-*-
 00 f
(V
ALTERNATIVE  CONVEYANCE SYSTEM REPORT

           VACUUM SYSTEMS
                                      RICH NARET
       CD
         HEADQUARTERS LIBRARY
         ENVIRONMENTAL PROTECTION AGENCY
         WASHINGTON, D.C. 20460

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          AI  iiiONAii'v'i  i :HNVI  T'AIJI :;   :;V:,IIM  i AI r.)
      IIVM-.'V(!W Hi  AI ll::h>MAM VI  i ;i INVI-YAWl'li:  SYl

      A.      I ntrndiu~:t"i on
      B
              1..  :'v i iiip'1 i t '"i e>d Syfii.t-ifi I)- ;f=:i ":' i pl. i> ' I i i :.< I, i i in-';
              :'<..  I- xt.c-'nl. n1  !ir--  in  (,|-i<-  II. :,.
              4   Myhh:'.  vr; RCM i i l.y
              !:i   i'M-.lii-r
      C.      Vacuum Systems

              1.  Histoi-y

                 a.   System Types
                 b.   System Comparison
                          Services
                          Collection Piping
                          Vacuum Station
                 c.   Summary

              2.  Simplified System Sketch

                 a.   Basic System  Sketch
                 b.   Components
                          Services
                          Collection Piping
                          Vacuum Station
                 c.   Operation

              3.  Potential Applications
              4.  Extent of Use in  the U. S.
              5.  Myths vs  Reality
                                                         /S/AZ.6T
1).
      SwK-ilH  i.)iiy:i by Si-.-wer;*

              1 .   ,l ,n rnp:i 3 f i ed f'-Jy F. ti=-m I J- -r-icr ipi. r.on
                  a.    Har-;i.i: f->ywt''|:Jfn 'ikft-.r.h
                  h..    r;rimponfvril".a
                  f..    ripp-r. =)!. inn
              ?.   Pnl-r-rih-i a") App I T f:at. i i >ru::
              I:l.   l-xt^nt. nt I lr-; in i.h<-' it  S.
              4..   Myhhw vs Uoril.it.y
F.    l :ompnr-i sson wi l.h  Cnnven 11 nn.< i  I :i  IJ <  :t.; i in  Sy-.-il..

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     I 'K'l SSI iK't  SI Wi
          SYS i i- MS HIIWNI
III.  VACUUM SEWER SYSTEMS
     A.

     B.

     C.
     D.
 Introduction

 System  Plan and Elevation Views

 Description of  All System Components

 1. Services
 2. Collection Piping
 3. Vacuum Station

 System  Design Considerations

 X. Hydraulics

   a.   Design Flows and Their Variabilities
          Average  Daily Flows
          Peak  Flows
          Design Flows

   h.   Minimum  Flow Velociti.es in Pipes
   c.   Applicable  Equations
          Static Losses
          Friction Losses

 2. Mains, Services,  and Building Sewers

   a.   Mains
          Geometry
          Pipe  Sizing
          Routing
          Trench Section
          Pipe  Materials

   b.   Services
          Geometry
          Pipe  Sizing
          Routing
          Trench Section
          Pipe  Materials

   c.   Building Sewer

3. Valve Pit Settings

   a.'   General
          Fiberglass Settings
          Concrete Settings

   b.  Appurtenances
          Anti-Flotation Collars

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4. Vacuum Valves

   a.  General
          Model 0
          Model S

   b.  Appurtenences
          External Breather
          Auxiliary Vent
          Cycle Counter

5, Division Valves and Cleanouts

   a.  Division Valves
   b.  Cleanouts

6. Odors and Corrosion

7. Vacuum Station Design

   a.  Component Sizing
          Vacuum Pump Sizing
          Discharge Pump Sizing
          Collection Tank Sizing
          Reservoir Tank Sizing
          System Pump-Down Time

   b-  Typical. Component Specifications
          Vacuum Pumps
          Discharge Pumps
          Vacuum Tanks
          Standby Generator
          Station Piping
          Motor Control Center
          Level, controls
          Telephone Dialer
          Vacuum Gauges
          Vacuum Recorder
          Sump Valve

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E.
Const-ruction Con si. derations
      1. Line Changes
      2. Grade Control
      3. Service Connect:! ons
      4. Equipment Substitutions
      5, Testing
         a.  General
         b.  Vacuum Station
         c.  Collection  Piping

      6. Past Construction Problems
F.     Operation and Maintenence  Considerations
         O&M Manual
         Staffing Requirements
         &.  General  Information
         b.  Operator Responsibility

         Operator Training
         Spare Parts  Inventory
         As-Built Drawings  and  Mapping
         Maintenance
         a.  Normal Maintenance
         b.  Preventive Maintenance
         c.  Emergency Maintenance
      7.  Record Keeping
      8.  Troubleshooting
      9.  Evaluation of Operating  Systems
         a.   Early Vacuum Systems
         b.   Recent Vacuum Systems
                General Information
                Design/Construction  Data
                Q&M Data
         c.   Summary
3.
4.
5.
6.
      10.
      Past Operating Problems

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     G.     System Casts

            1.  Construction  Costs
            2.  O&M Casts
               a.   Labor
               b.   Clerical
               c.   Power
               d.   Utilities
               e.   Transportation
               f.'  Supplies/Maintenance
               g.   Miscellaneous Expenses
               h.   Equipment Renewal & Replacement
               i.   Future  Service Connections

            3.  User Charges/Assessments
     H-     System Management  Considerations

            1.  Homeowner Responsibilities
            2.  Sewer Utility Responsibilities
            3.  Other Entd.ti.es
     :;MAI i  m AMI IIM i;kAvrr  ::Y:;;u M i
V.    HKSIliN i XAHPi I


     2.     Vacuum Sewer  System     *-
     ;<      MIIU-I i I  I )"i THin^tf'-r  l-if "(vi ty My

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                              Q_F	F_!_G_U_R_I_S_
Fig.

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ft ft ft ft i
* * * * ^
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.* Description Chapter Section
Li] jendahl -Electrol ux Vacuum System
Vacuum Toi let
Colt-Envirovac Vacuum System
AIRVAC Vacuum System
Major Components of a Vacuum Sewer System
Valve Pit/Sump Arrangement
Upgrade/Downgrade/Leve 1 Transport
Diagram of a Typical Vacuum Station
Early Design Concept-Reformer Pockets
Current Design Concept-Pipe Bore Not Sealed
Sample Gravity Sewer System
Vacuum Assisted Gravity Sewer
Basement/Valve Pit/Main Relationship
Typical Layout-Vacuum Sewer System
Water System/Vacuum System Similarities
Plan & Profile View-Typical Vacuum Line
Plan & Profile View-Typical Valve Pit
Auxiliary Vent Location
. Lift Detail
Line Diagram of a Typical Vacuum Station
Liquid Ring Vacuum Pump-Cross Section
Sliding Vane Vacuum Pump-Cross Section
AIRVAC Calculation Form
Static Loss Determination in a Lift
Spigot Adaptor Detail
Crossover Connection Detail
Typical Fiberglass Valve Pit Setting
Shallow Fiberglass Pit Arrangement
Typical Concrete Valve Pit Setting
Typical Concrete Buffer Tank
Typical Concrete Dual Buffer Tank
Anti-flotation Collar Detail
Model D Valve
Model S Valve
Early External Breather Detail
Alternative External Breather Det-eil
AIRVAC External Breather Detail
Auxiliary Vent Detail
Division Valve with Gauge Tap Detail
Access Point Detail
NPSHa Calculation Diagram w/Typical Values
Typical Elevations of Level Control Probes
I
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* * ft ft ft ft a
*******
Til
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t ft ft ft ft $ a|
A
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' * *" S 9 9 9
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30     Effect of Temperature Change on
              Vacuum Testing
IIT

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                      __L_I_S_T___Q_F___T_A_B_L_E_S.
Tablg_*  	;	Descrj.pt ion	
  1      Vacuum Collection System Parameters
  2      Vacuum Station Parameters
  3      Summary of System Types
  4      Conditions Conducive To Vacuum
                Sewer Selection
  5      Operating Vacuum System in The U.S.
***********s**s*sss*********s****s*******s**sx

  1      Recommended Lift Height.
  Main Line Design Parameters
  3      Guidlines for Determining Line Slopes
  4      Governing Distances for Slopes Between I.
  5      Maximum Flow for Various Pipe Sizes
  6      Maximum Number of Homes Served For
                Various Pipe Sizes
  7      Typical Requirements For Separation
                Of Sewer Lines From Water Lines
  8      Service Line Design Parameters
  9      Situations That Dictate The Use Of
                Concrete Valve Pit Settings
  10     Vacuum Station Design Nomenclature
  11     "A" Factor For Use In Vacuum Pump Sizing
  12     Discharge Pump NPSH  Calculation Nomenclature
  13     Typical Values For NPSH Calculations
  14     Values of Vo For A 1.5 Minute Cycle % Qmin
                For Different Peaking Factors
  15      Spare Parts List Per Every 50 Valves
  16      Specialty Tools And Equipment
                For Co3lection System
  17      Specialty Equipment For Vacuum Station
  18      Operating Systems Visited in 1.989
  19      General Information On Operating Systems
  20      Design/Construction Data-Collection System
  21      Design/Construction Data-Vacuum Station
  22      Operation 4. Maintenance Data-General Tnfo
  23      Operation &. Maintenance Data-ManKmirs/Year
  24      Operation fc. Maintenance Data-Power/Year
  25      Operation 4 Maintenance Data-MTBSC
  26      Classification  of Operating Problems

  27      Typical O&M Cost Components
  28      Manhour Estimating Factors
  29      Vacuum Station  Power Consumption
              Estimating Factors
  30      Typical  Renewal And Replacement Factors
  31      Annual Budget Example
Chapter
I
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Til
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ts ITT
TTT
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Til
TTT
TTT
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TTT
ure Til
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Til
III
TIT
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ITT
III
III
TTI
ITT
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TTT
Section
C
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t.   OVERVIEW OF ALTERNATIVE  CONVEYANCE  SYSTEMS




    C.   VACUUM SYSTEMS

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                                S E  C  T  I  I!)  N     C
                        .y_A_C_U_y_M	S_Y_S_!_E_M_S_
1..
n
          Vir  r:o I  I r-i :t."i nn  '.yr-tir-mn  WOKO  pat,nt.r.'ri in  t.h^




    t ln::i fr.r;d in  "t HMH,   whi-'n  Adrian  I .F; Mar1 qua rid  invt"-inl/->d  ;=i  system  'i1




    GRwage co I l.^cti.nn  h F t ?r:V.fn3 nx )   i.t'i r:ant,  i..ia 1=f'i=!K"Rnr:e flmnng  t;hKi=?  "in t.t^ffuss  of  design




    noncwpt.:^.    Th  major'  di 1;1-er-en(~F'r:;  1 i 1=?  .in  hhr-  xt.finfc t.o  w




    i.he  Kysl.enis  use   SHpar-aL*?  blar:k  ( t.oi ].rt. )  and  gray ( t,he  ba




    wat.f;?f  oo'l. Xpr:t.i on  man ns.    E I writ-K-n'] ux  ufseK .H :;vepaK'^t,i"-  system  t'-or




    t.hp?e  nouK'f.es ;  f-.nvi.K"ovrtr:  usi>;-:5  vfirsnurn  t.rn if-'f.R  nd on rn.iin;  <;inrJ




    ATFJVAi: and Var: O I er;  hnkc^ t,hi;i  ruiKmal   hi-iuKi-'--! u;> I  rJ noinhi nri




    w-Hf-;t'.es>.    Dt.hef  di 1:1"eKf=;n( :-;  KV- I .i1'.^  1,ri  hh  lnr:at/iori  ni~ i.h




    gravn by/ vacuum  .1 nt.ftrl^icR  ^nd  V.o  t.h-  di=?Fsi >.jn of- pump?:,  va I v-.-n,





    li.nRS,   etc.

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         The  t. i 1 Jendahl F l.ectro'l ux system war-:  fi r ~st  used in  the

    Bahamas  in  the  late 1.9BO" s  (Figure?  1J.   In thi r-; concept,

    separate black  and gray water r:nl!l.';cti on  mains  arf* MRecl.

    Blrink water refers tn  ti-ri.let w.Hfitr-JM and gray water T rin'l udwfs

    a III  nther  domestic: wiit-jti--;water.   Tho blru:k water T r? di sr:l"ia".3i-'d

    to on=c o1:  tho vacuum ma:ins  thrnuj^h  i:< vacuuid  toilet (Figure ^'}

    while th  gray  water enterr, the otl'ter through the ur.e <.it  a

    J3per:ia 11 y  designed vacuum valve..   The separate  vacuum main

    are connected to the vacuum station.   l-or  critically wate>

    r-short areas,  such as the Bahamas,  the reduction  in toilet

    wast i'1 water  volume war;  a definite t:actor in the  Fse3.ecti.nn  of

    vacuum transport.
 TRANSPORT POCKETS
 VACUUM PUMP 
 BLACK WATER
"COLLECTION TANK
                                             BLACK WATER
                                             VACUUM MAIN
              GRAY WATER      T  CRAY WATER VALVE
              COLLECTION TANK '	GRAY WATER VACUUM MAW
              TO TREATMENT FACOJT1ES
                                                                 BUFFER
                                                                 VOLUME
                                    FTl'ilJRF 1
                            i TI .TFNDAHt -i-i FT:TROI..MX
                             VAilltllM SFWFR SYSTFM

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        VACUUM TOILET
                                                   JL
                                                         .FLUSHING
                                                         MECHANISM^
                                                       --VACUUM
                                                       |  MAIN
                           DISCHARGE VALVE
                             FIGURF ?
                          VACUUM Trm.F'1
    A  VacQTec system,  serving the I ake of the- Woods


development near Frederickssburfl,  Va.  was the first resident.-Lai


vacuum collection system in the United States.    This syst-.em


uses r:onoepts  of the L13 jendahl system hut has many Important


d"i Inferences.   The Vac.0Tec system requires no i nsa.de vacuum


ho.i 1 ets or vacuum plumbing.   This system employs a single


combined black and gray  water collection main.   large? (750


gaJ. )  storage  tanks are  required at each residence.   Finally,


an external power source is required for each valve since they


are electrically operated.   In addition to the i ake of the


Woods  system,   several  other Vac- Q-Tec residential systems-; h.ivf


been used by private developers.

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              The Colt.Fnvi.rovac  system  Is  the direct descendant of the


         l.i.1 Jendah'l-Fleotrolux f>yr-:tem (Figure 3)-   The Holt,  system at


         South Seas Plantation near Fort- Meyers, F1_a.  serves '.-in


         r err! derices..  The  houses  have separate blank and gray water


         pj umb ing.,   Ihe black water piping fVorn  the vacuum trn'iet jcnru


         the  yray water vacuum piping i.mmedi.i:ite!J.y  dowru:l.rearn nf the


         gray water valve.   A si.ngle pipe  with the combined  oontent?;


         transports the wastewater to the  vacuum station.
 GRAY
WATER-
VALVE
                                      COLLECTION TANK-
 TRANSPORT POCKET

VACUUM MAIN
                               TO TREATMENT^
                               FAOUTIES
                                        I (GURK  :-.<
                                    t;rii.T-4:Nv.runvAC:
                                 VACUUM ^hWFW  SYfJTFM

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     ATRVAC markets  & pneumatics 1.1 y  controlled and operated


vacuum valve which  is used  for cornbi ne*d gray  =tnd hi ack water


systems  (Fi.gurr-- 4).   The AIRVAC syntern a I "I own foe use of


con van hi cm a 1 plumbing in the house,  w:i t-.h the  wciKbewater


f"J owina by  9K~avi hy  to a i":arnhn nd sump/valve pit.   Thw valve


starts its  cycle when it senses approximately 10 ga.llonra has


accumulated in the  sump.   It apr-.*nr--  f'ar a few  secondK,  which i R


enough to evacuate  the contents of  thw sump ats we I..I  as allow


atrnospherd.c air to  enter t.h system.   The sewayR/a i r n xturo


      travels to the vacuum  station.


     AIRVAC' s f::i rr;t  system was inntallwd -in Mathwws r;ourthous4,


     :i n 1970.   Since then AU3VAC \-\HK  more than 30 add i t:i ona 1


      m operating i.n the United Stater-; with many more cui-rent'l y


being planned,  designed, or in oririKtruction..   ATRVAH has also


been  very active in the foreign market with apeati.ng systems


in Australia,  Canada,. Japan,  Holland,  and some other Furopeem


Countri es.
                                               VACUUM PUMP

                                           RESERVE TANK	

                                      COUECnON TANK	1
     VACUUM
     VALVE
TRANSPORT POCKET


VACUUM MAM
SEMMGE PUMP

TO TREWVEKT
FACUflES
                                F TGI IRl- 4

                                 ATRVAH

                         VAt'UIUM SFWI-IV SYSTEM

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              '"'    -..'y*^ ''.'''  ' 'OUILid.C!! f"H
                    Fach  nl::  t,h=  'four  s;yr?1",=?ms  have-  unique? d^wi ctn  fi:.-iil.urr':~.,     The
               I he* wahor  navi ng  tV-viiMi re-*  ol   t.ht*  I ..... I r*cLrpri I ux .-*'  at-; mur;h  a'.-\ 'S'f  p^ri'i^nt.  inf;  t.hft  hnLa I   in  .1

              ilninh  l,l'n-'  L.U::P'  <")i  v.inuum  t.n~i It ).---..      A 1 IV'v'Ai ;

              uid Van -U - Tpr:  Kystenis c..:an hr~>  .-i I Lf'>t-(-.>i1  t'-O  ;-n:r:
                                                                                          Blank:  1  1./5?"
                                                                                          &  'S" ;   ;^r ay ::   1-' "
                                                                                          A  :r-;   pvr: r,!
Single  iiu-rin.,   '.-I
4",  &  R" :  I'Vi:..
f special  "')"
Si.ns'l  tna'in,
A " -  PVi ;
                       Con ven tiorii-^"I    Pnwuma t,i i"
                       pi ijriih.ln3         va'l vn
                                                                 Set  cnn-Pi ;;|         Singift  main,
                                                                 urahion  wi t.h      ^ ",'"'",   &  "'" '
                                                                 pr-ol-.i U-              PVi:,   r-:cil v,^r.!.
                                                                                         wr- I H  CM--  "II"
                                                                                         t' i rig

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       Var:uum  va I V^K  ap<-jK4t;e  .:i.i1.nrn.-i Line I "I y.,   b;:t';;(.!  on  l.bf




    l uftH-f  Ot"  b"lfn:k  fit"  iSK'i-iy  writer   bwlrind  t,bt---  v,-Tiv<:>.    Prciv i rii-ij




 t.hrtt.  ;-;u1-1:"i rri.;>nl,  V.K:UUKI  i ;;  available;  in  t.ht   tii.im.,   t,br-  v.ilvor.




 wl I I   ripen  a1"t.p?r  ,-i  pn^dei'.^K'ftri nr*rl  vnlunif  i>f WMr.V.w,.|t,(.-K"i~.:ii .i;j  v.i I v*7'  .-if-rn-mlri j..y




 is  unique  in  t;h.it.  it.  r-eqij-t I'rtf;   an  f-fxt-i^rna !  r-''W^K   HH  t-h*-'  Vrn.niiin




f-:t..af,i  on  t.l-irrui'.^h  an exl-rvn  f-;oti  rrf"  r:rmt..--ic:t'.<;  in  t.hi-j




COnt.K'oX 1 er..     A  raeparat.o  r:yc: I i n;^  nindr-f,   r:.-n'll  i:oitmi. md




fVorn   ear:l't  v.'il. ve,,   i^nd  r-subsequent. I y  opr"rit,*=R  . ir.b  va.l v-




durin<3  t ow-f i nw  pK-i.ndf5.    1 hi.s f "l.t-.-x i bi 1 t.y ,iliow  t.l-ir;  --.vnl-.Rui




t.r>  st.OKe  Plows  dtJK'i ng  p><=?ak  pofi nds  .-^nd K"f-1 -'>i={3w  t.hern  l,ril.i;;K




during  1 nw  fJriw  p^rindr..    All   of   th->  ot.hfti-  r3ysV.eMn  inust. br-




deignftd  t.n  handli? pi^.nk   l^li'iws.     Tbi ?-;  -fi^FifcuKM.   drir-'r-;  howi;vi-<> ,




add cost.s  tin  t>in  b.ir-se  sysit.om.     AT r;rt,   addi. t.'iinn I  npr.Hl. i n;4




and skilled  F>J.rM-:t.ri::ini r:   t-er:bm dans ftfft  rfM'J i rt*ei  t.n




man nt.-i n  t.he  moc'i^  complex  syt;t,trir-5
                                         V

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       Of?!pt:~;nd'j riot  on  t;l">6"  iiitHnij'I'-n^l-i.it't'r,   hl'ir-  .-unourit.  iff  w^il.i-^K"




>-"*n te?""i nj}  tJ-n=  system  w t t'-l'i  I=>FI <:((  va t vi-.-  OPI---K ;-rl, i on  WIK~I <->K,     !





vacuum  V.ri'i. I ei".  *<"hn i  i,t~,  af'r>(r'c''x ' i(ii;it,t'j I y  (')_ H  ho  O.  4  cir3  Inn:-;  Fn-




t  I i.i:'2l i,   wi'i^fea;-:  t.hit-  pi ii-'ijiru-it. i i:. i I  ly   r:ri i l.r ri I 1 (-'d  vacuum  v.tiv<>





rtditn t.  10  to  1 Fi  yi I  Ion:1,  pwr  i.yiilr-.





