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Home My WebLink About20140957 Ver 2_Water Withdraw Info_20170717Burdette, Jennifer a From: Tarver, Fred Sent: Monday, July 17, 2017 4:54 PM To: Burdette, Jennifer a Subject: RE: Atlantic Coast Pipeline Jennifer, I don't have a great deal of concern over the amount as long as they maintain flow -by. Most of the year it shouldn't be a problem. The impingement/entrainment issue may be a concern given the time of year, size of pipe, pump and screen spacing. Since the gage is close -by in Contentnea Creek, it will be easy to monitor flows, however, on the Tar they may need a temporary gage. Let me know if you have additional questions. Fred Regarding the pumping rate, the following is from a WRC document: "For projects without diadromous species, our standard recommendation is for trashrack spacing not to exceed 2.5 inches and intake velocities not to exceed 1.5 feet per second. If upstream passage of diadromous fish is required by a FERC license, it would be necessary to investigate design and operation measures to safely pass these species downstream." The velocity of 500 gpm depends on size of orifice and pull of pump. From my comments on the DEIS: "DWR recommends that, irrespective of timing and location, water withdrawals from all surface waters occur in such a manner that 85 percent of flow is maintained downstream of the point of withdrawal at all times, with the exception that withdrawals cease when a downstream flow equivalent to the 20 percentile (i.e., 80 percent of flows exceed) cannot be maintained. For ungauged locations, the applicant should establish temporary, rated staff gauges to determine in -flow." 500 gpm = 1.11 cfs 1.11 cfs = 15% of 7.4 cfs. The site on Tar River = —682 mit. At 500 gpm, acquiring 1,281,000 gallons would take 2562 minutes or 1.77 days. The upstream USGS gage is at Tar River, w/ a drainage area of 167 mit. Rationing the 7Q10 value of 0.19 cfs down to the site gives a very rough approximation of 0.75 cfs. The 7.4 cfs flow would roughly equal 30 cfs at the site. The 80% Exceedance Probability =— 32 cfs (8 cfs ratioed down from gage site.) There again they would be maintaining more than 85% flow -by before having to cease at 32 cfs, although the margin is a bit closer. The site on Contentnea Creek =-162 mit. At 500 gpm, acquiring 1,122,000 gallons would take 2244 minutes or 1.53 days. There is an active USGS gage between Buckhorn Reservoir and Hwy. 581, which is just upstream of the x-ing. September & October are the driest months with 7.4 cfs laying between the 80 and 90 % exceedance, i.e., 80 to 90% of flows > 7.4 cfs. 19 cfs = 80% Exceedance Probability. Because 7.4 cfs is less than 19 cfs, they would be maintaining much more than 85% flow -by before they cease pumping at 19 cfs. The Water Year (WY, Oct to Sept) 7Q10 = 0.4 cfs, which is less than the 99% Exceedance of 0.96 cfs, i.e., >99% of flows > 0.4 cfs. As you can see 7Q10 is not an adequate flow -by.... Fred RTarver III Division of Water Resources NC Department of Environmental Quality 1611 Mail Service Center Raleigh. NC 27699-1611 Email: fred.tarver@ncdenr.gov Phone: 919-707-9029 Fax: 919-733-3558 (E-mail correspondence to and from this address may be subject to the North Carolina Public Records Law and disclosed to third parties.) From: Burdette, Jennifer a Sent: Monday, July 17, 2017 8:10 AM To: Tarver, Fred <fred.tarver@ncdenr.gov> Subject: Atlantic Coast Pipeline Fred, Would you please review the proposed water withdrawals from the Tar River and Contentnea Creek shown below and let me know if you have any concerns about the amount or rate of withdraw? ..�tlttridfee / ]r'fer P,Vh aah°wsvidondNrarp Rcxw'v f'xr3a'drsrr.e'Jgn:'e rTcw r_. ell 11.1"N? (`r vseo qY fiwdw e�dooarre (;'sxAr PjimVive nt :Vorrh ('cwr',)Jai A11- swic'( 2 1drretrpnid `rararentorcrrr Cyve.k 5 6 I, i _ wo 6 7. 109 5� Thanks, Jennifer Jennifer Burdette 401/Buffer Coordinator Division of Water Resources - 401 & Buffer Permitting Branch Department of Environmental Quality 919 807 6364 office iennifer.burdettep_ncdenr.gov 1617 Mail Service Center Raleigh, NC 27699-1617 (Physical Address: 512 N. Salisbury St, Raleigh, NC 27604 - 9t" Flr Archdale Bldg — Room 942F) Eblrttdoled Ir'rdler `-.4ltrddli?u'/ U'ut r, I fr't_nj JVd l/ 'Jd rar•a al, r efaia � rd8c^r ark' �c`'S./ hP- 1""son? 111'r/r`rt 11Prtt3f± 1 N 1d�I m�lddNl °`ce'��>tNNvoil i`,�rt�r/Im.m .r Y ) Fy P u "r KID KID 1r' 'room la ) l"61nit. dr,$"xw"A' d"4"aAl# r(", ,�8'dnh' .trr$ti"'P q � nd,d hypt S`d gG �Y�a idl. 7dd iJd+ °J1'-2 swutotl PereddNnal 1rNt"° Rt%vr 59A 1� � 0iIR')() 7600 b ) A11- swic'( 2 1drretrpnid `rararentorcrrr Cyve.k 5 6 I, i _ wo 6 7. 109 5� Thanks, Jennifer Jennifer Burdette 401/Buffer Coordinator Division of Water Resources - 401 & Buffer Permitting Branch Department of Environmental Quality 919 807 6364 office iennifer.burdettep_ncdenr.gov 1617 Mail Service Center Raleigh, NC 27699-1617 (Physical Address: 512 N. Salisbury St, Raleigh, NC 27604 - 9t" Flr Archdale Bldg — Room 942F) Email corresponclence to and fi`om thlois address is sut-yect to tlhe Alotill-I Carolina Public Records 'Law and may be disclosed to thloird patlies,