NC0026271_Regional Office Historical File Pre 2018 (61)

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DIVISION OF ENVIRONMENTAL MANAGEMENT
December 19, 1995
I ErqV,l.C. DETT Cyr
Rol, 1Ilgp-
MEMORANDUMA. up`�L rsou c;'
To: Todd St. John 91V
15, t 17fJ
Mooresville Regional Office
From: Greg Nizich 612
NPDES Permits Unit
Subject: Aeration/Mixing Requirements
Authorization to Construct #AC0026271
Town of Taylorsville WWTP
Alexander County
I received your comments today for this ATC. I requested information about 2 weeks
ago on the aerator performance since I don't have experience reviewing these for aeration
basins. The attached pages are what I was sent. Despite several numerical errors, the
calculations seem to justify the units selected. If you know of any other parameters you
would like them to evaluate, or problems with these units in similar plants, let me know.
�eo 14, ull cf�
Attachment Y XX Z,
�("h rev ['eWip- 444('4
F6L l - z z ;5 file, &u, � �,
fit/ r el �� %. �/� /,L

12/0e/95 15:52 17044395962 WEST & ASSOCIATES
PAGE 91
JUN-06-96AERATORS
AERr l
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FAX ONLY
FAX NO. 704/433-6862 fltuls�cr� �F EI;Uf� i ,E;i;t iRP!�GEf;9Eia�
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Mr. Benjie Thomas AE2AT"iDN QE62U)2FMCt7_i S
Dear Mr.. Thom -Re!
`phis is -w cOnfirm our conversation today regarding an activated
el,udge proce4o for domeatie(75%) and ind%aetrXal,(250%) waclteHater
treatment. �
Our calaulationi� w determl,na the horeeapower for this
opplioation �.j based on the 2oljowing pargsletoVw,:
Ranin dir4enal,ana - 80 ft. diatmo-Wr► 10 feet deep
Avg. temperature, - 204 G
Altitude u 1200 ft above saa level
Daily wat4r £loci - 415,000 Rallona
Influent BOD5 - 450 inAfl
Ffiluont DOD5 - bU mg�l
1*H - Apprq'x; , 7.0
Thd assumptjoaa made to calculate Oe field tranafer rate of
a;cydoa Ore
Clean wa'L'eir transfer rate (CWTR) - 2.75 # caa jhp-hr
Alpha facior - .90
Beta f&Qtcxr .95
Roaldual d'imsolved ourg,an
ThQ formula four oalCalat,ing the fiol-d trppefer rate jai
L'TR CHTR, Li<<�L�s x uata)-L;jj) X (1.U2�)'f�,�Q] Alpha/$.17
i
The saturAted d6noentrption of diueolved gen at aq
d�itt^wr♦e C. nna at ar, alLludq vt i�U0 ZV, l,p ,.7 ux�►pgan
S�aL',;. ti Guting the abovo asat3mad valuea gives n FTR or 1. GDC0
pounda of axygon -per hora6vower--hour.
The formula u60 to 043.0410to thg BCD:, a4ded to the baai n eaQ1,
day io; i

12/09/95 15:54
170d4335662 .
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i'UF 12 - 62
AERATORS !NC
FAX NO. 8166236418
0.415 '4500)g/.L
Pounrie Of BODS/daY = 8.34 x 0 x p x BoDf, = 1, 6 7 #I Ai
Ef F 30-83.3
12. _ /0-fi'/DA.�
where Gl waetewatar flown per day in -gallons r
P-a the percentage reduction U BOD6
BODE = the eongentration of ]QMs in mg/l
P. 02
Substituting the given values .in the, foxmu],a gives h value of
1419 # of BUDS por day added to the basin. The design 18 to
reduoe t1jia'4mQunt to 300 B0115 per daV disnhaxge in the offluent,
or a 93.3 Poraent reduction. This means that we mint remove $$3
:s 1419 mounds of PON pars day. Good praotiae is to apply 1.2
Pounds of o�Ygen per pound of BOD5 removed.
Pounds of oxygen to bQ added per day ie 1419 x 1.2 1703 #/day
= 71 #/hr
55"1 x I.Z = Ig68-"/bay
livrsepGw;or of aeratora requirad = 71 #41.r,,._
1.6.90 #/hp-hr
41.86 HP = us.,9 HP
Thro basin 'volum6 is 'Calculated to be 376,000 gallon$,
The activated kludge pxanaa- xrayui,xw;s that the ealide be kept in
8-uaPengion and to do t.hle requi.ree Approximately 11)0 hp per M►xiJ6
u,il"Qa gallons of WasteV&t6r voluwe . A -forty- hp aerator "would L O,P
provide a u,ixina intoneity of 107 hp per millions gall,Qns. - 101HP
A 40 h0r4epower aerator might very well do -this Joh if thfj actual,
Conditions are all favorable lar o; xgen tx.4Lnei,�,r. zf they are
not, then a 40 horsepowrax waulrl ba too - small.. To be orx the
conservative, lido, priors* rarer givr�n for a 50 tip aerator..
For aLa all GLal'nieFis steal, aerator, the Model, 1360-BV, the price
Is $20,000 and far a unit with epoxy cxoatod cast nickel -iron and
fiberglass Me oat, tho price ie $16,000. Therprices are
approximate,,
I Rope this gives You want yQu waAtad, if nQt, give me a call.
rinceralY,
Charles Cloorr,
co:laill Ward - lnterstato utility 6al�s