       II.  S.   NiiVy  r f--Si--.'.;'U'i :l'i  hrt:.  r fpoKhrjd  l,!-i.-iL  -iood  1".K  inspi H- !.





i-:l'u-ir ;-n':t.i~'K "r..'> I. i CM  .-ire--  -f-ound  wil.ii  : :.i it -fri <: i f>n I.   inli-'t.  .H  i r   .-mo





fsma'i I   p-nouqh  -:'). 149  1 o-iHini-i:".  "tor  l.l'n=  ,-ivH'i I fibll.i-''  pfi->r-:KiJp-^





di.t-f'eKent'i *1  tn  nvi-'i-'nriiw*  hi K--   I iQU'id*:-:  'i nr-r h:i a .     fl-ii <:





KISCJU I ts  "in  fapi i;1  r-ilii;^  t>ri-Nv)k





quir:k"ly  at,  up:-;hrt-!.un  valvt-r:.

-------
                                      HOI  \Jf'.\ lllIM  PJI
       P i p~i ric) prrit'i I FJP:  d'i 1 f'f-'f,   nf-jpi-'nrli.ng  i in  upl ri  II,  rlriwnhvi  I I  ,   S3 gn




 rn.Hnua [   wh'i nh   i hT-.CK i bier-  l.l'n-  di--r. i t"^d  p-i.pin--j  prot'i'1 p-r.  in rj^oh




 s'i l.u.i I,'I>n..




       I herf'   l'u:iv(-!   br'i-.'n  t.wn  <'^'i f 1'i^ff-M-i I.  ccinr-.^pt.w  usr-rJ  in  v/rtc




 dt->f>:i 'jri.    Jn  t.|-ii->   1"i (;>!,  r:rmr:r^pt,   V.l"i-'  hriri"' ci1"  t,hu^  pipi-v  :i ;;




 r-.Ha"U-'d  during  r;1,aivi<::  ccmdi V.i < ms.    "I h.i r~ ir.  .n .-< 'impli <;hf--< I  t.hr nugh




 hhc iu~r>  rrl'  i-t=-^nrmr  prickfahf?.     1 ri t,hi-'  (it.l'iwK  r':onr:t'p1,,   Lhrt  b'nKR  of




 t.l'H--.' f. i i pe  i f. r\>\(\  PUSH | r-d.     Thr.;i grierJ  ijrm ng





bht-'f  lat.ter  pr::i riiri pl.e-




      All  Fsystwfitf1;  ussen  PVR  pri pe.     Bnhh  sn1v=*nt-. -wi-r l.rl  and cMFikt.'fci^d




l)  IV-ing pipe? hv  r^i.ir:r:ersf: u 1 1 y h*=ji=?n   u^^i'J.,     in  <=spp>i-:i .1)  oaKen,




di.ir:1".T 1 e  cuH^t.  iron  pi.pf=> h.ns  hwen   uf-.i-?d.

-------
                                VACUUM  S I AT
       Vacuum s;l".;"i t:*i nnr-i,  r:niTiei'.'i rni:ir-;  trfff>t'rt~'rt  t.o  /IFJ  no I l.or:t, i t iri

            r-:>   vary  f'rrnn  iiirimt t-ar:t.i.ir;ir  t.n  nmnuf ricLur ei'.    '! <-i I.  i (-  ;'-'

whriwf;  t,h(;>  varyi nj  i.1c*F,ri :^n  |:i;;ir .HiirLi-.if' :-;  lit  ^'.nc':! i  hype-1.

I  I pohiT] I i ix -m::l  linli.  vi4K'y  l.hf-vir  i.if-:?;  rrf'  v. KHJIMII  KI Tiwr'Vf   l..mi<;:

wi t.h <;'^cl'i  i nr:t,,H j I ai'.'i nn,   whi'h'  V;Hc:-Q- -T (-.  iinri  A FU'VAI i  u:;--

                    r^kK  bc-'t-.wp-.-f-.'ti  l.hr-'   r:n ) .1 r-'dvi ( in  V.cink  <-ind  l.hc-'  v.<:uum

       f;.   (Nut.e:   Tl'ic-.1  l.t-'rin  " (?*"?!' vr? L.nnk"   i ?;  ur:i-d  hy  .j I I  o1  l.ii--

ffifirtu t"rii : hi.iK f*rft   exr:i-.'i;i t.  A i  F?VAl I   wl-n.r:h t"rj }utjr :~~  t,< i  t.hi,:";  I., "-ink  ,i:-~.  .-1

"KTfr.i^rvci i K  tank".  )
ri-!r-u->r vn: r
                                     i ABI i
   i ' y f'i o

f-'.'l ect.m I ux



! -i i I t --En vj reiver:


Vac -IJ  T f-^i '


ATPVAf;
            _ T * i n k _

S^"F>i5iK'afc  hlai:k  ."iric'J  <^t-.sy  w,-it-.eK
v e s s e "! s .    R ft & e r v c>  h 
-------
                ifi.mu 1:t=i :t.i.trws  hav^ plnyed  vi  inn j in-   mli'  "in  i.h<~-

di.rivt~* i i ipuiMnt.  nf   VMr:uuffl  f>wwi:n'  MysjUi^inw.     1 hr-t-- <-  <-iKft   i Pin i"t "i <~,~

d'i r }(!' I-TIOC-T:  in  iivRfri|,j   raywl'.t-Jiii  phi i 'I r issr.ipHy,  ilfFii cm  r:nn-.r'|;iLi;

r-:y:'-"l-<->ni  i':imi|;i inwnt.S,   HfH'1  rn*:ir:h-'r;  i  Idtilc-'  HJ.

Wl ri  l.f;  "! I 1  1" rn.it"  w^ft*  '()  yt^Hi r;  i<.^n   in  i.l~i  lln.j t;.i -rl

Sti-i !.?:;.   i m I y  AIKVAi;  riar-;   r.:ont.i nuwd t.ri  pl;ur(-  r I-T--. i ilei il. i < I

syf-vl'.< 'in"  "inl.ri  rip<"'K'i!itt. .i on  on  ri  rt-'^u i .-IK  hi.i:'. i :-.      '._>( nti--  ol"  l.hr-

c--.(>-  ly :-;ysl'.Miii:;  of"  Cn!l t'.--|- ri v  i.r'rivai :  <-in i'J ar y
                                                      I'll
                                                      in
                                        No  rj*--f?i.pri  tn<-iiiii.:l

                                        In  hem r-itv
                                        Nn  iJp.'Ri cjn  fn.-tii
-------
a.    Basic: Oi/s
     Figure 5  shows the basic vacuum newer system  "layout,,

including the major nomporients.   This layout is ba^e'd on  an

AIRVAC type of system  ;-rinc:t-; it  is the innst common.
                             FIGIIRI-  !-)
                        MAJOR riflMPflNKNTS
                               OF A
                       VACUUM SFWFR SYSTKM

-------
     A  vacuum i-sewer  system oonrvi r.to of  throe (3) ma.ior




c:i irnponentf;:  the  vacuum station,  the noVI ^oti on  pip




the  r.ervi cos.   Each  i ;-~ dec-*< :i-"i hr-d  bo'lriMr.
                                SffRVTQES
                  1^1 OWK  by gK.'tvit'.y 1:K'om  one or" mofi1* hrnnftK  "int.o




     n 30 J35in on  holding t-.ink.   AK  t.ho sewage  I evftl  ri K*=J-; Sn




     i-,hr-?  Hump,  ."iir i.R  nompn-.'SSi-^d :i r> a  sensor- hubt? whi r:h  :is




     r:onnectr-d to t-.he  va'l.vr- nnnt.ro] l?r.   At. .1 pKfr-^t; point;,




     fchi"?  f>^nr;or rn.p)n.Ti]l.i3 'for the vaciaum v"i ).ve> Ko open.    I he*




     va!l v stayR  opien  1:or  an adjustable period  o1~ tim^ and




     then  closes-    Ourlnjg.  the  open  cycle,  the holding tank




     contents  ai-e evacuated.    The timing cycle  i r; field




     adjusted  between  ft and 30 seconds.   Thi?s ti inn- i s




     usually set  to hold the valve  open tor .-i tot -a 3  time




     equal, to  tw:i r:e the ti.me reQui.red  to admit  the sewage-




     In this manner,  atrnospheric fl'ir -is allowed l.o enter the




     system behind 'the sewage.   Thfc t..i me setting if;




     dependent on  the  val.ve 1 i:ir:ati on s i nee  the  vat:uunt




     avai.labl r will  vary throtj;^hou t thr-. sy:::l.i7im,  theKvhy




     cic:sverni ng the rate of  sewage tr 1 r>w.

-------
       Thw vallvF*  pit,  t.ypi::;vi I  I y  i.yj  1 ocHt/i-'d  o I nri'3 a  prnpechy

11 i rn.     '1 ho  Vt.il v<-'  pi t'./bn"l_d"i I'M;?  l-onk  arr cHnqi-Miiont-  (I" i <:?urr-

fi )  i.  ufujallly  nu-iiiU-; crt   1' ~\ tn'M'gl sra   a I t.hrH.igh  cm idl f'i r-rJ

":c mi :K p't.i-;  inanl'ii > 1 (  r.ivct.1 nnr.  l't.-ivr?  bi-v<-';n   UK<-'<:'  I-CIK  :-;p< >rri a I

rri t.i.i,--i h~i nnf.  ( rloop  ham-inonhK,    t iriK-^i".-  U;-:?K,   (.n r';;:;ii>  (/v.ii :utnn

i rrl.rtKf-ai .i'., (~'t.i:)-    A nnn hrat )'"i r:   I i.ght.wi-: i  i^hl,  a'l I.IKH mini  nr

car:t;  i.rcin  .lid  .1 r-  aval l.ahT 
-------
GDI I Jrl'-.l DJN PIPJNG
        I ! ft  var:tjijii  i :ol 1 r-n : I, i nn  p'i p i n;J)  iif-uju-il !y  i :< m f-;;i r:t.::  ni




 (> :i nnh,   arid  4~"iiir:h  main;:,   M I l.hi HIM! i  rnrif <"  KIM u-ril.





 "insl-dl I..-.1 h i nn  H I MI i  i nc: I ndr-*  8-lnr.h mari n:-s  in  Knun*  < :.:i;:c-;




 h>ma I  I (-.'K   (3  irioli)  irr.i i n:-;  (.r;(-r:l  in   i';ar I y  vac:uuin  r-.y.-;l.i MII..  ,




 rut  iiiii<:3tM'  >"(->c:riinn)f-*ni"lf-'i J,   -u:;  V-hi-1  ci'isii  ?;riv i nu;-;  1 11"  ii  iut:ii




 4  inch  .-iff conn i dt-.'t-vrl  Ln  t:ur>  i n i cini -f: i c.m I-,.




       Rribh  .'>i 1 1 vwnt.  weldi-i-l  C'VC  flip*--  .irtrJ  i'(jhhrjK-  ;?..iMl  St-M :t. i t in  !),>')-    Wl n''rt'' ruhber   gHtskHt-.*--!  inri?  u5-.t--ri,  l.|




 mur.t. hfi  cirfftii 1-ied  hy  i.ht-  inanu t'-u :l.ur'<->r  .i<;  t'iei.n;:j  raji i.vi




 frn-  vrinuijm  swrvi. CP.    I hr>  man n  ::ife  oieru^ral I y  'La if I  i-t i




 t,he  sanift  c-;'t ope  as  i.hf^  g^Mund  wi t'.l'i ;=i  irri.ni mum  slop^'-  i'if.




 . '.'''.    ) OK  UphJ 1 1   t.KiHriKpOKl".,   "I 3 1:tvF! i-'lKPf  T' I .4-;<-fd  i'.ii




 in'i ITJ rnri ^e  *-;xi':.:ivrit, i.nri  cJnphh  ( Fi CIUKW 7).    Ther"*.'  .-IKI^  nn




 itirtr^ in I.HI-S  in t'.h^  fsy?;t'.i-'fii,   t'towr-'Vtvj-' .,   fii':of-rir>  r:.:s.    D-i.v-i.a:i < m  valvi-'  in.-iirir.  t.n   .-:i') l.<">w  f-'or"   i f><">1 t^tinn




 wl-ii-'.-n  trcmh I erjhiool'.'i n-.j  rK   whuvn making  K'ppad rs-v     P i  uj




va i vrt  and  Kt'.'sxl'i.tvfnV.  wi--jdnf  qahe  valves  h.Hvc;
                                                            IKI-
                                                             I ^
              1!".

-------
                UPGRADE TRANSPORT
///=/// ///=///  //'=///=
                                                 FLOW
              LEVEL GRADE TRANSPORT
LAY SEWER TO A FALL
Of NOT LESS THAN
0.2V DO NOT ALLOW
POCKETS TO FORM.
               DOWNGRADETRANSPORT
                                                 FLOW
                  FTliURF 7
      UPW-MOE/OUWNiilMDH/I.FVFL TRANSPORT

-------
                          M  51 AT TON
     The  vacuum station  !;:>  the heart of 1..h-  vacuum s^'wer




 system*   Tt Is similar  to  a conventic ma!).  st-?w-ge pumping




 station.   These stations are typically two  (2) r.tciry




 ooncre te  and hi nek  buildings apprnxi.inat.pl y  ?'.V  x 3O"  in




 1:!LrH"iK plan.   I- qun.prnenh  in  hhF* ?:V.aV.:i r m iru:::'l mli^r-i .-t




 collection  tank,  a  vacuum  res*-rvolr  tank, v.-icutim puirip^,




 sewage pumps,  and pump  cfinfcro'J.s.  ( F"i ijuK-e  ft).   In




 addition, an emergency  generator  is  standard  equipment.




 whether it  be Located within tJ"iFs  stat.jnn, outside the




 station i.n  an eric Losure, OK  of the  portable,  t.rur:k




 mounted variety.




     The cri'l I. ect :i nn  tank, made o'f  either steel  or




 fiberglass?,  i K the  equivalent to  a  wet well in a




 conventional pumping station.   The  vacuum reservoi r




 tank is connected directly  to the col 'lection  tank and




 nerves as a  buffer  to reduce the  frequency  oP vacuum




 pump starts  and thereby extend their  !l.if:f-  The vacuum




 pumps can be either "I i quid  ri ng or  sliding  vam-- type




 pumps.   These pumps are usually si^ed  -fnr 5 to 8 hour;;




 per  dav run  time.    I he sewage discharge purnps are nan




clog pumps with sufficient  net positive suction head t.n




overcome tank vacuum-   Level  control  probes are




.installed in the  cnl'i eotinn  tank  to regulate  the sew.tg^




pumps.   Vacuum switches on  th*-1 reservoir  t.-ink regulat*--




the  vacuum pumps.    A fault  rnon.i horn.ng  system  alerts  the




syt-~tem operator should n J ow vacuum or hi gh r>wage




level  condition occur.




                           17

-------
              VACUUM
               PUMP
              EXHAUST

POWER
VENTILATOR
FOR TOP
FLOOR
                                                                       VACUUM  RESERVOIR/

                                                                       TANK
                          CONTROL
                           PANEL
                                                                          VACUUM GAUGE
                                                                          ISOLATION VALVE
                         VACUUM PUMPS (2)

                              '	^\
                              EQUAUNGJUNES (2)


                                     NJR
            FORCE MAM
           TO TREATMENT
               PLANT
                           COLLECTION
                       DISCHARGE PUMPS (2)
L_
                                             T ITillRF  K
                                          DIAGRAM OF A
                                     TYPl'llAI  VACUUM STA I'TflN
                                                  i r:

-------
     Vacuum OK negative  pressure sewer  systems use vacuum

pumps;  ;-it  central collection stations t.o  evacuate air from

the  lines,  thus creating  a  pressure differentia'!.   In

negative  pressure systems,  a pncH.iniat.:i ca.l I y  operated valve

serves as the interface hetw*^en hhi^ gravity syr.i.wm from thr?

ind:t.v:.i dual  user and thus vacuum pi pelri nem.   Pre;r.ure enKorr.

in a wastewater hoil.dina tank opwn and  clnse the interface-

valve?  to  control the flow of wastewater  and air into the

vacuum system.

    The normal SP*CIUen"::-> of  operation is  as  fol-.lciws:
        Wsis3tewatpr from the  individual, service flows by
        gravity to a holding tank.
        As  thei level in the  holding tank continue;-' to rise.
        air is compressed  in a small diameter sensor tube.
        This air pressure  is transrni tted through a tube to  the
        controller/sensor  unit mounted on  top of the valve.
        The air pressure operates the unit and its integral  H-
        way valve which applies vacuum from the sewer rnai n  to
        the valve operator.   This opens the interface va!J ve
        and activates a field adjustable timer in the
        controller/sensor,.   After a set time period has
        expired,  the interface vaJ ve e"loses.

-------
     *   The wastewater within the vacuum sewer apprnxi mates
         the form of a spiral  rotating  hollow cylinder
         traveling at. 15  to  1.8 ft/sec..   Fventually.,  the
         cylinder disintegrates from  p:i.pp fri ntri.nri.  and the
         .liquid  flows to  low p<:ri nts (bottom nt lifts)  In the
         pipe"! ine.
     *   The next liquid i.:yl..i rider and the  air behind  it will
         narr-y  the liquid "fVorn the pK^viouw disintegrated
         r:yl i riders up river  the Raw tonth li.ft designed i.nto
         the system.   In th.J FS  manner, tl'ie  wastewater  IK
         transported river a  series n1~ 3j.1"t:-: tn tl-e vanuuin
         station.
     The princip'l.es nf operation of a vacuum ewer system have

not  been completely understood.   An earl y  concept wacs  that o1:

liquid plus flow.   In this concept,  it was assumed that a

wastewater plug  completely sealed the pl.pe bore during static

conditions.   The movement o1:  the plug through the pipe hnre

was  attributed to the pressure  differential behind and in

front  of the plug.   Pipe friction would  cause the plug to

disintegrate,  thus breaking the vacuum.   With this being the

situation,  reformer pockets were located in the vacuum sewer

to allow the plug to reform and thus restore the pressure

differential (Figure 9).  In this concept,  the re-establishment

of the the pressure differential for each  disintegrated plug

was  a  major desi.gn consideration.

-------
               MAIM
                         FIGURE a
                  EARI Y DF.SIRN CONCEPT
                     REFORMER POCKETS
   ! th.  nurnt *!. cnnPt. the

           ~ th-t th-  *-r *-. not ,
    p
                                                 pock.*,
                                                ,he
           Th.

th, pr^tnu-lv
     -  th.
                          cond.tinn

      peline (Figur. 1O).  Tn H. nc*.

            .1. the f*. rf . -Pil-  -"

                           th.  t t- -n- t>-

                          - cyl.n* ovi- .

                           tum  of

         it, contrdbutix-  tn  th.

liauid pont              n. .lu-   -

consji.disrati.on.
                                                           n,

-------
AIRSPACE
                          SEWAGE AT REST
                             '  FIGURE 10
                         CURRENT  DESIGN CONCF'PT
                          PTPF BORE NOT SFAl ED
         Bnfch of  the above design  concepts are  approximations and

    , .verw itnplifications  of a r:rimpj ex, t.wo-phase  flow system.   The

    , tu-irai:ter of the fXow wi thi.n  the vacuum sewer varies

    , > msi derably.   The plug flow  concept,  Is probably a  rftaf-srmab t e

                    of hhe flow ^s  i.t.".ent.->rK the syetom,  whi-rt (->aw l.h

                  mcivwtnent nnricept.  IK probably a betLeK

    .i.(.mxi.mafci.on  of t.he flow throughout.  hh vacuum mai.n,

        1 hf^ significance of the axr as a  riri.ving forcw  cannot  b<^

    ,.v'!rt-'fnphaKi ^ed.   The atninKphf-iric: air  expands w~i th'i n thif ViH.i.n.i

    ..wr*r,   thtJi?  dr."i.vi.n<3  the I 'i qui d  forward.   The air affectF! not

    , ily the liqui.d in the atsKociated air/liquid slu3,  but al?;o

    > -! 1'iqui.d downntream.

