statutes This would be an alternative to pumping from the open mine pit (a) This should have been included as well in their engineering analysis for the NPDES permit application which it was not (2) Connection to local water supply (3) Other alternatives that would avoid or minimize the discharge of wastewater to Blounts Creek (or other creek systems) Thank you for your attention If you have any questions please contact Ian McMillan or me at (919) 807 6300 Sincerely �,W7� "*2� Karen Higgins Wetland ers Stormwater — Compliance and Permitting Unit Supervisor KAH/ijm cc William Wescott U S Army Corps of Engineers Amy Adams DWQ Washington Regional Office Susan Massengale DWQ PIO Melba McGee DENR Chad Evenhouse Kimley Horn &Associates Inc Tom Reeder DWR Tom Belnick DWQ Washington Regulatory Field Office 3001 Weston Parkway Cary NC 27513 Becky Fox 1307 Firefly Road Whittier NC 28789 File Copy Filename 11I013MartmManettaMatenalsVanceboroSite( Beaufort_Craven)IP_Commentmg_Letter USACE