-------
*""'-
    iable 4 shows {genera"!  conditions t.hat are conducive t.o  t.hi

selection of  vacuum sewers.
                                  TARI. E 4
                         CIINDT ! TUNS  nUNDllC ( VF TTl
                         VACUUM SEWH-? f-iFIFOTll'IN
                      Lin stab! t? r-icn Is
                      Flat V. Rr ra i n
construct-lon
                      High wahi^r  tab 'I =
                      Rock Unusual  or
                      Deep t:>'iKfiinenl,fr:
                      Low  popu] at.i on density
          peirienaw has whown hhat  for vanuum nywt.c'ins t.o be  norat.-

   1:fectlve. a  minimum  of 75 t.o  100 nushomers s  needed

   vanuurn station.   The  average number of  nustomer'Q per- s

   in systems presently  in operation is=i  about 200  to 3OO.

   are a  few systems with fewer than 5O  and some with as many OH

   200O customers p
-------
*!.  If ?< tent  Q U-f-s? i.o.  tbs               .

    Table 5 shows the operati ng res;:J dranti a']  vacuum  sower  s=syntiams

in  the United  States,  a55 of Decr-Miiner  1 HftS-L   Tl it-*re  .-ire  anothoi-

dozen or so present, I y i n the r:onstrur:ti on phase, with  rnrrre he-ing

planned and designed.

                                  TAHI F 5
                                  LJM._SYSJT:MS	JN_.THFtJ.LS-_
                     T
                     TIA
                     TIB
 PROJFC1	
 Marti nghatri
 Foxcil :i r f e  Fstatns
 Country Squire  Lakes
 Mathews Courthouse
 PI ainvi Ile
 Fastpoint
 Wfs tinoc'i--1 Lan d
 Fal.il en  Leaf  Lake
 1 Ipper Fairmont
 Uueen Anne' s County
 L a F a r g e v i 11 e
 Char 1otte
 Ohio  County-Phase
 Ohi o  County-Phase
 Ohio  Coun tyPhase
 Friendly PSD
 Central Boaz PSD
 Red Jacket PSD
 Washington Lands PSD
 Cedar Cove
 Lake Chautauqua
 Laa Marina
 Einmonak
 Swan Poi.nt
 Alton
 Whi te House
 Morristown
Lake Manitou
 Therewa
 Sanford
 !-u"iuth Seas P.I an hati 01
 No or vi k
 8i g Bear  I  ake
 Cert ter town
 Stafford  Township
 Ocean Pines
 I ake of- the  Woods
 Sh i pyac d  I'1.'] antations
 Pfi I met to
 Captai n' n
. P.KOJEQIJJJLJAT TriN_	_	5
 St.  Michar-1. Md,
 Ma r t i n ; v i "I. I e,  T n d-
 NoK'th  Vernon, ilind.
 MathrjwK,   Va.
 Pil .'ii nv i. 11 e,   Fnd..
 Far-stpoi n t1.,  FT a.
 Wnr-ttniore'l.arid, Term.
 South  t ake  Tahoe,  CA
 Somerset  Co, , ML)
 tJiiRt^n  Anru"'* K  County. Ml
 I al- arjgevi I 1 e, N. Y.
 Charlotte,  Tenn.
 Wheei) i.ng,  WVa
 Wheeling.  WVa
 Wheeling.  WVa
 Friendly,  WVa
 ParkerKburg.  WVa
 Red  Jacket,  WVa
 Washington  Lands,  WVa
 Lexington Park,  Md.
 Cel errin,   N. Y.
 Norfolk,   V,i.
 Frnmon.'ik,   Al=iF5ka
 Swan Point.  Md-
 A'lton,  Ky
 White  Hou?-:.-,  "tc-nn..
 Mnrri fjt'.owji,  N. Y.
 l?oc:h*?r;ter,  I nd-
 ThereNa,   N.. Y.
 Sanf ord,   F 1 a
 Fort Mt^yeKft,  F.l.i.
 Nnorvi k,   A i .'irtka
.R.i <3  Ruar  i. ake, IIA
 C-?n ter town,  K Y
 Manal'iawki  n,  N. ,J .
 Reri] i n,  Md.
 I oc:ur;t l-irrtve. Va.
 H t I tun Hi-.-, i-1   11: i an j., l-:C
 Hi I trin Hi-, id   i:. ! i-mci, !
 t'.!i' e^-nh-tc:!-,,  Va
:;YSTFM
    AIRVAC
    ATIVVAC
    ATRVAC
    ATRVAC
    AIR VAC:
    ATRVAC
    A mVAC
    A IRVAC
    ATRVAC
)    A IRVAC
    ATRVAC
    AIRVAC
    A.IRVAC
    AIRVAC
    AIRVAf:
    AIRVAC
    AIRVAC
    ATRVAC
    A IF? VAC
    ATRVAC
    AIRVAC
    ATRVAC
    AIKVAC:
    A I RVAJ":
    AIRVAC
    ATRVAt:
    AIRVAC
    AIRVAC.
    AIRVAC
    AIRVAC
    I-NVTRIIVAC
    FNVIROVAi:
    FNVIROVAC
    FNVIRnVAi:
    hMVIROVAC
    VAC-Q U -C
    VAC P TFC
    VAC--O--1FC
    VAC-U-fFC
    VAC u-Tl-i:

-------
     In  addition  to  the* ahnv*-?  K'esidRnti a 1  wypjl'.i^fiu-s,  si'Vtrtral




industrial  f'ar:.i t i t:i !-.:> use  var:uum  ray stem;;  to  noil I p-nt wastf=*wat-'r..




Tl-ic?se  :ntnparri *=s  .include* t-hi-1  ScoLti l'.--ipn>r  I Irnnpany  ptil..p  and p.-ipx-i-




mi  t I  .-in  MobiU>,  Alaharnn w:i t.h 2b AIRVA1"!  va Iver;.  SLiern meirHjf;ac1l-.ur<^r,   J<-^r'ad




Industd *=,   zi.n  many  c:hiptinard incfca11ah.-i.ons.    Thwsf  types of




instal 1 ata.nnp;  are beyond the-; scope nf: t.hi.s frrpriKt.,   and WT 1_1  nrii-.




b r*  a d d r w s s e d,

-------
    Many myths exist concerning vacuum sewer : iytjiu-mr...   In many




ways a vacuum system is not  unlike  a convent'! on a I  .|i'avitry




system.    Wastewater flows from the  individu.il homer, and iitili ;-;




cjKvivi tv to  reach  the point of  connection  to the public  r-;nwer




The 1 i.ne  materials are  the s
-------
MY TH:
Vacuum  Kewerr-i  should not  hi-- c:on i d-?r<-d when




natural  gravity exists,.
Rt-AI J'TY:    Many timer-;  a broad view at' an  <-i>(-.-r :-.  1.i->rrrri n




              automatically  rules out. vaoiium ^fweri-s ar:  an




              alternative to he  eon wider i-*d..   However,  .-1 i: linger




              look may reveal  many snu-i I I  arJvanl,aQi'--r-;,  bi"ial.,  wl ion




              r:i insri dered  r:o I t.ei:tivp.'.l y,   add up to *  :
              :>.-iv:i ngs.




                     A  f n ne exanif;) l,e inf l;hn t:  nnruirrr.-d  i n  t.he  llhio




              Kfuinhy PSO-Phasi' ITA project,,  in  Wh<-M> I .inq,  WV..    In




                        jech,   .it. only  siawmrj  loqxr.aA  t.ci t,hfj




                         to  UFS  jjravity rjewwrf-;..    Vh>? ai^fta was




              rural with resi.d^ntia 1  development fci.l.J nwi .ni  a




              creek.  '  However,  upon  nloser  rnspir-rifc. j on,  it waw




              evident  that the gravity main  would tie  requi rod  tri




              cross the creek  in .various  p"U   With t.he*  <:rtT*n-k




              bank  being 3.0  feet  deep and the <-; eek i-.Konj>i n;-i




              requiring 3  1~oot of  c-.over.  the i^ravi I'.y  Mt>wt-t-  would




              have  been 'V3 t'eet deep for  mo;'-.t u'l  ri *.:?   I i--n!'4t^i




              (Figure  11)..

-------
                 V    V
          /    /  "7   /
  12
7
7~7~1

                    BEDPOCk
                        11
    liRAVJTY SI-WFR SYS IFM FXAMPI.
was  KoJ id rm::k,  tJ'ie  en hire 1 ^n^W'i :rl  b

   f:avt3 on wriuld hav*-? tii->n in  ru:;k.   At, i.
      rius  nt  |-.h syKt.em,  a    'M.  wt.rl'..ori wa:-;  n-^rirf

t.o  pump t.l'it? r:ftwage  fr.i'i a pliini",  wlvi v.l't  wa  lnr:-rhf-?rl

abrive t.h "I.OO yf f:'l rind elevahinn ( K'-j.iqi.ir**  11).

-------
By  utilizrri n<3 vacuum,  the  detiri gner used  "lifts" to

raise the  main above the  bedrock  ] evel  to  a depth

of1  4 OK 5  feet (Figure 12).   The  vacuum  station

V.l'iat wafi required  was ncithi n3 rnore than  the "lift

statinn that was required in the  3',=iivi t.y layout,

with the exception  of the flddri t-i cm n1: vacuum

pumps.   This additiona I  expense w.-is KinrF- th-an

offset by  the savings of  the  line lnKt<=)11..it;i.on.

The "inexpensive"  gravi t.y system  would  hrtve

Kequi.Ked c:Jeep,  da.ff i cult  exr.:avat:i.nrif. with  much

nr:k.   The  varrutjrn  a'l ternati v*-.- had much  shallower

rjxcavations with little r r.i(:;k.   In e:>r-:enc.e,  the

vacuum system war:  installed .=1?: a  "vacuum assi.sted-

gravity sewer" with significant cost savings.
                                    BHDOOCK
                FIGURE  ].?
            VAHUUM-ASSISTED
          GRAVITY SEWER SYSTEM
                 EXAMPLE
                   29

-------
      MY I H:   Sinr:e vacuum  {--sewers are  in<-
-------
 MYTH:
                1 he  vacuum  pumps must run  x'4 hour:--.  .~i  day to  ki-'<>p



                var:uum c:m  the F?yKtr*m_
 RFAI  TTY:    The?  typlo.Hl  vacuum  Kt..it,ion  i ;;  dp;s:j cin<1  Ro'"t.h,-i |-  Khr-




                vacuum pump;1,  < ipftrc-ihi   atn^ut,  Fi hourr:  =i  day..
MYTH:
                                          " iur; .-unounh nl1 F?rir?r;:jy t,"i  k =- p
                                       on
IVIrA!.. I I Y :     Thft  averagw  -;i;'(-;d  vAi:uum  :;t,at,ion  r:rint.,-i-i n  >*O  hp



                vacuum  pumps.    r.nnrrj citur-'i ng vin  riv^roi;:^  fun  h'i me  " if




                S  hours a  day  and  the r-nst nf  e-'l.Rct.r ir.:i hy  -it.



                $. 08/kwhr,  t,hr- monthly  nost  rcf powr fnr tihw



                vacuum  purnpFi :i K  about SI 85.    A system  thri r-: KI xe



                ortn  and t.ypi cfll l.y  do.n-s  r.ervir^ ?0()  to HOO  cur-; hrmu^rr.
MYTH:         The operation  of"  a  Viii-.uuiii  r;y:--.ti




                wi th  =t  r-.n.l Lf.fift rJw.^r f-'t.1..
                                                                            a per won
RFAI TTY:     Any person 1.1'nt  -j ?>  mt-M:hanxr:a.lly i.nr:l n.nt'-
-------
MYTH:          I t;  -the  vacuum valve f:a i 1 f.,   Ke




                 into  rny hou ;-;<_
                                                                      j J 'i   har-k  up
 RFAI.. 1  ! Y r.     Vacuum  va i ver.  can  'tVri I   in  ei ther  tb   < i|:ien**-< it




                 i : l.owi >rj  poc-:i tvi on.    line  fall i n<3  "t n  l.!pn-j  r:1 owed




                 piOK'j V."i cm w~i II  fHsu'l t.  i.n  Ltcir.kiips.    I l~n rs  wiuli'd lrn-r<




                 ana.l i IIJJOIJF.  tri .-i  hi nrikfis-TiM  nr r-iur cht^f <:n ri;:;i  rif  a




                 cjr-.-ivi.t;y spweK.    Fnt-i.tjnt-i-'"J y,   1 .-< i lure  in  t.hi FS iimrJ




                 is (-jxb.r ftiMt=f I y r.-u'if.'.    A I rwir.1'. <:i I  I  v^=i I vr--  1r.Tt 1 uK'tj:>




                 hctppfn  "in  thr-  i ip^n pns3.t.inn.    This?  u".-.-in^ t^hal.  t.V'i




                 var:i.uiiii  rrnnt/i niiRin t.o  work  1".r>  ev<-ir:u  up  rir--.   this  f.-ri.Ture  P: i mu Lnhes a  line hfenk.




                 I'n this  cas t,hpf t;- I. t=?phrm dialif-r nnt.i f:i ":; hhe




                 rtpRrfttor' c1:  hhi.s onndi.t.i on,   whi.ch ,i f.  Q&




                 r:orrot.ed  in "I ei-i  i.han  iriri  hour.
MYTH:
                Th  vacuum rrifi i n  has  t.n be  deep ennucjh  tin drain  1.1 I
REALITY:      Tn  a  aravi.t.y  fn-jwpr  i.iynut.,  ono  i"Jeo  !:.i."11 ;-; nu- n r.  m.iv




                 tli.ct.cite  thw rit'*pLh 
-------
u
                     - 
-------
I I.   VACUUM SEVER SYSTEMS




     A.   INTRODUCTION

-------
                       SECTION
        The  use ami acceptance a1:  a I ternative wastewater


 col I eotion ?:yr-;temr-: has; expanded  greatly in  the  last,  2?)


 years.   Urie of these  alternatives,  vacuum sewers,  bar; been


 used  'in Eurnpe for over a  100 yearn.   However,  'it ha hwr-ri


 only  in fchw I a?-;t  /-"S yoacr-i  or FSO  t-hat,  vai::i-iufn tKanspnrt. hart


 be? tan  ut.i i i j'ftd in  hhw  ilnit.Rd St.aii.t=JS5.    Tn t,h"i. F: r--.l-iort; pir i rrj


 nf- time,  si grri f:i cant.  :i rnpirovement.s have hf-;p?n madt--  in  systu.-m


 cnmpnnRnhK.    In  addlVi.on,  *-xpK"i i-?nc::ft wi t,h  npi-?rftt,n ng


 Kystamsi ha?: led t.ci advannc-ementifj  in  rlwFii.jgn,  r:nnf~t.ruct.i rin,


 and op'^rat-i rina.'J. t.^nhni c^iies,   Thf?sw  f:ar:V-OK'r:  havft all


 onnt.fihuted t.n var:uurn  sewer syst;efns tiei.n<3 a re.liahle,  nnst.-


 ef-feoti ve  a't tf?nati ve  for wasit.ewat.Kr cnnveyance.


       Vacuum  sewerage  H a  mechanised syjr.t;em nf wast.ewat.er


 transport..    Unlike gravity  flow,   it, ur?es di.ft erent,i ri I  air


 pressure to move  the fsewage.   It.  requires a central  sourne


 of power to run vacuum pump?; whi.rrh  maintain vacuum on the


 cci3 lection  nyctem  (Fisjure 1).   The  system risquirer. a


 normaH 3.y closed vacuum/gravn ty int.erface valvr.-  at each


 entry point to seal  the linen F.O  that vacuum is

                                       *
 maintained..   These valves,   located  i.n   pit.,  open when a


 pre^etermi.,ned  amount of sewage accumu tates  in the


 collecting  mirnp.    The  resulting di f ferenti.al prr-Fssure


between  atmosphere  and  vacuum becomeK  the driving force


 that propelr:  the sewage towards* the vacuum  station.

-------
               RIVER
FORCE MAIN
                             t
                               L
TREATMENT PLANT




c
c






c
Q




1
c


VA
ST

*ji
JK

M-
4

1

UNE B-J






C
a



:
a














C
c





d
13


C
a



1
D














C
L7

*  LINE A







            PLAN
             FT.lillRF  1
          TYPTt.AI. I AYl'ltir
      VACUUM S'FWFR  SYSTFM

-------
       A vacuum system is very similar to  a  water system,

 only the flow is  in  reverse (Figure ^).   This relationship

 Mould be complete if the vacuum valve was manually opened,

 like a water faucet  is manual ly opened.   Wi th  proper
                                                        *r
 design,  construction,  arid operation a vacuum system r:.m he

 made to equal a water system in terms of  rwli. ahi I i ty.
                                      "OHt
                                          moat
                                          PUMP
                      WUE
                                     OOUEEIION
                       WIVE
                            FI6LIRF 2
            WAThR SYSTFM/VACUUM SYSTEM STMII ART I TFs

       The choice of- collection system type is usually ma

by the consulting engineer in the planning stages.   Thi.s

choice is the result :1: a  costef'feoti veness analysis.

Where  the terrain is applicable to a gravity system,  the

vacuum system many times is  not even considered.   Wh i !Uj

gravity may be the casteffective in these situations,  many

small  factors considered collectively may resuil t  in  ."i

vacuum system being the proper choice.   Vacuum  sewers

should considered where one  or more at the Pol. lowing

conditions exist:
*
*
*
*
*
*
*
*
             Unstable w
             Flat terrain
             Rolling land with  many small elevation  changes
             H:i gh water table
             Rock
             Deep basements
             Unusual or rer.tri cted construction  ormoi 1 1 ons
             Low  population derisi.ty
                               3

-------
     Th advantages of  such  systems may include substantial

reductions in water use, materials,  excavation casts,  and

treatment expenses.  In short,  there is a potential for

overall costeffectiveness.   Specificail ly,  the following

advantages are evident: 

    *   Small pipe sizes,  usually  3", 4", 6"  and 8" are used.

    *   No manholes are necessary

    *   Field changes can  easi.ly be made ;HS unforeseen
        underground obstacles can  he avoided by going over,
        under,  or around them.

    *   Installation at shallow depths  eliminates the need
        for wide, deep trenches reducing excavation costs
        and environmental  impact.

    *   High scouring velocities are attained,  reducing the
        ri sk of blockages.

    *   Unique design features  of  system eliminates
        exposing maintenance  personnel  to the risk of H S
                                                        2
        gases.

    *   Very nature of the system  will  not  allow major
        leaks to go unnoticed resulting  in  a very
        environmentally sound situation.

    *   The interface valve isolates each home from thi^
        man n,  making it impossible for  system flow to
        backup into a house.

    *   Only one source of power,  at the vacuum station,  is
        required.

    *   The elimination of infiltration  results in a
        reduction of sl^-e and cost of the treatment plant,

    *   The air/sewage mixture  enters the sewers at high
        velocity with the air providing  a high degree of
        mixing action of the sewage  inside  the vacuum
        sewers.

    *   The short detention times  in the receiving vessels,
        along with the introduction  of air,  do not allow
        for sewage to become septic  thereby resulting :i n
        the lack of odors.

-------
    In Chapter I.C.1, the history of  vacuum  sewer




technology is discussed.  The differences  in overall  system




philosophy, design concepts, system components,  and




marketing approaches of four manufacturers are discussed.




Each of these companies have made significant contributions




to the vacuum sewer industry.  Presently,  most systems in




operation in the United States are AIRVAC  systems.  For




this reason,  the remainder of Chapter III  will focus  on the




AIRVAC approach.

-------
I.   VACUUM SEWER SYSTEMS




    6.   SYSTEM PLAN AND ELEVATION  VIEWS

-------
                          SECTIONS


.S_Y_S_!_E_M	E_L_A_N	A_N_D	E_L_E_y_A_I_I_Q_N	V_I_E_W__
                          FOB A 8* SERVICE LI*C OK 4' VACUUM MAINOKLT
                   DC9WH MOFIUS FO * ON LANOEH VACUUM MAM ONLY
                            OF
                       PLAN  AND PHOFUF: VTEW
                        TYPTCAL VACUUM I. TNE

-------
!   ll
                         17
           PI...AN AND PROFTt.F  VTFW
             TYPI.I:AI, VALVE PIT
                         2

-------
ill.   VACUUM SEWER SYSTEMS




      C.   DESCRIPTION OF  ALL  SYSTEM COMPONENTS

-------
                    SECTION    C

                    Q_E	S_Y_S_I__M	Q_Q_M_E_Q_N_E_N_I_S.
 1.
       The services In a vacuum system  confvi.st tif; the

f ol I owing components :

       *     Vacuum valves
       *     Valve pit/sump
       *     Buffer tanks
       *     Auxiliary vent


       The vacuum valve provides the  interface between the

vacuum in the* onllection piping and  the  atrnospheri c air in

the  building sewer.   System vacuum :i n  the  collect-ion piping

is maintained when the valve is closed.  With the valve

opened,  system vacuum evacuates the  contents of the sump.

The  valve is entirely pnuematic by design,  and has a 3-inch

opening size.   Some states have made this  a rninumum size

requirement,  as this matches the throat  diameter nf the

standard toilet.

       Valve  pits with sumps are needed to  riccopt the wastes

from the house.   These consists of two ('^)  separate?

chambers.   The upper chamber houses  the  vacuum va'l VR..   The

bottom  chamber is the sewage sump into which the building

sewer  is connected.   These two chambers  are sealed from

each other.   The combination valve pi t/sump :i s made nf

fiberglass,  and is able to wi thstand traf f :i c 1 nads.   These

-------
are  avaiJab'I.e  :i n  two  (2) d'j t'1"ereni. dephh  :- i xi :---.    should  a




deepen settri ng be  needed,   the friberglaf^;  pi t./r;ump




arrangement  may he  replaced  by  a  r:orir:ri?t.e tnanVni I * ^i-.-otvi tin




in wl'iinh  i,\rw vnouuin valvft  ir. rnot.int,ed..    In t!"ri r. .:ir-ransir-jfnftni"..




fin.} y nrie  r:h^mbF?K"  exir.t.K.                                        ****




                      kK  are  u?;ed  f;r>r  l.=(r;:ie  < uit-il.i'mn-'r?-  nr  wl-ien  ,=




                      or  rjravi hy/v.;ic:uuni 'i rit.eK"t".:-u-:e H  i:li-js-i red,  ft ft




wmrld  be  l,h(-- cafte  with  n hybrid  i.i-inkf;




con^tril. nf- rnantinle  s-*r:tn nns  that  =ire c:ur-:l.oin built,  to




i.rinl ude f-.timpri.  rnu I  t.i.p] e  valves,  and  otlioc m \ -;i:< -1 I a

-------
vr>
 i ii*it=?
                                                                                 ru?-"iK
                                                                       m
         A  A  i nr:h auxi  I i .:iKy  vent,  \ K  ~\ ru t.t-i "I .I t~f.l tin  hhe

hncHF?owner' K  servi <".?'  1 citer;5! ! ,   rtnwnFstre.-Hm rrl  a I 1  i it  th*71  riiuJ5>*';;

hf'otpf;  ( F"i ;;)UK'i-!  pi).    Th'i K Vf-.'i'i'h  i K n<';jr:fv.'nKc:iK'y  hn pr ft vide  t,l'i^;

          nf:  ai K'  t.hatv  WT VI  t"nl I nw  hl'io  :=:(- wet  vi-",'ri1".  lvo  hi-* I

                                            .hfitii r: and prnt,^r:hT

i--f--.--)p,cins..    Jn  c I 'iiruHt-.ws   whore  t.eiiipf-'Kal.ureK 1:11  helriw

("('m^x'i n<;i,   1",l ri . s vent  rnuf?l",  he  lonal'.i^d .-1  mini mum  nf'  ?()

from tJ'ii-- va I v^' pi h.    In t-hi.s  manner,  Uhe heat  I'rorn t.he

Bt-WHt^iv cinh:-:  t.ci warm  the f:ree?ri.ng  <:itrnt:if.phori r: a:rr  t.hurt

reducing V,hie  pnssi h:i . ~l.i t,y  nf:  freezing of; srimt-! o1: the valve

nnmpnrien hs,
                                    - < VENT  NEXT TO HOME
                            VACUUM MAIN
                                      FIRIIRF Fi
                            Al IX TI. IARY VFNT  I III.:AT 1 ON

-------
       The collection piping network r:onsi nts of the

f oj I owi 119 components:
       *      Pipe
       *      Fi tting
       *      I i f tr;
       *      I >ivi.si an valves
       Th piping network is connecterJ to the individual

valve  pits and the collection tank,.   Schedule 40. SDR 21 or

SDR  2F; PVH pipe is; used, with SDR  26 being the most

common.   Roth solvent-welded and gasketRd joints are

acceptflib I e.   Experience has shown  there to be 1 ens protil ems

with the  ga^keted type? pipe.   Where  gasketed p.ip-e is used.

the  gaskets rnufjt he certi f i ed for  use under vacuum

conditions.   In special cases, DS'ITP  gasketed pipe may he

used,  providing the pipe is vacuum tested.   Typical sizes

include 3inch,  4-inr:h,  8-inch and Oinch.

       PVC pressure fitti.ngs are needed for directional

changes as well, as for the crossover connections from the

service line to the main line.  These fittrings may he

solvent-welded or gasketed.   Again,  the recent trend is to

avoid  solvent-welded fittings where  possible.

       Lifts,  or vertical profile changes,  re used for

uphill liquid transport.  These Lifts are generally mad*- in

a sawtooth fashion.   A single lift consists of two (2) 45-

degree fitti.ngs connected with a short 1 ength of

(F i gure R).

                               4

-------
                            45 PVC SOLVENT WELD,
                            SCHEDULE 40-DWV
                            FITTINGS
                                SCHEDULE 40 OR
                                SDR2! PVC PIPE.
                         FIGURE 6
                       LIFT DETAIL
       Since vacuum sewers are exposed to repeated  energy

 input,:;,  pipe movement is possible if proper i nstallati on

 practices  are not followed.   Early systems used concrete

 thrust blocks at each fitting.   More recent systems hove

 been  installed without concrete thrust blocking.   The

 theory behind this is that the pressure is inward  rathr

 than  outward as would be the case in a positive pressure

 situation.   However,  a more important concern is that  each

 fitting is  a point of possible joint failure.   Failure of

 the fitting may occur because of trench settlement rather

 than  "thrust".   For this reason,  care must he exercised in

 the backfill  and compaction operations.   Granular  backfill

material covering the fitting coupled with mechanical

compaction  is a must if thrust blocki ng is to be

eliminated.   If thrust blocking is used,  a thin plastic

membrane should cover the pipe prior to the concrete pour.

                               H

-------
       Division valves ar^- used for  iso I ,nt ion  purpose:-;




during troubleshooting.   Both plug  and rersi lient wt-*dge gate




valves have  been used.   Recent ssystr-fms have included  gauge




taps i.nstalll.ed Just  downstrecim i">'f" t:t'n-:j di.vision va.l ve.   Thin




gauc|p> tap makf?-s it possi.b'l.t-""  1:cr nnr in<"in to  trnubl ershoot




without having to check vacuum at the Ktation.   This




greatly reduces emergency maintenance expenr-ses,  Lioth  f;rom :<




time and manpower standpoint.




       Different pipe lor:- of




the  trench,   metal  toning wires j^hove  the pipe,  and color




coding the pipe itself.

-------
3-     Vacuum Otafeicjo.



       Vacuum stations  function as    transfer 1'aci "I i i.y

between a central rrci.Jlwct3.rm point for ail 3 vacuum  sewer

11 nes and a pressurised line 1eacl:in9 di rec11 y or i ndTKer:11 y

to a treatment facility.   Tl'ie following components

included :i n the vacuum sstati on (Figuft51 7):
       *     Vacuum p urn PS
       *     Sewage pump:-;
       *     Generator
       *     Collection  tank
       *     Reservoir tank
       *     Pump r:eintro3ss
       *     Motoe control  center
       *     Gage^/chrirt rocorrier
       *     Fault monitoring system
       Vacuum pumps are  needed to produce  the vacuum

necessary for liquid transport.   The operational history of

vacuum rsewers indicates that the optimum  operating range i

16?0  in.  Hg.   The pumps,  however,  should have the

capability of providing up to 25-in. Hg as this level is

sometimes neeeded in the troubleshooting  process.

Duplicity is a minimum  requirement with each purnp capable

of provi.dirig XOO percent of the required  air flow (cfrn).

-------
 CONTROLS AND
   ALARMS
I    I TELEPHONE
I	1   ALARM
 STANDS
GENERATOR
      VACUUM RESERVOIR/
                      MOISTURE REMOVAL TANK
        T AIRCVAC VALVE
              SEWAGE COLLECTION
              TANK
                                                     VACUUM PUMPS
                                         DISCHARGE
                                           PUMPS
                                                                      V)  VACUUM GAUGED
                                                                     VS ) VACCUM SWITCH
                                                                      C)  COMPOUND GAUGE
                                                                          VACUUM RECORDE
                                                                          SIGHT GLASS
                                                                     N.C.  NORMALLY CLOSEC
                                                                     N.O.  NORMALLY OPEN
TREATMENT
 PLANT
                                       Fir.URF 7
                                     LINF
                                          I IF A
                                TYPTCAI  VAIUIUM STAT I TIN

-------
       Vacuum pumps may  be  either the Ii.qui.t1  ring or si idin




vane  type and must be capable of delivering  the specified




cfm at, 20 in.  Ha.  A liquid ring vacuum pump utiliz.es a




service liquid as a seali nci rned'i urn het;ween an offset.




impeller and the pump r:aa:i ng.   As the impeller rap::i ns;,"~'Lht--




sservi.ce liquid is forced against, the pump outer cas:.i nvs by




centrifugal force,  and  a:i r i.s compressed and forced out. of




the discharge pipe by the  eccentric l.i quid action.   The




vacuum is created as more  a:i r i drawn in to be




compressed.   When liqui d ring pumps are used,  rvi 1 is




recommended as the seal liquid.   Since the service  liquid




continually circulates  when the pump is in opereiration,  a




service liquid tank must he provided.   The tank should be




corrosion resistent and air tight.   The tanks are vented




with  an outlet to the outsi.de.   Since the service liquid




carries a significant quantity of heat away  from the pump,




a heat exchanger is required.   A liquid ring pump i.s shown




in cr:iss-secti.on in Figure  B.
                               i'J

-------
       .Compound
         Gau
               Heat Exchanger
                               In   Out
                             Cooling Water
                                             Drain
                                                       Gas/liquid
                                                       separator &
                                                      service liquid
                                                       -I  Shut Off
                                                        \vaive
Make Up
                               FIGIIRF e
                          LIQUID RING PUMP
                            CRDSS SECTION
       S.1 idi.ng--van=>  type vacuum  pumps  may a I f,i \ kit*  used..   For


these types of.  pumps  an air filter is required.    This:


filter is located on  the  -inlet  line between  the reservoir


tank and  the vacuum pump  KO as  to rernnve particulate


material  which  might  Otiuse  excer>ivi-  nmpeller wear  it  it


were to enter the pump volute.    The urse of  si i.da ng-van


vacuum purnpn has -inoreaKed  recently.    The reaon  for thi 5?


i.  the lower power nnnrsumptn on  required for  a given pump
                                  10

-------
capaci ty.   On the negative si do,  the re  have been prob 1 ems

reported with the vul.nerabi.lty of these pumps should liquid

be carried into them.   In  this situation,  the pumps are

usually  damaged to the  point where a replacement pump will

be repaired.   By contrast,  the liquid ring pump,  by Tits

very nature,  can usually withstand an accident, of this type

with very .little damage.   Design precautions,  such as an

electrical I y control.! ed plug valve between the collection

tank and the reservoir  tank,  can be added  to the piping

systecn in order to protect the slidi ngvane type pumps.   A

cross section of a slidingvane type vacuum pump is shown

in Figure 9.
                           Fll-illFJF  9
                       SI ID TNG  VANI- PUMP
                         IIROSS  SFCTTflN

-------
       ^ewage pumps are required to  transfer the liquid that




 is pulled into the?, collects.an tank  by  the vacuum pumps; to




 its ultimate point of disposal.   Dry pit pumps have been




 used extensively although submersible  sewage pumps located




 on guide rails within the collection tank may be usetT'rtS an




 alternative?.   The rnnst frequently used type o1: purnp have




 been the non-clog type.   Duplicity  is  required with each




 pump capable erf providing 100 percent  of the design




 capacity.   The level  controls are set  for a  mini.mum of 2




 minute:;:  pump running time to prevent excessive pump




 starting and related increased wear.   The pumps should have




 shutoff  valves on both the suction  and discharge piping to




 allow for removal during maintenance without affecting the




 vacuum level.




       Check valves are used on each pump discharge line or




 on  a common manifold after the discharge lines are joined




 to  it-   Equalising lines,  consisti.ng of small diameter




 clear PvT: pipe connecting the pump  discharge to the




 coll ecti.on tank are usually required.   The purpose o1- these




 equalizing lines are to remove air  from the the pump and to




 equalise the vacuum  acrossed the impeller.   Tn acldi ti.nn.




 they will prevent the "loss of prime should a check valve




 leak.  Since thi.s ;setup wi 11 result in a small part of the




discharge flow being -recirculated to the collection tank,  a




decreased net pump capacity results.

-------
       fterrone 8r Associates, ri..n  thei r  mast. recent designs,




 have eliminated equalizing lines  by using horizontal, sewage




 pumps with a con tin ou sly flooded  auction.   This is




 accomplished through the use of a ball  check valve on the.




 pump suction pi ping between the collection tank and tTie




 sewage pumps.   Prior to using this concept,  the d?si gner




 should carefully weigh whether  the pumping cost savjngs are




 significant enough to risk the  posr-iibi li ty of failure of




 the  ball check and the resulting  problems that would occur.




       Sewage pumps are typically  located at an elevation




 significantly below the collection tank to minimize net




 positive suction head (NPSH) requirements.   l.n conjunction




 with NPSH requirements,  pump heads are  increased by 23 feet




 to account for tank vacuum.  Both vertical  and horizontal.




 pumps can be used.




       Materials  of construction for pumps include cast iron




 with stainless steel, shafts,  while avoiding aluminum,




 bronze and brass.   Fiber packing  i.s not recommended.




 Double mechanical seals which are adaptable to vacuum




 S6?rvice should be used.




       A standby  generator is a must.   Tt. ensures the




continuing operation of the system i.n the event of a power-




outage.   Standard "generators that'have  been used in other




wastewater applications are available from a variety of




manu facturers.
                              13

-------
       The wastewater is stored in the coj.lection tank unlvi I




a  sufficient volume accumulates,  at which point the  tank  in




evacuated.   It is a sealed,  vacuum tight vessel made nf




either  fiberglass or steel.   Fiberglass tanks are generally




more expensive,  but do not require the future maintenance




(painting)  of a steel tank.   Vacuum,  produced by the vacuum




pumps,  is transferred to the collects on piping system




through the top part of this tank.   The part of the  tank-




below the invert of the incoming linos acts as the




wetwe.11.   A bolted hatch provides access to the tank should




it be necessary.




      Most  collection tanks are "located at a "low elevation




relative  to most of the components of the vacuum station.




This minimizes the lift required for the sewage to enter




the collection tank,  since sewage must enter at or near the




top of  the  tank to insure that vacuum can be restored




upstream.   Many times this results in a deep basement




required  in the vacuum station.




      A vacuum reservoir tank is located between the vacuum




pumps and the collection tankl   It has three functions: (1)




to reduce carryover of moisture into the vacuum pumps; (2)




to act as an  emergency reservoir; and (3) to reduce  the




frequency of  vacuum pump starts.  H..ike the collection tank,




it can be made of either fiberglass or steel.

-------
       The? vacuum pumps  are  control led by vam.itjm  swi tches




 located on the reservoir  tank.   I lr.ua 1  operating  level  is 16-




 20in.  Hg with a low  level  alarm of 14-in.  H:j.   The sewage-




 pumps are control.Led  by a probe( ft) located inside of the




 collection tank.   line method includes using s^ven (77"




 probes,  one for each  of the six (J) set points of the




 pumpii no? cycle and one (1) ar, a  ground.   Another  method




 relies on & single probe  that is capable of monitoring all




 at  the set points.   ThwsG* probes are the capacitance	




 inductive type.   They require a transmitter/transducer  to




 f.end  a 4-20 mA signal to  the control pane.1.




       The motor eonto!  center houscK all of the  motor




 starters,  overloads,   control  circuitry,  and hiourc> run  metv=r




 tor each vacuum and sewajge  purnp.   The  vacuum chart




 recorder,  colllecti.on tank  level control relays,  and the




 telephone dialer are  also normally located within the  motor




 control  center.




       Vacuum gauges are used on all  incoming lines as  well




 as  on  both the collection tank  and the reservoir  tank.




 Their  purpose is to allow the operator to monitor the




 system.   These gauges are very  important in the




 troubleshooting procedures.    Chart recorders for both the




 vacuum pumps as well as the  sewage pumps-are needed  so that




 system characteristics can  be estahli shed and mrmi tared.




Like gauges,  these  recorders are vi tal  in ^the




 trxiub I eshooting process.
                              15

-------
       A  fault riionitar'inci system is  neerh-fd to  J f-fK"t  the




operator o1r  any irresgul rities;,  such as  a low vacuum




'level.   An automatic telephone dialer ;-;??rvr-?s  t.h.is




Th3Ke 
-------
 t
                    In addition to these spare parts, there are certain

              specialty maintenance tools and equipment that are needed.
                                        TABLE 16
                              SPECIALTY TOOLS AND EQUIPMENT
L
                          1 ea.
                          2 ea.
                        100 ea,
                          3 ea.
                          2 ea.
                          2 ea.
                          1 ea.
                         15 ft.
                          2 ea.
                          2 ea.
                          1 ea.
                          1 ea.
                          1 ea
Portable vacuum pump
Portable vacuum chart  recorders
Vacuum charts
Chart pens
0-20" W. G. magnehelic  gauges
0-50" W. G. magnehelic  gauges
12 VOLT DC submersible pump
Pump discharge hose
No-hub torque wrenches
Vacuum gauges
Flexible mercury manometer
Controller test box
Pipe locator
                   The vacuum station also requires spare parts.  These
                                                         _. . T-^.'-rrfs'-'rr*..
             range from spare pump seals to fuses.   Specialty iterns that

             should be considered are:
                                        TABLE 1.7
                                   SPECIALTY EQUIPMENT
I
                         i
                         1 ea.
                         1 ea.
                         2 ea.
                         2 ea.
                         1 ea.
r
U
Inductance -probe    '   .
Probe transmitter
Probe microprocessor card
Vacuum switch
Vacuum gauge
Auto dialer microprocessor  card
  10

-------
      Especially  vital  far-  the vacuum  station are  spare:-..




microprocessorbased  electronic  components.  This  type  of




equipment is used for the level  controls  and the fault




monitoring systems and  is very sensitive  to power  spikes.




These system components are the  two most  important parts  of




the station, as they  essentially operate  and monitor  the




system.   Losing either  to some type of failure will cause




short term problems,  such as loss of vacuum or discharge




pump malfunctions.  Not having spare equipment amplifies



the problem since this  would result inr the system  being




operated manually.  This would require an operator on a




continual basis (until  the  spare part  arrived) to  cycle




both the vacuum pumps and the sewage pumps manually.

-------
II.   VACUUM SEWER SYSTEMS




     D.   SYSTEM DESIGN CONSIDERATIONS

-------
                      SECTION   D




S_Y_S_I_E_M	Q_E_S__G_N	C_Q_N_S_I_0_E_R_A_I_I_Q_N_S_
             Q  3 i. 9 n  E. 1 1! w s  an d T h e T. r V n r i a h j_ 1 ;i 1 . , i g r,
                            AVFRAGE DA 1 1  Y Ff.flWS
            I- unclfiinFjntii^l t.o the derva gn  nt" a r-uvwr-?r =!yr:t,i?ni  i:-;




     hhft dftt.nnn.niiit:i.i:in o1" des.i gn f:"l ciwr;.   An  a'l .I tiwarir:> nl" 10O




     g^'ilonr?  pev i-:;\ipl.t.ii--day (Qpiod) h.=ir tiFfen  nr-u-'d  =ii=i a




     !3t;;nc''j'al  r"i,i I *~; in  t-.he?  design  ol r:nnv(fnt."i rira I  F;I->WWK'F;




     J3ys:t.e?mn,   HOW^VF-K', t.hafc gRn^KV-i I  rule- may wl'lriw 1:or mo'




     i n f-i 1 hrtion than mf\y occur when  vac:uuni ?;-.ewers etK-w




     iiKp-d,  and it. allows  For some amount of  t-.imimere-i 1  and




     industrial use  that  fnay not be present  in vaouurn r:ewer




     design.    Experience  with vacuum  sewers  has-shown a




     lower  allowance  to he more  in order.   If available.




     water  use records should carefully he analyser! and a




     per capita use  established.




            During the early stage:-: ot:  pressure sewer




     development,  extensive ~i nveslvi gati.on were made into




     domestic  water  consumption  during periods of  ~lnw




     outside water use. with the r.-orrel ati on that  water




     consumption  would closely parallel  sewer flow.   These




     stud.i es showed per nap.ita flows rangi ng from  4() to GO




     gpcd.   Flow  measurements wre made on convent i tm.-il




     sewers serving resd dent:i.al.  commurn ties  during pr-riods

-------
 eye ].(> <"J"i scnarge,  and  an av^n-aon?  l.i.rne  p:r-'l.l-.;i net)  of  n'




 eccmdn,   a  vacuum  vallve Mould  tie requi red  bo  ripen and




 c'J nse ">'H  times  in  a irri.nube,   wi bh  a  "repst."  ot: only about,




 20  seconds  hebween r:yc I *-?.    Tl'i i :-; may  noi.  pr'etti^rit, a




 fH'Cit"i!Ltf;in  t,o  a vi I ve t.h( I a L'i vc-; l.y  oliipji-- t.n  t'.hc--




 vac:uum Kt.sihi on,   nonnpct.ed  ho a tt"  ina.i'n..    A  d i 1"t"ernrit.




 a:i t;uat-.i on  exir->1,r;  t'or  ,-i  v I vw ;-il,  tvhc:?  far frid or  l-,h'-




 syKl-ern t.hfit,  :i r-:  r:nrm Fr: bud  t.n  a  4" infHii.   V. ir:uurji  t- f>;-ip( in:;




 ( tl*=?  atri'I i i'.y of  t.hiP' vacuum  main  t-.n ciuick'ly  ror: ivi--r  l,o




 l-.hw r-^airu"'  Iwvel  of  vacuum  bh=ib  pxi r--.bi~'d  pr-i or 'L>'i  hl'ii-




 cycle) it;  n1" ab&jo I u <".= :i.nit.>"iKt.ani':i=! :.i n  vcic:uunt  SI'-W^K*




 df-:si gn-    Vacuum fr-:pnnF.e  "i P:  a  1:unr:t.i cm  of  '1 i nf  length,




 p"i fi(>  di.amRt.wr,   number c-if  r:onruvr.t.i.onj-,,   and aniiiunV.  erf




 '1 i f\;  ~i n  t.h  sys:br;m.




         fihotjl.d a  ?;i btuvibinn  ex"i.fjb bhat  is  causf  .-f-or




concern,  t.hvi--nb




backups  until, the  val.ve. 'i M capable ol"  empl-.y i ng  bhe




bank.

-------
                                 NI-S i UN  I-1
              'lgri  f I OWFJ ;=IK<^  maximum  flow  rati.'  -"'xper.:td t.t i

 occur onci?  OK" twi <";*>  P<;?K  dd  to  nixw  thf--

 vacuum  sewwr  inairiK .ts w~' I 1  ,i th*--  various  vacuum

 f.tial- 1 nn  r:ninpnrient;;-"s.    Flow K-at.c-vr-i  in i-'xnt-'nr;  r>f'  dr-'Si gn

 flriwr; can  i tr:r:ar  t.inrler r :*=( 'i.n'i ri si t,uH t/i cms  ( SP-T.- I 'r<=T,r;uKt

 ^^|..wf;:r ::wcl,irin,   t;l*rt s  manual,  I I

 rj=-'?:i gn  1" I nwr;  'should  nnl.  hr-  S,.-ikr'n ;:if.  tihe tTiciximuiii  1V1 nw
         in i:\r\ft PKewsufff  Si-'Wi-r  Kc-'nln on ot  tKiif.  cn.=ni.i.-i 1 ,

Rnwrm  d"*ssi'.:K "i hi;>:-; var'J .oi.is  r:>t.url i i\';-;  of  1:.l.ow v-*K'tujs

w:turi v<:iT <-?nt  dwe'Lling unit,:-.  ( fiil)!.)' r. )    Ttd.s  LK  araj >!'t:i r;

O
                                    :i n  Kriapher  [J.U  ol'  Lh.nt-.

s<"M-;t,ioru   Uowne deve U ipert    f-fquc-ita.an  for  fffshii maUi ng

design ("'low  basi?d on  hhe number  of"  I-IOIMOK  t.o  hr=  K

This  fquatri on  i.s  as fVil 1 OWK:
                            O  =.  AN  f  B

                            Q  -    Der-ign  flow  ( gprn )

                            A  --  -  A r-oef-^lci.ent.  psel ecfc^H  by
                                    f* f\ 
-------
 h.        M'iri i JIIUIM  l::; I ow  Vw'l ric . j_L i w;--.  in  I ''i (:>>.;









           The  herrn  " !=!!= I i:  r: I t^ani n3  vi--0 oni.hy "  r<   .-< ! rtrii..i  wi l.h  l.!-u-




 w.'-iLi-^r   riar'c 'i <:JK'..     In  mari nt..'ri~i n  an  i.inoh';i'.ru< rl.c-'rl  p:i pf  I n n<->,




 t.l"i.-i1,  v<~- 1 1 in.i t;y  fvjhrnjlrJ  t:t^  sul""^^ i~: i on I",  tvt \.r cinr-r't"^"^"  ;:;ir i 1,




 t.l'irtl.  rn'iy  \w  pir^KPrit  ri n  t'.he  w<-if-;tii;'WFii-.c";K ,   i.n  rn-r^vi^rri.




 ojct-'awiv  pl.'iLincj nn  t.h*--  r:r~nwn  ''5>(.it>|::u-'nrl  pr:>v"i nun l.y  s^hi'.l.f^ti  in.'i'ht.r-'K..




           Jn  hl'ir1  Pri^RMUf't"'  Swwprr  si:>r:t. i <"  nnnclur-'.T nn  rc-'ar:hc:'i1  i r:  i.hai:. tl'ir-




          i-'d  rninnnium  ve'l i n-.i hy  1 ' cir  sr'T 1:  n!l i--.'iri-i n:i  ) :;  ',-'  t-.ri  3
          V->loc::i t-.H err--,  i.n  i-.hf  typical,  vacuum  ar'wi -K  range




        15  tn  >B  fps,  ohvj nusly  w^T.l   .tbovw  hhi--  uri n.i




                     ne.'l t1  el,** an in a-     A  r:rirnrnnn  t:l,^im  f>"
haK  n(-'ve'   hen  a  h I ockaae  reported  :i ri    vac




ytr-'in.     This  may  be  fl  K-.3t.hftr  st-.rnnr? r: I a j MI ;  hnwi-*vr-r.




the  high  transport, vwlnci t,i. *???  fiUflW^f-'t.   I. hah  hhc




pr ribahi..!. i hy  ; rf"  h.lnc:ka3<3s  or;i::ait-"K"i ny  ;-n'f  i

-------
           i (.1'. :L 1. L- :< b is V.'  L" !'J U. S t-. J Q D f~
          An understanding of'  thr- vaniiiini   l,i-'anr~port  pt-'nr:<-T.r.




i '.-:  needed  hy  the  ;~:yr;1>'fri  dew i <3n<-;r_    With  tht-?  r-;aw  hrml.ti




pro1"i.J *'',  and  a;-:; II on '.3  an  no  vacuum  v;-i 1  vft: .-ire




oporftt. in<3,   nri  Kifw-'^!:.!'-'  l.f.:mr:piir't.  1".."ik'<-r;  p ! .-ir:r?.     All




r:(-';wT  t.lic





pi pr?  'in  thr-?!i:<  nt'.at. i ':  rinndi t;'i cins,   l-il.t/h--  vacouiri   Itisr.    f i nw
                                                                           a t. r;:-:
                                                                              i.hr--
 is;  (-ii":r:umi rig.




          Wh*=n  a  su1"'f "i r:i erit.  vnli.inir-  tit  F,c-'wa'.:3O  af:r:




 | n  the sump,   l.h,e  var:ni.nri  VH 1 V^J r;yc: ] t'j..     I hie




 di ffp't'enti aJ   pcef;r;nt- f  t.h.tt.  r-x-i :;!.:>  hc-l,w'^n  t.h




 main  and  atjnowpl'u'K-f--'  l:riK<::cw  thf-*  t:;urnp  r:cnhpnt:w




 m!"in.    While  ar::r:ol,ef-'vit.:i ng,   l",h'  y:wwa3r-J  i '"  KMpxd ! -




 LKnnsf ofrniffd  i.nt/o  1;i:;>ai(i - arid  ;rmn  nr:r:up i.p*r>  only  p.^r i'.  i-ihui-n  he )>-.-; tv-r




 iVom  t-.he  air  to wateK  t.=keK  pK^n^e  J.:u-"3i^ly  hhKfiugl'i  tl i"j




 action a1;  sheaK Fjti-sr-:r3.     "1 he  numrn tude*  ot  i.hr--




 prnpulfsive  forces  starts tri  der: I :i rn-'  not i i-rwnh i y  whi^n




 the vacuum  vil.ve  r.'\ nse  hut  remain 3 rfipi'irtant  ..i:: thu




air continues  to  expiand  within  th^ P i P:J     I- ve




 fri.oti.on  anrJ  gravity  hr ~i ni^  th;  FH.'waci-f  to  r> -.-: t




r-;piot..    Another  va I v<;^  i:yi:le,  at  any  1 oc:.'it. i on  upstrea




ot~  the low  spot,   wi II   c:ai.t :>  thlv;  st-'Wtigr-1  to  i":ont>i.nJi"*




"its movement  toward  the  vii
                                                                             I  I y




                                                                             ci  low

-------
           vVir uiiin  rjyr-'.l.i-'in:;  ,irr-  i !<';; i  "iru-'d  l.o  i ipf -r a l.i   i in  tvwo

pbiHsr--  i i  r  t.i i  liquid t'lnwK  wi.t.l'i  t.bi-a  .1 i r  h*'? r nci  aririri t,hid

frit-"  .-I   l,"i  rnc-'f  pf?K"t ucl   l,wi or-  t,l'iit.  o1:  l,bi-   I i qui.d     llpt>n   tyimr-

ot   1.1'n-1  A I I^VAII!  va I vr HK <"i<^ JuKh<:il;il i . ;   hir-ru :(?,   v.-ifi nus   ciif1

t.( i   1 i -:|ii i  d  K'at'i nr-v .;n-"c.'  at.l'.a'i ru-ib.l f.p
                                                                              ^-.
          Ni irtna I  I y,   i.he v-ir:uiini  puinpf-;  ,-ir'i   .;i.  t.i i  npt-?r^i.e

i:n-> !',wi"'r-'n   IH  and l?O"i.n.   H<3  in f  v.-u ;i iurii.     i'l if.-  m i rvi mum

v. irn.d.rni  ill  1 1- i - "i  n ..  Hn f'-'SJU I t.r;  .in   .4  t".ot'."i I  iiv.ri l.::ibl<- hr.-.id

 It inn  i"i1-   '1 t'i -f:t--'^t,.     FT VR f-f.-i-.-t  rif   t.hi F-.  I-M .-td   I or. p.  -i p.

r r-f<::|t i i Y r-d  t'.n  npi-VKVit.e bhr;  vara.iurn   valvcf,    I f.iv i n:j  1 3--f-( --t,

,-  a-h   hh<-'  v,::ir:uum  st.at. ion
                    ( tvpi :"! 1  1 V  j.6--in,   l-<<3  wh i   ii  '"(' ' " I -'   IB-- "hi.    cif
                       tr.^K )
          Vv  =    Vacuum  f-"f=?r)u:i r't'-'i  bo  npofa t.t--  i.i"i??
                    (ft- in-   Ho
          WH hh  Vc:    fit-ati.f.  LI'IMJ-"  +  FK-I e.-h i on  I i i;-?r;,   and  t.l"i

           vailuwf?  juwt'ist.H t.ut.Pd  'in  fcl""-  .'ibovi-1  ftcjurttion,   t.l 11"?

       , i nn   i r>  s'i mp 1 1 f i ed  t;o:



                    fit.atir; !..O::K  f  f-r i..:t.i <-in  l
-------
                              l-'-igure  1 O  i :-i  

-------
       Static  losses are  those incurred by unring

 lifts,  or vertical profile  changes.   Profile changes

 are accomplished by usdng two 4H- degree f ri tt"i ngs

 joined by a section of pipe.   For efficient USF* of

 the energy available,  profile changes  shou'J d he s

 small as possible.   Numerous  lifts are recommended

 over  one large  Iri ft.   Table 1 shows the recommended

 lift  height for various pipe  sisres;
                          TABLF 1
                  REnflMMENDED  I...TFT HEIGHT
                         Liffc-Height
                           1. 0 ft.
                           1. 0 ft.
                           1. 5 ft.
                           1. 5 ft.
                           2. 3 ft.
            3 in.
            4 in.
            6 in.
            8 in.
           10 in.
       Static losses  are calculated by subtracting the

pipe diameter from the lift height (Figure*  11).



       Static Loss =  Lift Height  - Pipe Diameter
     4/Vvc SOLVENT
                                       l?Hr STW1C UFTFOK
                                            CMUUOM6 UNE
                                            LOSSES - UFT HBQHT
                                            MMUS WE DWCTER
                                           -ran AU.PVC SEES.
     SCHEDULE 4O-WW
WELD. 
v nnwes
                         FJfitlRF 11
                STATIC  I OSS DFTERMINATIUN
                         10

-------
       Fricti on loss charts  for SDR 21 PVC pipe  and  a


 2:1.  air/liquid ratio have been developed by AIRVAC,


 and  are contained in their  design mamual-   Friction
                                                  *-.

 1 riwses are nnly calculated  for sewers that are  laid


 between 0.2% and 2. 0 fa 1 .1.   Fri.c-;ti.on !.| ns-srjp-s  in l-wTLr;


 greater than 2. 0% are t.o he ignored.


       The friction tables,  along with the system


 nalculation sheets,  will give the designer a


 conservative result,  since  the calculation sheets


 assume all  flow inputs; occur simultaneously resulting


 in a  cummu I ati ve flow rate.   In reality, this? will


 rarely occur.   Because of the anticipated nature of


 the  system flow,  some engineers have totally  ignored


 friction  losses in some past projects,  with


 successful operating results.   Despi te this success,


 ignoring  friction losses i. not recommended.


       The hydraulic calculations should commence


 including friction,   A separate calculation can then


 he made to see how much of  the total  loss is  static


 versus friction.   Assuming  proper line sixing has


 been  done,  some liberties may been taken with respect


 to friction  lasses,  depending on the particular


 characteristics of the system..   This should on.I y be


 done  by those with vacuum design and 'operation


experience  and in no case,  without written approval


of the manufacturer.
                        11

-------
                      Ouii l.dio.9
       The geometry of a  vacuum sewer system :i F;

si ri 1 ar  to that of a water  distri bution  ssyrat.Rm.

Rat.ht-fK" than looped, howvwr,  "it; ri s nnrinaVly ~i.n A

dendf ;i f CIKHI pat-t.^rn.

       Tfr. .Is des'iK-ah'I.R t.o have the vanuum st.a*vi nn

lacabed  as centrally as  possible.   This  lends  itself

to &  system with multi-branches.   This is a very

important,  ar> multiple main  branches to  the vanuum

stat;-i on  give added operating flexibility.   For

example,   with a system having 3 branches serving 300

customers,  the worst case soenerio if; that LOO,  or

one-third,  nf the customers  may be without service

while  a  problem i.s corrected.   By contrast,  the worst

case scenerio assuming a  similarly si.2*ed system with

one branch would have all 300 customers  out of

service.

       When laying out a  vacuum system,  the rtesi

should select pipe runs  that:
      *      Minimize lift
      *      Minimise length .
      *      Fqualixe flows on  each main hran>:h

-------
       The?  length  of  on I ler:tiiin  lines; .in-"  c)< vt=?i ned by


twn factors.   These  are sta tic  .I i ft and friction


losses.   As previously d"i s":ussed,  tho Ruriirnahlon  c;rf:


these two  amounts yeru^ra 1 ).y cannot exceed 1.X 1"=?et.


Due to ^estrfti ntr> planed  upon ear:h rir?j?i gn hy
                                                     *.

topogfaphy Hnd siswajae 1:.l owr-;,  it,  i.s i rnpossi bl.e to cri v


a definite maximum linp; length..   fine opt-ratri.ns Kv^l.^i


has a s:i ngle main  l:i ne hranch wx>i~t


in  length.


       Vacuum s=w*?r design  fulejs  have been develo


largely as a result  ol" f-.tudyins'-T  opRKat'i.ng syf


important  design  parameterra are  shown in  the


following  table.
                           TABI.F. 2
       Mi.ni.mum distance between lifts         V?0  ft.


       Mini.mum distance of  0. '2.% slope         50  ft.
       prior  to a series of lifts


       Minimum distance between top  of         6  ft.
       lift and any crossover connection


       Minimum slope                              0. 2%

-------
                                    TAR! F :<
                                      I NFS FUR
4"  Mainw
                    6" Mains
                                     * -   , P%
                                     *   fif ound (3.1 ripe
                                     * -  flO% of pi fie rid n
                                          ( between J :i f tr. on Ly )
                *  -- 0. 2%
                *   (5 found r.l.op*=!
                *   40%  of1 p-i.pn di
                                                           nn 1 y
       Tahl.e 4  nhnwa at what. li=>ngt.h  t,h ().*<''' eater  than 135 ft.   0. 2% s3 ope


   Less than  10O  ft.       40%  of pipe di..

          f  than 1.00 ft.   0. 2% slope
                                  1.4

-------
       ATRVAC has dwve.1 oped a  table rr:orlr|l
                                        ~       " ........ ~~
                                        150
                                        54ti
       Substi tut-.ri ng the  values  nf maximum flriw  (O)

from  Table 5  -i.nt-.n Bowne* s jni.rnp] i f led  equation,

(Q-. 5NH-'
             than 70.

-------
        The valutas  in  Tab IP* I-J  ^should  l:it-j  uwc'd f nr




planning  purposes or as  a t-stoiKti n3  p.ii nt.  f'or  th*




detailed  design.   In the Latter niise.  est/irnatwrl




speci f'S c  f'l.nw inputs* alcmy with th= 'f;r-;i cti <"n  tatile




j-hou'ld kp? used 'in the* hydraul i.e.: ':v-i l.c:u l.atii.nns.     A




r;orrer:tly si^ed line will yx.c-> I d a n^lat-i vo I y  small




t'K"i r:i;j nn  "Loss.   '[1%   when gni.ng  tn thiw  next "I Nr'ger




p i pf=?  si^e frinti.nn ] or=ss  is cri gn i f i nantly  rwducr-d,




Line  was  mrist likely unrtr->rsi '^t?d.




        Experieni:::e  has shnwn that thrrj  is  little




econorny in using  3i.nch  pipe for  riiai.ris.    For   thif;




reason,  4inch is thi? mi.ni mum recommended  main  si z
                             Iti

-------
       In most cases,  vacuum sewer  mains are located


 outside of and adjacent t,o the edge  of pavement and


 approximately para I J.el to the road or street,  which
                                                  **.

 reduces the expenses of pavement, repair and traffic


 control.   in areas  subject to 'unusual, erosion, the


 preferred location  is often within the paved area.


 This location is  also favored by some muni c i pali ti es:


 as  being an area  where subfiequerit  excavation  is  I esr--.


 1 :ike l.y and more controlled,  arid there f~on> ,.i tot ration


 more protei-;ted from  damage.


       fine of the  major cost components ot" a v.-ir;uurn


 system is the vail ve  pit setting.    With two or more


 homes sharing one setting,  overall system


 construction costs can be significantly reduced,


 resulting in a major cost advantage.   To do this,


 however,  may require the main 1ine to be located in


 prj vate property,  typically in the back yard.   There


 are  two disadvantages to this type of routing.


 First,  it requires permanent easements frnm the


property owner,  wh'd ch may tie dn f fi.cult to obtain.


Second,  it will require the operating personnel to


venture onto private property during preventive and


emergency maintenance,  a move which  may not be


particularly welcomed.   Ihe designer  should careful.ly


consider  the tradeof f of reduced costs to the K ici a I


Issues  prior to making the final routing dei :i s i on.
                         17

-------
       An advantage ho  the aftt* ot vacuum r-;t~'w<">rr;  I.;';

 that the small diameter  PVf'l pipe used is flexi bio and

 c:an he easi.3 y routed around oh star.::! e.   Thin feature

 allows vacuum sewers to  foil 1 ow a windi ng path as

 nr*cir!Sry.    '!>if pi.pe shnu3.fi tip bent in a 1 ong K-ad-i t.is
                                                    T'-r
 if-  possible,  not in a  radius  ls   than that

 n=fi:nmutendpd  by the pipe  manufacturer.   In the

          section nf tha c manual,  Bowne prenents an

          from the llni -Bell  Handbook of PVI ; Pipe in

 which the minimum radius of  bndin
-------
       1 I'll-.- separati on of vacuum sewers  from water

supply mains and laterals  often requires the vaci

sewer he buried  deeper than  would be required for

other reasons.   In  most instances the  separation

requirements are dictated  by state health

departments.   These requirements may vary from state

to  state.   A table  from the  Pressure Sewer section  of

this  manual rthows typical  requirement:::: for sower

'.line/water  line  sepa.ti.an.   arid is repeater! below:
                           TABLE 7
                    TYPICAL REQIITREMENTS
                              FOR
        SFf:'ARATri)N  OF SEWER  LINES FRl IM WA.IER I TNES
Parallel           Locate sewer as far ias  practi.nal  from
ins ta'l 1 ^ti ons     water main.   Minimum  Keparat'i t m "1O
                   feet-   rf  sewer is r-.loser than 1.0 feet
                   from wateK  main,  sewer  "it: to he
                   located 12  inches lower  th.m tl'ie  water
                   main.   In  some jurisdi r.t. i ont-~.. wl in
                   closer than  10 feet,  sewer T r> to  hr> nf
                   water main  material.?;  or  ennfirswrJ.
                   Other jurisdictions allow water and
                   sewer dn the same trench if the sewer
                   is  1.2 inches lower.

Crossi rigs         Crossing is  to be as  near! y
                   perpindicular aK practical-   Sewer  to
                   be  12 inches "lower than  wati'-r main.
                   Some jurisdictions require that no
                   joints he  imed in the sewer main
                   w:i thin 10 feet of the crasssi r>g-

-------
        Prrit i I ?if\ of  the mains should  always  tn:' shown on




 the plans.   Slopes,  Vine  si ;res and  lengths,  r:u"J vert  and




 utility crossings,  inverts, and surface  replacements




 are typi call y shown nn  the prot'iI.es (See Sf*r:tion B).




        Cul vwct. and  ut;-i'1 ::i..V.y crciss'i ngn c'll'fcftn  di (:1-.^l.f





 nurnr^KouR vari at/i ("inr; 'i n  t;l"ie dept.h n1: hur.i al  ot" vacuum




 sewer  mains,  with,  many  K'su'l V.i nci Ka!.ti'T arid  ;->ummri t'.r-; in




 the? pipeline  p>K'nf:i. I e..    1 In'l :i ki-.1  pr e:~;nure mrcinr-;,  whi-'n-  ,-ri K




 acc:i.imu!l ate:?;  at a suuim:i t t-f cit.ii.ri ng an  air relwa(-> vt-ilvr-.




 vacuum sewwrs  arp  nnt a'Ftwctwd  hy hri gh pni.ntis nn th^




 pfofxTe.   The-?  sags,  however,  may pren^rit a  pKoh"! oni,  a:-:




 they typically w:.i "LI. add 1 i ft to  the systwm.   Fn




 addition,  if not dorn gnt--d and  r:nns;trijr:tcd  prriperly,  .=>




 Kag may  tf-ap* sewage at  I rw  f low  p=rinds blrmki ng o f-f




 the low  part of the swwr.   When vari atinnss aft*




 regarded  a detrimental,  reaches of the vacuum sewRr




 main may  he placed at a particular  depith tn allow for




 the crossing w.i thiout using  a lift.




        To  minimd.Tre  damage  to the  vacuum newer main




 caused by subsequent excavation,  route markers are




 sometimes placed adjacent to the main,  warning




 excavators of  its  presence.   Accurate  asconstructed




 plans are helpful   in identi-Fying the  pipeline location,
               *                  *



and a cable buried  with the main can  be induced  with a




 tone so the main can be field located using  common




utility locating equipment..

-------
        A  warni rig  tripo marked "vacuum  sewer"  "i'.-. r-oineti tm-'r;


placed sha'l low Ly in  the pi.pel.,i ne  trench  ho  -further

notify excnvwtors.     When  thr*  tapp; :i n p'l .-iced  1 nwi--K  :i n


the  tffnch,  w. 9- ,  adjacent to  t.he pipe,   at  Is; ru="l led an
                                                             ^p-,
"id?nt~i f l.cat"i cm" tripe.    The tap<;>  nan  h>";  mtali.xftd nn :i t


can  hi-- d(=t*3f:hr-d  with iiti .1 i ty 'locating devx;eK..   Most

bap*-':>  nannot. he  i ndur-.ed wltl'i a  bone  .-it. a ni gni 1~i r:.inh


c1=rpth,  so  rnetali.^i^d  tapi7? should he pi ar:t?d ha'l 1 uw'l.y to

tip; di?tnctr.'d.   Jt :i F;  also vp^Ky  important  to  rnak^ sure


thf=-  tapi^ doer; not  be>oome folded or twisted  during its


FI'| acwmrant  or  the detectable surface  arr-m will hi-?

rednoerl.
                             21

-------
       Trenching may be accomp.1 i.shed  ussin3 a



wheel  trencher,  or chain type trencher.   The cho:i r:e air

                                                 *(,.

equipment is usually dictated by  the contractor based



on  the material to tie excavated as well  aw topography



and available working space.



       Imported material  termed "pipe zone baekfi I ~l " js



often  planed to surround the main several Inches ~i f



material  excavated from the trench is regarded  an



unsuitable for use as that material.   Pipe ?one



backfill  is usually granular,  such as pea gravel or



coarse sand.   Fine sand or soil is' generally not as



desirable as it bulks,  rather than flows,  into  place



under  the pipe haunching.



       The remaining backfilH material required  is often



specified by the agency controlling  the  road or street,



especialy if the mains are located within the pavement.



       In  some cases H lean cernent-sand slurry is used



for backfill.   This option i.s particularly attractive



when a trencher  is used,  the mains are located  within



the pavement,  and prompt restoration for  traffic
                             '*


       ] is  important.

-------
                              IE RIALS
       PVC or A8S thermop} astic  pipe ace riorrn.'i I ly  usi-ri

 for vacuum sewers.   In certain  cases.  DCIH has  also

 been used, assuming the joints  have been tested .m<1

 found suitable  for vacuum service..

       The most  common PVI"! nia'ins are* Iron p i p*=* i 7I5-

 (IPS) 200 psi working pressure  rated.  st.i;ndrd

 dimension ratio 21  (Class 200 SDR  91  PVC).   Cl,,ss 1 t'-U),

 SDR 26 PVC has  ulso been used.   From a pressure

 standpoint,  the lower class pipe is acneph.-itij.o.

 However,  thinner wall pd.pe is more ".likely to be damaged

 during installation.   Further,  there is Little  cost

 savintgs between SDR 2H  and SDR  2f>  when the excavation,

 backfill,  and surface restoration  are considered.   For

 these reasons.   Cl  200,  SDR 21 is recommended..

       PVC pipe  hao a high coefficient of thermal

 expansion; about TH/8-i.nch of length variation for 100

 feet of pipe per 10 degrees Farenheit change i.n

 temperature.
                                         -5
       Coefficient i n/in/oF =* 3. 0  x  1O
       Considerable  temperature changes wi1J he

experienced during  pipeline ri nstal ~\ ation, and some

degree of temperature change will  occur rluri.n:i

operation,  with climate changes and effluent

temperature changes.   To reduce expansion and

contraction induced streirsses, flexible elastomeri o

-------
 joint ("rubber" ring"  joint)  pipe i preferred t.o  be


 used.   If  solvent wejded joint pipe is  ur;ed,  the  pipe


 manufacturers: recammendritinns  fur i nwtaT 1 at, inn


 rr-^ardi.niqi  hf~inper:it.ure trjcmfjidefat.innR nhould be
                                                    *TV

 tn'i:i owed.   The l.lni~8e:il. Handbook ot= PVC Pn.pe a f r?o


 pK-rivides: gu:idartr:e as  to proper pract.lcen.


       In the  past,  the f i ttri ngF; mowt often jr-~.ed were


 the  pso.lvent-wel d.  Drain,  Wa^te and Vent (OWV) type.


 These types are more  common3y  available than ganketed


 joint fittings (one major Line component,  the wye


 required "for  each connection to the main,  i r-? not  even


 made  in gaskefced PVC).   Expansion and contK.-ii :ti on,


while a concern  if the entire  system were  so..! vent-


welded,  are allowed for in the main Tine pipe joint.;-,


which typically  are igasketed.

-------
                              i.s a  rnnv^ t.nword -j'J Inn nr-it.'i ng  all


olventwelding.    At.  J.^asst, rrt:< one majoK- 1:-i t;l;i ng


manu1~a<":t,cJK4K  is  oon;=H rt^K"! ng  making  9^s-;kl;d  wyc


fn.ttings.   Unt.il  thri r;  happeriK,   sornr-? ricintract.iirs  an-?
                                                              *-,

urging  Kp'Lgot,  adapt.Kr;  (an adapter fit.t.ri.ng  l-.hai.  r:rin h*


si"ilvent. wRldf-fd :i n  a control .1. ed  envn fonmnt, ini.o  ach nf


i'.hf thin^F*  I r*g?i n1:  t.he  wy r'tnnul hinfl in  a Ofrirskr-l.^d Jn i ri 1%


at.  each nt- hhe t.hrrje  1 -?g;- (Figure 1V)..
                       SPTGC1T ADAPTOR DETAII

-------
          Vannum  sewer  nervi ce  lines run "from  the varri.umi




 ma in  to  the valve pit;.    Typi '-ft '1.3. y  these  line*?, are  near




 and  parallel  t.n property  1 "i np-c-T.    'If  ei ther  the  v.ilvr--




 p:i t  or  main  tine  i :-:  nn private property.  t,l -IP?  f5Pf v i i :>-.-




 "t i n<^   I i kowi ne will   ti=f  on  pri.viihf* piTpr"t,y.




          Ft.  in grind  prorrtvi i~-.e>  t;i"i  hnldl y  ^i * I iJ nwrk  t.h^




 loont.'inn  rr|- t,l-iw F5ervi.r:F-  line  wi t,h  properly  .:i fierrl. i t"i r'l.i




 l.-iV,l"i  i:i  t;w  days prior  l%ri  -i risl-a 1 I. at-.i.nn.     1'h i n  rai^rvePJ :=!




 a  reminder  i;<~ t.hie prnpRrhy  ahrmt". hhe i nt,-nrjp-d iin.vtlvion




 'md infty n^usw t.r'i*-* prriFirt;y  nwnc?r to  rftnrngni y.f.i RMrnw




 rif.-.=ij;3on  thfit hl"i*^ lonati.on   Kf'ni'iu I d  be  changer!     'j I. nl PSI-I




 f-Terver:  as? an  ridvannp? nohi.r:^ to nei.ghhors  i f  property




 liner? arc* in  douht.




         Mrmt;  muni CT pa I i hi er-;  prel"rr loc*tn.nsj tl-it--- F5t-rvir:o




 l.i  n  whi^rp-  it will  not he  driven  ov^r.    Othi-;r:;:,




 how^vr-r,   prwtV-?r lor:atiny  t.hft  srtrvi cf I  i.nR within tht~-




 paved dri..vewriy.     I hi? r^asnrri n<3 i.s tht  RufciR^quent




 t?x::cvflt.xon  and  a SKoni.fitted  riania'.^t-' to  t,lr\f> :-;r-i-"v i i :: IT <  i -,
                                         -*



 I.RS  11 k=-l y  wi thi.n  the paved  < :t,n on.




         Sr"v i.r:i=;  1  i nc.'R  should  he  "loc.ated  dn.r.t;-mt. frc>\n




 potable  water  lines  to reduce  the poi-:sSi hi I :i l.y i it or or* p.




 r:cm taini riciti on.    I  l"i<^y r?bnu1.d alrso  be  dxr-at.t-mt  f-roni utiii-r




biu-ied utilities?  it1  possible,   dee to  thf--  prisi kii I I ty nam .t 




i ir  repair  of   t.i"iot~.<';  ut'i j i ti ef-"s.

-------
       A31  connect.! ons to the ma .in, r; I led crossover

connections,  are made "over the top"  (Figure 33).  This

is accomplished using a vert:i oa I. wye  arid a long  radius

elbow.   Due  to the restraints placed upon the depth  of

sewers by  the connecting sewers entering "over "the

top", engineers should consider the ground cover

required on  these connections at the  design stage.
                               9O
                               TURKJED
                                           WVC.
                                          Ttr
                         FIGURE 13
               CRfJSStlVFR CONNECTION DETAIL

      Table 8 gives  design parameters when lifts are

required in the  service line.
                           TABLE 8
      Minimum distance from
      lift to valve  pit

      Minimum distance from
      lift to crossover

      Minimum slope  between li.fts
5 ft.
  ft.
2 -:i n or
0.2% (Larger)

-------
            ino lines typically are ;'(--inch in diameter.

 An exception  to this occurs when a buffer tank i s
                                                   **>.
 used..   Buffer hanks are used for large  flows which  wi II.

 result in  frecjuf^nt valve cycles..   To mai.nta:in grmcl

 var:uum rr-^ponse at, the hijl^fef tank,  a fi-innh servrit^e

 1 in is
       The UKF?  o'f r:ha:i.n  type  trenhhec-R is  nortn-'t:! ines

speci-fd.ed for  service .line installation where n:i I.

types allow as they r:ause lefsR dn sruption  to thr

property owner* s yard than does a  hackhoe.   Rnnky SOT Is

and  some clayey sod Is that will not self clean from the

trencher teeth may he impractical,  to excavate using) ,-<

trencher.

       Street crossings are often ar:r:orftp"l ished by the

bore  method :i n  which an auger  is used and  a  steel

casing is pushed in  the refsultincj  opening  under the


street.   The casing  acts as a  sleeve for the service

line  that is installed inr-nde.   fit her"- street crussi n

are  "free bored"  by  the use of a "hog".     Open cutting

of the street  is  done where boring is impractical.

-------

        Service lines  in vacuum system;-; are huri i?.''j a



 rninirmjm of 30 i nches,  since  tr.he vacuum line that exi ts



 the valve pi t, does so at a depth  of '?7~i nches.



        if a trencher  i FJ u;sF*d,  t*ir;rid-i ng nnd hackfi 13  is



 ussua'J 1 y native m.^terla"!  t.=i k*:-'n i~rnm the trench



 exr:avi=iti.on-    When th :-~.ervi f.c-t l:i.nf;?s arw  :i nta!l 1 d tindt'



 tr\=i veiled way OK- when rnnk  f-.'xc:"ivatlrin 'i  en< :ou n I. e ('>? rj,



 snm:njnd"i n3  the rjer-vi.i~:e 1 1 ne wi th -i rnpn;n''ted F<::i pe



 bar:k1-l 1 i.s  advi sed,



        Many nnntreictorF1. UPJO a hankhoe I'nr t!-ie se



 '1 :i ne excavation.   The rear-inn For  thri F: i sample;  a



 backhoe IK reciuT.red  1:or the  excavatinn rrF the  valve pit



 whi r:h  typically i.s located clnwe  to the  main sewer.



 Many times thi.s rer>u"ltK in river excavati on" of  the



 service line  trench.    Over-excavation,  coupled with the
                                    /


 use of  fittings which are typically required between



 the valve  pit  and main,  is a recipe for  future problems



 if  proper  bedding and hackfi.il I  material  is riot used.



       Since  the native material and intended contractor



 equipment  i.s  not  always known,  it  is recommended that



 the contract  documents specify surrounding the service



 II ine with  i reported pi pe vane backf 3 '1 "I -
       As  with the vacuum sewer mai.ris,  Class ?00,  SDR 2'l



PVC  pipe  typically is  used for the  service liners..



Solvent-welded  f)WV fittings are used,  although  rubber



ri n
-------
 c.      Build i rtg__ Sewer 









        The term building sewer refers  to the  gravity




 flow pipe extending  from  the borne to  the valve pit.




 setting.   In  many cases.,  state or 'local  authorities




 regu Late installations of building newer?;..    "I l-ir? Uniform




 P l.umbi.n5 ("Iridp i ?; often ref ererined.




        For res:.i.dent:J a 1  pservi r:i,  the building  sewer




 shou.l.d be 4~inr:hi and fi I.ope r:nnti.nouFsl y  dnwnwnr-d at;  




 rate of not  less thn  1 /4i nr:h per foot  (^--perrrent




 grade).   Desirably,  the valve pi t setti.ng should foe




 Donated near  thie hnnie  so  the hui.il di ng sewer  i s short.




 wi.th j,esi:; need for mnintenance and 'I er?R  opportunity 1:or




 i..rif i..ltrati.on.   l.:i.ne  si.. Tie  for cominerci.a I.  users w:i. 1 !1




 depend on the amount of flow,  wi.th a  minimum




 recommended si.zre of  6-i.nehes.




        Fiends should be  avoided in  building sewers,  and  a




 cleanout  used for each aggregate  change  in  direction




 exceeding 135 degrees.




        Infiltration via leaking building  sewers has  been




 common, as has the connection of  roof or  yard  drains.




 A quality inspection during  homeowner connection :i'.>




advised to determine if  these situations  exist.   Tf so.




 steps  should  be  taken  to require  their elimination




prior  to  .final! homeowner connection..  "

-------
         To minimise the r i <:k  i>t:  dam.'igie  hi i  t.h: 1::i herciJ a??:;




 valve  pit,  during  homeowner  connecti on  to the system,  a




 stubout pipe  rrf  rsu ff:i rri erit  I erngtvh ( typi oa'TJ y




 I'i1:eet)  tVorn the  valves p:j 1.  -is  r i^fMimmRndi^rl.    Tri





 convftnt-i ona I  ijKavi hy Kwers;,  F T'A  e i i >:<:.! tn 1 'i t.y ends  <::*t




 t.he  wyw,  with  the* ^Kavrity ;-:wrvi r:^ pip*-- hen rig f*n




 pi ni---!-j..ci:i h"l.<-?  i t-rn.   I I'lt"- fioint^  r't^wfjorrinq  won.Id Hiigi^enb i.h.'-il.




 f.-1 'i ciitri.'l 'i.ty ;i ri  a  v
-------
3.     Valve Pit Settings
      a.
            General
            The premariuf actured,  fiberglass  type of valve

      pit setting is by far the most  common.   This type of

      setting is comprised of four main  parts;  the bottom

      chamber (sump),  the top chamber (valve pit),  the

      plate that separates the two chambers  (pit bottom).

      and the lid (Figure 1.4).
                             FIGURE 14
                        TYPICAL FIBERGLASS
                         VALVE PIT SETTING
                             32

-------
        Wastes  from  the  borne  is transmitted >'>  the  sump

 vi a  the building sewer.   This sewer  enter; the* sump

 "Itt"  above  the sump bottom.    Up  to four separate

 building sewers can he connected t.o  one  r--.unip,  each  at.
                                                          -.
 9O d-!3^ees tci one  anuth^r.    A t.=i(:if*rt?d sl'i^ini--  IK (.ir-ii^rt


 to f ac:i lit.atR the  btnrrklH 1 1 iri;^ pKru-:edi.(KR.

        The  r-:umps have a wall  thi <":)-'nt. h=f.i s^hts ;


 H()-::i nchies  and 5fi4i.nnhwf?.     Both  HK'^  IH i nr:hijc:  in


 di anif ter at the bottom and  HH i nchew in  di ainr-'i-er  at


 the top,  with the  smaLler sixe  hav:i.n<;( .=i  capacity  of


 55 gallons and the  larger one lOO-ga'l lonr:.


        The  valve pit houses  the  vacuum va J ve  it.Fielf.


 Tt ip  manufactured  by  the filament wi.ndi ng f.i.tartrglasr?


 process  with  a wall!!  thickness of i-J/1.6" and is

 sui table for  H20 traffic  loading.   The valve pit  ri K

 36inch  diameter at the  bottom  and i.s i:nnir:af1y


 shaped to  allow the fitting  of a  ?'3  1 /'?  inch diameter

 clear opening  cast  iron  frame and cover  a I. the top.

The  depth  is  4J?inches.   line >*  :i.nch  diameV.er opening,

with  an  elastomer seal..,  is precut, trr accept.- t,h*--  H--


i rich  vacuum pservice line.

-------
cleb iron
        The pit  hot bom  i r-; made ot' reinforced f:i berg I awr>




 that is  1/4" thick nt the edges and 5/1 h""  thick  in




 bhe center.   Tl iese bottoms  are molded by  bhe resin




 inject process;.   Valve  pib  bottoms  are provided  with




 hoj.es precut  for the !'-(--i noh suction line,  4 inch




                      f  arid bhe sump securing holt,




                      ,ween the  vaj ve pi b bobbmn ami hi n">




                       fie.Id using a wilicone or butyl.




                          I l'ii-a pi i. bottom has  ft lip which




                    pit  bo r-; imply rest on top ol" it.




                   ;.ov<"'K T!  and  frames;,  desi gned 1 cir  HV'O




 traffic  loading,  nee  l.ypical'ty used.   ihe  it




 weight, is generally HO  pounds and tl-ie 1 H d  w




 about 100 pounds.   When .=> Lighter 1 i d i.r-> de;~.i red,




 such as  in nan traffic  ?; i.hi.iat.;:i ons,  a I i ghb weitght




 aluminum  or  cast  iron 1 id may be utsed.   These byper-:




 of  lids  do nob have frames,   bub rather are fitted t-.o




 bhe valve pit through the use of two .f-bolts.   Thetse




 It.ids should  nII ear I y he  marked "Nan Traffic"




       A shallower  arrangement is possible,  if so




desired  (Figure  15).   This arrangement would he  ur^ed




in  areas  where high <^roundwaber or  poor soils exist




and depth of the building sewers are very  shoI low.

-------
                       TRAFFIC OR NON-TRAFFIC
                        , COVERS AVAILABLE
                                            MASS CONCRETE
                                          FIBERGLASS VALVE FIT
FOUNDATION BLOCKS (4)
          S" SUCTION UME
                             FIBERGLASS SUMP
                      FTGURF  IS
                SHAI.LflW FIBERGLASS
                VALVK  PIT  SETTING

-------
       Certain  situations call "for  the use erf concrete

 valve pi. t settings,   These are described :i n labile 9.

                          lABt E 9
                  S T II I AT 1 1 INS THAT I) T CT ATF
       *     When  the deepest fiberglass setti ng IPS
             not sufficient to accept  the building
             Wt'ien  .'H  'LaKge f Low 'is
             requi.K3 no  1"1riw
       *     When an  Interface bet-.wftp?n  two system
             typt?  (e.g.,  pressure and  vacuum) is
             needed.
       The deepest  1L'i. berg]. ass swttd na ir.  8 feet deep.

The  building sewer depth at the vaTve  pit setting. is

therefore Limited  tn 6. 5 feet,  since the bui l.ding

sewer  enters 18-inches  above the bottom.   Should a

deeper setting he  required,  a concrete? val.ve pit

setting may be used.  The maximum recommended depth

for  a  concrete pit is .10 feet.

       These type of  settings are typi.call y

constructed of 4 foot diameter manhri "!. sections,  wi th

the  bottom section having a pre poured 1.8 i nch

diameter sump (Figure .16).   Tt as very important that

all  Joints and connections be water tight to

eliminate groundwater ri nf i U.rati.on.   Equally

important 3 s the need for a we'1 1  designed pipe

support system,  since tl-iese tanks are  open from top

to bottom.   The support  hardware should  be of

stainless steel or plastic.

-------
                                                          STErPS
OR MORB
  ALUM. PIAMONP
  ME5H PLANK W/
  SgRATEO TOP
         WORtvl
                                                FL&XI&L6 PLASTIC
                                                PIPE 3CTIOKJ9
                                                W/
                                                TOP  BOTTOM

                                                COKJC. F-IUU
                          FT.GURF 1.6
                       TYPTCAL C11NCRE1F.
                      VAI..VE PIT SETTING
              Earla.er in this section,  t=,he ystem hvdrauli.ns


        were discussed,  with the senral  conclusion that  1.H-


        feet of  sysstem loss wa avan 3 .atil.e;  13-f-eet for  the


        collection  piping nd S- feet fnr  the valve


        operation.   The S'feet generaJ !l.y  corresponds to the


        amount of" !l if t reciuired to evacuate the sump


        contents, assuming Lhe deepest fiberglass valve pit-


        setting  is  used.   Increasing this amount wri It result


        in a decreased amount .war I.ah I e for the collection


        system.  Depending on the specific location of  ths

-------
d?ep fsetti ng required,  thus engineer  may opt to serve


the home  by other" methods.  Should a deep concrete


setting still, he the choice,  the engineer' should


receive written approval of the manufacturer.


      For  large 'flows that require attenuation,"'a


buffer tank should be used.   Buffer  tanks are


typical! ly  used for schools,  apartments,  nursing


homes,  arid  other" large users.   They  are designed with


a small operating sump in the lower  portion, with


additional  emergency storage available  in the  tank.


      Like  the deep concrete va'l ve pit  settings,  the


buffer tank is typically constructed of 4-foot


diameter manhole sections, with the  bottom section


having a pre-poured 18-inch diameter sump (Figure


17)  The same water tightness and pipe  support


concerns apply to the buffer tank.
                        FTGURF 17
                    TYPICAL I::UNI::RFTF
                       BUFFER TANK

-------
         When  an  i nter t'rico  between  two system  typej-t  -in

 needed,   a duaJ  buffer  hank  should he  used.    For

 example,  a  hybri d r-;yf:ti-'iii may tie  uwed,  with  vacuum

 r-:ewers J-jervin;::! t^l'ic  cnn.jrir'i t'.y til'  t.l'ie  r-:Rf-'v:i r-.e*  aK'e;-i nnct

 pKeKsuK"e Kewer;:;  er'vi n-;^  t'J'u-1 1~r "i n^e?:..    A1. snnie  prrint.,

 a 1".r;-inr;l tion wi. I.I  he ni->f.diVfi'J hi-jtween iA ie  pr't-^finure  t 11 iw

 and  vacuum  f I ow.

         A  dual  hu 1  1"er  t,.=ink rip; wi mri \..&r~ bn .1 ht.i1:1-e>'  Uanl--,

 with the exnephi  on  i.hah  it  i R   I af^eK  tn  annnrnndr^l.e

 two  vacuum  vaJvef-; (Figtire 1H).    Thes;e tnk;-. typically

 uti.il-t7p  5-toot  di arnet.ec  nu:mhn1 e  Keoti..nns. .
                                t- I liURf-  1 H
                          TYl'ICAL IXINCRFTF
                          DUAI  HliFF'FR TANK

        Dual buffer  tank may  "l.r.n  be  used  if  the

single  buffer  tank doeri not  have  the capacity  for  the

large flows.    A si.ng'l H  huffer  tank har: a  '.:U)  gi

capacity while a dual, buffer tank has  a fiO g

capfiici.ty.

-------
b.
A P. E> y.  fe  Q tJ Q C- K '2
         Antit I ohrit.i i.in  r:o I 1 fir Ft ;HKe psometi HIPS?;  uned  on


the  'Fi.herciJ. i-iRp;  v.*i'.]vw  pit.  swhhi ngr;  (F'igur"7* "1H)-


B(~iuy;-inc:y I':;H I nu I rit. i nns sshmLtld bin  done  ho psi^i-1 "i 1: l;h=fy


."if-;t:  Hxpftfi^nnfi  has rthnwri 1-hah t.he^f3


on.11 .'IKS  ar  uruial  ly rioi1.  n-v=dpd.    Should l.h^y  be  used,


,-;;=,r-p, mijp.t;  be  taken  duri.np)  the  v.'il.ve pi 1% i riKfca!!'l.afci.nn


tUF. ponr-  bidding rind hankf i 11  may "lead to  sett. I ernent-,


pt^ob.l enifs.    Set.V, I enent; of  t>he  i::oncKet.e K:inj:j  rno?5t.


"I :i ke I y wi.11  resuTI t  in damage  to  the building  a


and/i IK  l-.hr--  pit  i tpse'l -f.
                                 F1RURF  1R
                   ANn:-Fi..r.riATThN HOLLAR
                                 4O

-------
 a.      General









        The AlRVAH  vacuum valve oper.it.es  wn thout the




 use of e I ec;t.ri.ci ty,    I hi"' valve j ss  varxiurn operated  tin




 open i ng and  sprang /.IKS is ted  on closing,   Sysstern




 vacuuin pnsurt?f; pa si. t:i ve valve seal.-! rig..




        'I he val. vws  hav  a H--i nr:h up^na n<3  and arc-1 rnricj*--




 i:d  scheduJ.e  8C) ABS and h.nve  stai riles a sstRFj'l  Khat-fcr.,




 dw'l K"Ln hear"! ncjs =ir^d 13!! .-it-;l-omi->r ae=i1,PJ.  The va I vw is




 equipped wi.fch a rn] 1 "i ng di.aphK'.:rim t.yp=f vanuum opf^ra hor"




 and i.s capable o1* civt^crimi ng all r5a1inj 1'-<:in'.5: and




 of~  opening us"i.ng  vamium iVniti tl'ie downst.K'eani  S3 d nf




 the valve.    All maherd al.s of t.he valve  are r:hieitn.r:a!l ly




 resistant,  to sewage and -i t-tr.  gases.




        The  control iFtr/sensnr  H.s the k=y  r.ompnnent of




 the vaJ.ve.    This  nlevioe re I i.er-i on  three foroes for




 its operation: pressure,  vanuum and atmosphere.   An




 the sewage leve!l  rlrses  .in  the sump,  it  comprwssns  air




 in  the sensor tube.   This pressure initiates the




opening, of the valve  by nvercnming r-ipr:i.n3 tension  in




 the controller and activated a three-way valve.   llnce




opened,  the  threeway  vr I ve  allows t>ie




controller/sensor  to  take v.nr-uurn from"' the d
                            41

-------
side of  t,he  valve arid  ctpp.'I y .it  to  the  a<.;t-.ua l-rir




chamber  to fu'1 l.y  open  the valve..    The




contro Ller/J>enor i.r-i capable of  iriai .ntan n:i IT^ f,l"iv  v;-i 1 VP




1:u"l !l y rifii'fn f:rif  n  fixed period  of1 t~d rni-\  whi r:h  't ::




.'id Juoi.ati I R nvi=>K" a range  rif-  ;-i t."i  1 ()--t;si-nnnds.    At:l.-r




t.hf;  time  pe.f~i.nd KHS  wlappsed,  atmi'irsn't'iefir  air  :i f;




adnri tted  to  the actuatrir  chamber pfrnn tt1. i n;::| r.:prina




assisted  c'ltising  n1-  the  va'lve.      All  materi a I r: rif the




r:ontrn I J,er/sensor are  1:nbri.cated frcnn  ft pl.aKt.~ir:  rK




elashnmer that  :i r. chemir:a'!.it.y resistent  to  we wage and




ri.ts  gases.




        Two typen of" vacuum valves are ava'i "I ahl e:   hhe




Model. D valve  and the  Model  S  valve.    I he val ver?




are  physical l.y  identical.,  but  re.ly  on  "H d i 1~"tT;reri t




pi pi ng/pJ.umbH. ng arrangrtrnerit  for  the-j *-'  wm-rct-'-  of




atmnspheri r:  ai.r needed for  proper  controller




operation.

-------
             MI. inn  ..i) ..VAI.VF
         As  fit.fltF'fl  <=?;:ir I :i.ei--,   nne  of  Ivhe-  t-.


rtsqurJ red  1:or t'.hc~; prop) >r  cipt^rat.xon  <'if: t,


is  atmossphi^ri r: ;;rj r.     I l*uv>  Model  15 vft'l v*


at,mosphr'i r:  a'i f  i-.hroue^  wh i c-.h IK


an  external  tin at.ht-'K   pi pi-;  (t-ifi(nrp?  x?O).
                                                  F>  cr>nt,r r


                                                     lvK  t;FiS.
                                                   r:onn (-.:
      BREATHER DOME
      LOCATED ABOVE
       FLOOD LEVEL
ofuvrrr
    w HOMES
         rsucnoHUNE
             ^          I  I Gt !RF  VO

                      MODFI.  0  VAI VF

-------
       The Model  0  valve .is  the most. reliable type




since  there is lit Kile nhanee  of water entering the




con trailer.   However.,  some  dilike this;  type of




arrangement her: a urn-- of aesthete as.   Some 1:ear




vandalism o1n the external hreather,  whiof'i would have




a detri mental 6?1~fei":t on system operation.   Experience




has shown that these are B^tTQeiyed proh'l ems,  rather




than actual prob'l erm-;.
                         44

-------
                   Ml IDE!..  S  VALVE
        Th Mode]  S  valve  is a  "ssumpverited" valvf=-.


 One  of the three r:<-inhra"Ll.er tubes  is connp*cbf"'rt t-.n  hhe


 c.leanout./Kt3ni3nr pn p:ri..nc|.   Th:.i s  pi.pd.ng Rxt-ends :jnt;r>  t,he


 lower surnp,  whxch  is connp?ct.d fco  the? hui l.di.na


 sewer.    The kiui.'Lding sewwr is  open  fco atrnnspherir:  air


 through  the 4 -inch auxiUlary  vent  (Figure i?1. ).
                                              MASS COMCftETE
         OMVTTY SEWERS
         FMOM 14 HOMES
                            FTlqLIRF  21
                          MJIDhl  S VAI VE
I" . f

-------
       While el.'i.Kn nating some of; the concerns




 associated with the external breather,  the  Model S




 valve  has potential problems of its own.




       First,  it is absolutely necessary that  the sump




 be  air and watertight.'  Should system vacuum  he' XWFSS




 than 5"-Hg,  for whatever reason,  the valve  will, not




 operate.   Sewage will continue to fill  the  surnp..   Tf




 the surnp  is watertight,  it will become  pressurised,




 with a "bubble" of air trapped at the top of  the




 sump.   When sufficient vacuum is restored,  the  bubble




 of  air will be used by the controller in the  valve




 closing process.   However,  should water  completely




 f i.l 1 the  bottom pump in the same s< :enerio,  the  valve




 will open  and stay open since it will lack  the




 atmospheric air needed for closure.   This open  valve




 will cause a  loss  of system vacuum,  which may affect




 another valve at a different location in a  similar




 fashion.




       Second,  the  installation of the homeowner* s




buiding sewer becomes more critical.   A belly in the




building sewer will trap water and riot allow the free




flow of atmospheric air.

-------
       Some engineers have experimented with a bl.end




 of  the two concepts, by utili ^ing  a  breather that




 gets its air from th fcQB chamber.   This has been




 successful  i n areas where there  i s rm chance for




 surface water to enter the top'nhamber.   The rtangef




 is  that water may enter the  top  stmip f i 1 ling it to a




 level  above the breather.   This  water will di reotl y




 enter  the controller and cause problems with valve




 cl.osure.




       In either the Model 0  or Model S valve, water




 in  thw top  chamber is of1 no  concern,  assuming the




 controller  itself is watertight.   To prevent water




 from entering the top chamber has  proven to be a




 difficult task-   For this reason,  venting from tht=




 top- chamber is discouraged.




       Changes in materials,   pipe si^es,  and supports




have resul ted in a more aestheti.cal 1 y p1.e?asi ng and




 vandal proof external breather.  Because the Model f)




arrangement is less susceptible  to problems than the




Model  S.  it is th=? recommended type.




       Since the two valve types  are  physically




identical,  it xs possible to cnnvrt from a Model S




to a Model  D,  and vice versa, with little effort.
                        47

-------
h.
       The external breather has heen  d:i.snuB^fcfi n the

previous section.   An early version of this included

an  1--1/'P" gal vanri.zed pipe  xt-,Rndi ng 2 t.o 3-f-i-.  above

        near t,hfi?  valve pit,  setting  (Figure 2.V)..   A

        r dome*  is; needed t,o prevent c. 1 riga'i n<3 IVom

small  insects.   This size  ol" pipe was neoewwary  for

it  to  tie self  supportiriig.   Tri addi hi.nn,  :i t was

thoujght to tie  less susceptibJ.e to damage.  This

arrangernnt haK been successfully used in many of  the

operating vacuum systems,  a 'I though some perceived

prob.l.erns with  aesthetics and vandalism still exist.
                         FT (JURE ^T-J
             PARLY  HXPERNAI   RRFATICR DFTATI
                         48

-------
                        Some  engineers have detai. 'J eel an external


                  breather  that uses small*?*" diameter galvanized  pipe


                  (typically  3/4").  This pipe, and the breather  dome.


                  is  damped  to a  4" x 4" past that lr; driven into the


                  ground near th=?  va'l vw pit settinpt (F'i.jjmri* 'A'A),    Th;i;


                  fsli ves  the arrangement a more permanent look,  while


                  also adding protection to the hreather.
-4X-4 TRCATEQ
PO^T
"TOP
                            Z'-C" MIM.
  LOCATE
OUTRIDE.
    CXCAV'M
                                                                       1-IN&
                                             ATTACHCD TO
                                        FIGHRF 93
                          ALTERNATIVE F.XTF.RNAI. HRtATHFR DFTAII.

-------
        AIRVAC  allrao o-fferp: i'n cnlor a I sn

 t.n i tss  appearance.
                     .     FIGURF ?A
                           AIRVAC
               ALTFRNATTVF FXTFRNAt  BRFATHF.R
       No matter what,  arrangement. -IPS  ued,  two  Items

require attention.  f-ir^t,  the ent.ri.rr-? p-ip-ing sywtwm

from  the dam*? to the  connection at the controller

must  he watertight.   Second,  the piping munt slope

toward the valve pit  swtt.i ri<^.

                          FiO

-------
                 AUXILJ.ARY_VFNT
       A 4-inch PVf!  vent i.R  required on the  building

sewer.   The:  purpose is to provide  a sufficient amount;

of  air  to ant as the driving force hehind  the liquid

that, is evacuated from the  lower sump I se  Chapter  I,

Swnti.rm G. 3. r: for a d;i . nus i on on  system operation).

Wi.th a  Model J:i valve,  a si?fr:ondary  function  is to

provi df-- the  nenenrr-ary atmospheric::  ai.r for  proper

r-.ontro'] ler operation.

       The auxiliary vr*nt i.c-~. made of 4-inch  PVC pipe

and  fittings (Figure 2S).    Most entities require  it

to  tie located against a permanent  structure,  nuch as

the  house or a wall.   To pirevent valve freezing in

cold cld.mates,  the  vent should be  a minimum of ?0

feet from the valve pit setting,  thereby allowing the

warmth  from  the newage ti me to warm the air.
                                      MCIURE OR fOST
                                        180 BEND
           COUP1MB

   FROM CUSTCUOt
                                     < MSEKWE

                                    < - 4BKMD
                                       ORMIY UNE
     rtWcusroia
___^  TOMOMf
                   F 11^11IVS ^Kt

            AliXll 1AIVY VFNI OF I All

-------
       To monitor  the number of va'lve  cyol.es,  a cycle




 counter is availabl e_   This device is designed for




 mounting directly  on the vacuum valve or  the va*l ve




 p:i t wain.   The unit-,  is enclosed ri r> a  watertight




 hour-ring wi th a clear nylon top.




       With this device,  a.t, "is por:r-j:t.h"l.e t.n monitor the




 number nf cycle?; of  a particular valve,   l~lyc:1.f>




 counters typically are utilijred where a large water




 use i.s expected in order to determine if  the valve i.s




 reasonably capable of keeping up with the flow.




       Some entitites use the cycle counter as a




 metering device.   Knowing the number  of cycles and




 the volume per cycle,  one can estimate the amount of




 sewage through the vacuum valve over  a given  period,




       Others use the device as a method of




 determining illegal  storm connections to  the  vacuum




 sewer,.   The flow through the valve can he estimated




 and compared to metered water use.   From  this,  it is




 possible to conclude if ex.traneous water  is  entering




 the vacuum sewer and generally in whi^t amounts.




       Tt i.s not necessary to have a cycle counter for




 each valve,  (unless,   of  course,  they  are  being used




 as  metering device for  hi 1 I.ing purposes),   s  they are




 small  and  can ear.:i ..I y  he  moved from location  to




 location.   It is recommended that the spare  parts




list include cycle counters.  (See Section  K. 4)

-------
Qiy.iion  Met lysis sod G3*@
       Division valves are used on vacuum sewer mains




much as  they are on water mains.   Plug valves and




resilient.  seated gate valves  have both tmen




successfully used,  although care must, he exercised  in




t.he selection process to insure Keliahi "H fr.y ( ?>ee




Chapter  F  of this Section for a di.scurasn.rin on parat




operating  prohlemr. with plug  valves).   typical




locations  for division valves are at branch/main




intersecti.ons^ at both sides  of a bridge crossing,




both sides of areas of unstable soil,  and at periodic




intervals  on long routes.   The intervals vary with




the Judgement of the engineer,  but typically range




from 1, 500 to 2, OOO feet.




       The  valves should be capable of sustain:!. ng a




vacuum of  24" Hg.   Contract specifications should




call for a certi f ied test from an independent.




laboratory to very this.

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       The body,  bonnet,  closure element, and  trun:ionr;




should be fabricated of  cast, iron equal to ASTM  A12fi




Class  8,  with the -.l.osure  element being covered  with




a precl.si.nn molded BunaN  facing to act as the




rersi ,l,.i ent seating surface.   The mating surface ~shou I d




he ninety (90%)  percent  pure nickel polished tr  a




fourteen  (1.4) RMS finish.




       Valves 4-inches and  smaller may be direct




actuated  while all sixinch  and larger valves should




be provided with gear actuators.




       The operating nuts should be of cast imn  equal




t.n ANSI A126 Class B,   The connecting pin or key




should  be stainless steel.   Aluminum nuts are not




acceptab3 e.




       The valves should  be installed in a valve  box




con-forming to local!  codes, with the operating nut be




extended  to a position where it accessible with  a




standard  valve wrench.  .

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                 Recent;  dec-signs  havf incll uded a  gauge tap,


          lo.cat.ed on the downstream side of the division  valve


          (Figure 26).    Its purpose is  to a] "low vacuum


          monitoring by one man in the  1:3e'l.d, ^.ithr'r" t.l'ian


          requiring two rneri (one t.o operate the va.lve  i n'"thp?


          "f':i el.d  and one to read the? vac-.uuin gc-i<3i-j at t)-iR  vacuum


          si.a tion ).
                             CAST IRON
                             VALVE BOX
                             * COVER
CIRCULAR CONCRETE
COLLAR (TYPICAL)

VALVE BOX
r x
CONC. BLOCK
VALVE BOX
3/r BARB    CA?
ADAPTOR W/ffl^
3/< FPT
COUP FITTING
     SOR-7 200
POLYETHELENE
1UBMC
                                                              MPT
                                                         COUP. FITTING
                                              SADDLE TAP
                                    F1GURF  ^fi
                                m: vis TON VAIVF
                             WITH GAUGF TAP OF-'I A [I
                                    HFi

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h.
f:!l eanouhw
       (Tj eanout.w,  called  accsf> prnnhs -in  vacuum sewer

t.ernrLno l.ogy,  have heen used in the  pa;-;t;..   The? if use

i.s  no longer  recommended,  KT nr:*=- accenH  t.ci tifF?  vacuum

main  can  b*-".1 gained  at. any valve pi \...   rJrnne fstahe

codesj may require ar;(::er-;;> paint.R t.o  he T.nt>t,."< I  I ed.    \f

so,  t.hey  should he  constructed as shown in Figure '?'7..
                           FTGIJRF 2Y
                     Ai:i:ESS POINT  DFTATL

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       Odors
       There are very few rdrir prohl ems reported w~i th  vacuum


sewers.    There are  three contri .huti ncj factor's  responssi hi e


for this:  1 )  the system is  Kepi "I ed, ? ) air n r-i i nl-rnriurred in


gr^ah volumes at each fl.ow  input and  H) det-.ntir>n ta mws .=                  *

1 K>  fps.   These factors result in a short detention times,


which also aids in  the prevention of  septic sewnge.

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n
        There if; one  except. "i ons to  the  above di rtcuss: i rin cm




 odors:  when concrete buffer  tanks are used.   Unlike the




 fi berg 1 ass settings,  these tanks  are  open  from  the  sump  to




 I. he  top of the pal;.   Operating perr-jonnp"! iiu.tf5t. br- canvl'ul  nf:




 SPrw^'f  gas  hulldup i.n l-.hesse tankr-:




 mc-ri nt.i=>nnoe*,  ajthnuyh t,he voluinw




 t.cinl< usually l.r, nrit', I i-ifge nriugh  t'.c~i prnrturin cJiincic-'K'! n.i";




 levels  of  l-iydr rigen  su.l 1'::i.de.    A.'lsn.  tJ-ir-'sr-? t.ypes  ri'fr tankra




 typ'ica'lly  a>'e  usswd  tn a tt,wnua I;P 1 afge 1~lnw^.,,  which  "11owr;




 t-ht?  K?Wci;3e ninre t.:i me t;n  t;urn  wepfcri.c.    I'hn r-5 drier; not  pr"efS=nt;




 a inajnr problem,  si.m~.fr> thte se?a "I c-?d PVl"! mains arr? tjni=i1"1"i=!cr:i',i"-'iJ




 by J5ptic  Kfriwaj^e.




       Al J  of the system  par-tvs &r& si hhwr PVi';, ARS,   I;NP,




 fubbef,  of shan.n].es53 st.F*el.,  which arw corrosi.on rp?:-;:i r-s ten t.




 Aes S5uoh.  ooc'rnsi.on  has not bewri a p^obl t-'in  i n vacuum  SCWRKC.




       The  accumulation of grease  i P; a  causw for concern in




 convention lift stations. n wel"!  as in some grinder  pump




 syst3m;3.    This  grease builds  up on  lc?vel controls and on




 the side of the basins.    Because*  the  puitipr- typica.l ly pump




 down to  a  point about an  inch above the  pump suction,  it  is




 difficult  to pump all of  the  grease frrim the sumps.    As




 such, grease traps-  are typically  r+--jqu:i.r ed  -i ri applications




 such as  restaurants  to prevent pump p i.uggi rig.




       Grease does not present, a problem  in vacuum sewf-'rs-




 Wheri the sewage is  evacuated  from the  sump, ' i,he ?;ur:r,i nn




pulls floatable grease into the vacuum mains.   Since the




sewage moves through  the  mains in  very high v1 -: i ti en,




there is  litt'le opportunity for grease to  Viu'i 3 J up  anywhere




i n  the system.

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       J n  Table  1.1),  nomerv: I nture u.ssod in the station

design if. given.
                               TARI F  10
                           VACUUM  STATTflN
                        DffS I I'-iN Nl IMENC;l._ATI
  Q  max             St,;it,iQn  pftak  1"1 nw  (y
  Qa                Station  .rivwra
-------
                 VACUUM PUMP  ST7TNI-J
To  Rx^e t.hf  vacuur^jaumps, the* ^n'l l.own nJ) fdrmu I a is ur-swd:
          Qvp=   A x  Urnax/7. 5  gal/1~h
"A"
                fs are  shown in  Table 1.1
                          1ABI.F  11
                         "A" FAHTHR
                         Fi:il? USE TN
                    VACUUM PUMP SIZING
                 - 3, oooft
           a. ooi~ 5, ooo ft
           5, 001- 7. 000 ft
           7, 001-1O, 000 ft
          10, 001-12, 000 ft
            Over 1.2, 000 ft
                                       5
                                       R
                                       7
                                       8
                                       9
                                      11
The minimum recommenrtwd vacuum  pump si^e is 1 FiO nfm.
                          60

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 r-                         To si.s:e  t;he  discharge pumps, use  the fol.il owing

 1      "              formula:

 [~                               Qdp  =  Qrnax = Qa x Peak Factor      


                           (Typical peak  factors range from  3.0 to 4.0)



                           The TDH  is cal oulated using the following

 j                    formula;
 i
                                 TDH  =  Hs + Hf - Hv

 i
 i
 i .

 ,.                          TDH i s calnuli=ited ur>in3 standard  procedures f>r
 i
                     force mains.    However,  ^^ead attributed  to overnomj ny

 i                    the vacuum in  the  noll.eotion tank (Hv)  mut also be


                     considered.   This  value is usually 23 feet,  whinh is
 r
 I                    equivalent to  20"  Hg (typical upper operating

                     value).   Since Hv  will, vary depending on  the tank

 -                    vacuum level (16-2O"  Hg,  but possitO to  operate at

 1                    much lower and higher leveHs during problem periods)

                     it  is prudent  to avoid a pump with a flat

 f '
 ;                    capaca ty/head curve.

                           Where possib'l e,  horizontal sewage pumper s^lO^J^l-^
 i
 i.                    he  used as they have 1 RSJK rsurrtion loesses  compared to

 r                    vertical pumps.  To  reduce the risk of  vortexing in

                     the collection tank,  the pump suction line should be

                     ?"  larger than the discharge line.  Sewage pump
L
                     shafts should- be fitted with double mechanical shaft.


                     seals with the sea!l  chamber pressurised with light

j--                    oi.l.


'-

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      Net pnssi ti.ve suction head ( NPSH )  calou1 ations

  e important  in  the discharge pump selection

process.  In  1 abl e 12,  nomencl.ahi.JK(=> used in the NPSH

calculations is given.
                            TABLE 12
                              ARriF PUMP
                  NPSH OAiai.H.ATlGN NOMFNOI. ATHRF
  Term__
  NPSHa"
  ha

  havt
  V max
  hs
  hvpa

  hf
  NPSHr

  heq
Net-, positive suction head available  (ft.)
Head available due to atmospheric pressure
(ft)
Head avail able du to atmrispheric pressure
at liquid level less vacuum in collection
tank (ft)
Maximum collection tank vacuum (ft)
Depth of sewage above pump centerline (ft)
Absolute? vapor pressure of sewage at its
pumping temperature' (ft)
Friction loss in suction pipes (ft)
Net positive suction head required by the
pump selected (ft)
Vacuum equalising head provided by 1"
equalising  lines (ft)
         Typical values  are shown in Table
                            TABLE  13
                          TYPICAL VAI.UFS
         Term	
         ha: .
           Sea level
           500 ft above  sea  level.
          1OOO ft above  sen  level
          40OO ft above  se.-=i  1 evel

         V max:
           IB" Hg
           20" Hg

         hs
         hvpa
         hf
         heq
                 Typical
                     33. 9 1-t
                     33. 2 ft
                     3?. 8 ft
                     P9. 4 ft
                     18. 1 ft
                     22. B ft

                      1.O ft (min)
                      0. 8 ft.
                      2. 0 ft (for vert, pump )
                      3. 0 ft (min)

-------

r
                             To calculate NPSHa.  use the fallowing formulas:




                                   NPSHa = havt 4- hs - hvpa + heq

                                   havt  =   ha - V max

                                   NPSHa must foe  greater than NPSHr  """




                             NPSHa and TDH should be calculated  for both the

                      high and low vacuum operating levels and  compared to

                      the  NPSHr at the corresponding point on the

                      head/capacity curve.
r
L

IT
r


C

L
                            Figure 28 is  a  diagram for  calculation  of NPSHa

                      in a vacuum system.
                                       hi - VMX
                                       (10.81)
                                      I
VACUUM TANK *
HIGH 20* Hg (22.6*
LOU 16- Hg (18.1*)
                                                          topi (0.78')


                                                          hf (*'}
                                                            NPSHA (12' 1o.)
                                                     _.. .. J:
                                                              ! EQUALIZUC LIME
                                                              WOt AT AU TIMES
                                                           SQWtt
                                               FIGURE 28
                                      NPSHa  CALCULATION  DIAGRAM
                                         WITH  TYPICAL VALUES

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J-


r
                          The operating volume of the collection tank is

                    the sewage accumulation  required to restart the

                    discharge pump.   It usually is sized so that at

                    minumum design  flow the  pump will operate once every

                    15 minutes.   Thus is represented by the following

                    formula:
                          Vo
           = 1.5  x  Qmin/Qdp x (UJdp - Qmin)
                          where:Qmin = Qa/2

                                Qdp  = 0 max  =  Qa  x Peak Factor
L...
      Table 14 gives the  value  of Vo for a 15 minute

cycle at Qmin for different  peaking factors.


                       TABLE 14

                     VALUES  OF  Vo
             FOR A 15 MINUTE CYCLE & Qmin
                                   3.0
                                   3.5
                                   4.0
                                       	Vo	
                                       2. 08 x Qmax
                                       1. 84 x Qmax
                                       1. t>4 x Qmax
                                           64

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r"
[
L


f^STt
      The total  volume of  the  collection  tank should



be 3 times the operating volume  with a minimum



recommended sizre of  400 gallons?  (Vt  = 3 x Vo).



      After sizing the operating volume,  the designer



should check to  ensure an  excessive  number of pump



starts per hour  will not occur.   This will happen



when the sewage  inflow to  the  tank is equal to half



the pump capacity.



      When designing the coJ lection  tank,  the sewage



pump suction lines should  be placed  at the lowest



point on the tank and as far away as possible from



the main line inlets.  The main  line inlet elbows



inside the tank  should be  turned at  an angle away



from the pump suction openings.
p.



u-                   it may be larger.
                          The recommended size of  the  reservoir tank for



                    most applications is 400 gallons.   In  special, cases,
              ......                         65
t_                   _.         ...        -    .

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                                SYSTEM PUMP-nriWN TTMF
r
                           After the  vacuum pump,  cr.oll ect.n.on  tank,  and

                     reservoir tank are sn.?:fd,  system pump-down. time for

                     an operating range of lh"" to ?Q" Hg  shouJ.d be

                     checked.   This calculation will show the amount. o1

                     time :it will take  the Reler:ted vacuum pumps to

                     evacuate (pump-down)  the collection  piping from lh'"

                     Hg to 20" Hg.   This formula is shown  below:
                     t --   (0.045 cfnjrmiQl l'^Z3._yE;_-i.yGt:-yol_i_yr t
                                    gal                Ovp cfm
(-
!1
L
                     where :t   = System  pump-down time (mn'.n)
                           Vp  = Volume  of collection system  piping (gal)
                           Vet - Volume  of collection tank  (gal)
                           Vo  = Operating volume of collection tank (gal)
                           Vrt = Volume  of reservoir" tank (gal)
                           Ovp = Vacuum  pump capacity (cfm)

                           In no oaese should "t" be greater  than  3 minuter

                     nor less than 1 minute.   -I-f greater than  3 minutes,

                     the size of the capacity--of the vacuum  pumps should
                                        . -:-.--
                     be  increased until -"-t~"  is less than 3 minutes.   Tf

                     "t" is less than- It minute,  the size of  the reservoir

                     tank should be increased.

-------
                                                        gns
 L
c
[
                          Vacuum pumps may be either  the  sliding-vane or


 f~ " '                the liquid-ring type  (See Chapter  TTI. C. 3  for  a
 I
                    discussion on the differences between types).   In


                    either case,  the pumps should be  aivcooled  and  have
 l._

                    an end (ultimate) vacuum of 29.3"  Hg  minimum at  sea
 r
 j                   level.   The pumps should be capable of contn nous


 .-                   operation.   Duplicate pumps, each  capable  of


                    delivering 10O%  of the required  air  flow  (cfm),

 (
 ;                   should be provided.


                          Lubrication should be provided  by an integral.


                    fully recirculating oil supply.    The  oil separation


 P                   system should also be integral.    The  entire  pump.


 ^                   motor,  and exhaust should he factory  assembled and


 f                   tested unit mounted on vibration  isolators and should

 L.
                    not require special mounting or foundation


 )                   considerations.
[7             .  .                           G7

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       Both  vertical and horizontal discharge pumps




are acceptable,  although the latter is recommended




due to lower  suction lasses than with vertical




pumps.  Duplicate  pumps,  each capable o'f del 3 vering




the design  capacity (gpm) at the specified TDH (ft)




should he used.




       Each  pump  should he equipped with an enclosed,




non-clog type, two port,  grey iron impeller,




statically  and dynamically balanced,  capable of




passing a 3"  sphere.   The impel").er should be keyed




and fastened  to  a  stress proof steel shaft by a




stainless steel  lockscrew or locknut.   Pumps should




have an inspection opening in the discharge easing.




       The pumps  should be fitted with double




mechanical  shaft seals.   A pressuri/rer mounted on




each pump and connected to the seal chamber is




required to maintain a pressurized supply of light




lubricating oil  in the seal chamber.




       Fach  pump  should be coupled to its driving




motor  by a  grey  iron bracket with machined rabbet




fits and a  flexible coupling.   Stainless steel shaft




sleeves are to be  supported by sealed ball  bearings




in a one piece grey iron  frame.   Eaolv pump should be




a base mounted unit with  a cast iron base.




      A certification  from the pump manufacturer that




the pumps are suitable for use in a" vacuum sewerage




installation is  required.




                        68

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r
I
i
I
L
[

[

r.
                          Equalizing  lines  are  to be installed on each

                    pump.  Their purposes is  to remove air from the pump

                    and equalize the  vacuum acrossed the impel!! er.   HI ear

                    PVH pipe is recommended for use  as small  air leaks

                    and blockages will he clearly visible to the system

                    operator.  On small discharge pumps (generally less

                    than 1.00 gpm),  the equalising lines should be fitted

                    with motorized full port  valves  which close when the
L.
                    pumps are in operation.
r    .
                                           69

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       Two  vacuum tanks are required for each station:

 the  collection  tank and the reservoir tank.   Basic

 construction  of the tanks is similar,  differing only

 in size, shape,  and type and location of the

 openings.   Roth steel  and fiberglass tanks are

 acceptable.

       Steel tanks should he of a welded construction

 and  fabricated  from not less than 1/4" thick steel

 plates.  The  tanks should be designed for a working

 pressure of 20"  Hg vacuum and tested to 28"  Hg

 vacuum-

       Each  tank is to  be furnished with the .required

 number and  si?:e  of openings,  manways.  and taps,  as

 shown  on the  plans.

       The tanks should he sand-blasted and painted at

 the  manufacturer* s location and painted as follows:
      Internally: One coat of  epoxy primer and two
                  coats of coal  tar epoxy.

      Externally: One coat of  epoxy primer and one
                  coat of epoxy  finish.
      Each tank should be supplied complete with

sight glass and its associated  valves-

      Fiberglass tanks may he substituted using the

same specifications.  Fiberglass  tanks are to have

150 psi rated flanges.
                       70

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 !                                       STANDBY  GENERATOR
 ^



 j                         The standby generator should be capable of

                    provlding 100% standby power for  the station
 i                                                                   -.
 i                   operation.  It typically is located inside the

 '.' ' '                station, although generators located outside the  ,

                    station in n enclosure are also  acceptable.
L
                          This item includes piping,  valves,  fittings?,

                    pipe supports, fixtures, drains,  and other work

                    involved in providing a complete  installation.

                          Station piping includes all piping within the

                    station,  connecting piping to the vacuum reservoir

                    tank,  collection tank,  vacuum sewer  lines,  and force

                    mains.
                         .....
                          Wastewater,  vacuum,  and drain  lines larger than

                    4" should be cast iron,  ANSI B16. 1.  125  psi for

                    exposed installations.   For buried Installation.

                    mechanical joint.  ANSI  A21. 11. AWWA  Clll.  cast iron

                    should be used.   Fittings should  be  flanged and

                    mechanical joint as appropriate (ANSI AS1. TO,  AWWA

                    C110).   One-eighth inch (1/8") thick red rubber

                    gaskets should be used on all flanges.   Vacuum lines

1^                   as well as other line*? under 4" should be Schedule 80

[" "                   PVC.   Building sanitary drains are to be PVU fJWV pipe
< _
                    and fittings.

                                           71

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r
       The piping should be adequately supported to




 prevent sagging and vibration.   It also should be




 installed in a manner to permit expansion, venting




 and drainage.




       Far fiberglass tanks,  all pipi.ng must be




 supported so that no weight is supported by the tank




 flanges.   Flange bo3.tr. should only be tightened to




 the manufacturer" s recommendations.   Provisions must




 be allowed for inaccurate opening alignment.




       All shut-off va3 ves fitted within the




 collection station should he identical, to those used




 in the collection system piping,  with the exception




 that they be flanged.




       Check valves fitted to the vacuum pi ping are to




 be of the 125 Ib.  bolted bonnet,  rubber flapper,




 horizontal' swing vari.ety.   Check valves are to be




 fitted with Buna-N soft seats.




       Check valves fitted to the sewage discharge




 piping are to be supplied with an external, lever and




 weight to ensure posits ve closing.   They also should




 be fitted with soft rubber seats.




       On  the. upstream  side of e^ch side of each




 vacuum ewer isolation  valve,  a vacuum gauge of not




 less  than 4-1/2" diameter should be installed.




 Gauges should  be positianed so that they are easily




 viewed when  the isolation valves are operated.




Diaphram  seals should not fcie used with compound




gauges.   Snutabers  are recommended for all compound




and pressure gauges.




                        72

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 r
                                     MQIQR-CQNIRQL.CENIER



 j                         The Motor Control Center (MCC) Is to be
 t
                    manufactured,  assembled,  wired, and tested by the

 I                   factory i.n accordance with the latest issue of NEMA

 I ' '                 Publication ISC2-322,  for Industrial Controls and

                    Systems.   The vertical section and the individual

 I                   units shall bear a UL label,  where applicable, as
 i
                    evidence of compliance with UL Standard 84H.

 I                         Wiring inside the MCC is to be NEMA Class IT.

 j                   Type  B.   Where Type 8 wiring is indicated, the

                    terminal blocks should be located in each section of

 j                   the MCC.
 i
                          The enclosure should be NFMA Type 12-Wifch-

I                   fiasketed Doors-   Vertical sections shall be

                    constructed with steel divider side sheet assemblies

*                   formed or otherwise fabricated to eliminate open

f                   framework between adjacent sections or fulllength
1.                                      -            -
                    bolted-on side sheet assemblies at ends of the MCC.
I
[
L
L
E
                          The  MCC should be assembled in such a manner

                   that  it  is not necessary to have rear accessibility

                   to remove  any internal devices or components.   AIT

                   future spaces and wireways are to he covered by blank-

                   doors.
                                           73 -

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 r
                            The discharge pumps  anri alarms are  controlled

                     by  seven (7)  probes insi.de the collection bank..

                     These probes  are 1/4" stainless stee.J with a PVl";

                     coating.   The seven positions are an foljOWP:

                            1.     Ground probe
                            2.     Both dn.wcharge pumps r.t.op
                            3.     Lead discharge pump start.
                            4.     Lag  discharge  pump start
                            5.     High l_eve".l alartn
                            G.     Reset frit-- prrihf? tt7
                            7.     High level nut-off:  stops a!11  discharge
                                  pumpp (auto position only) and vanuum
                                  pumps (auto and manual, position*?)
t

L.
f
       Figure 29  give??; apprnxi mate -elevations of

prohes in the collection tank  relative  to  the

discharge pumps  and incoming  vacuum mains.

       An acceptable alternative to the  seven probes:

ifj a  single capaci tanr:ei.ndur:ti ve type  pKTihe r:apat:i1

of monitoring !l.l.  Keven -set points.   Thif*  type of

prohe requi.res a transmi tteK/transdi^cer to r?end a 4

2O mA signal to  the MO!":..
                                              74

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 r
                                                          VACUUM COLLECTION TANK
      r INCOMING VACUUM
                                                    AT LEVEL OF BOTTOM
                                                    OF MET ELBOWS
                                                    ON VACUUM SEWERS
                  PROBE f7
ST MM FROM
BOTTOM OF
INLET TO TOP
OF DISCHARGE
PUMP VOLUTE
                                            15-2< ABOVE
      ABOVE
PROBE 5
                                            PROBE fcTO
                                                TIME OF
                        ABOVE
                     DISCHARGE PUMPI
                                          GROUND
                                          ABOVE TANK
-1
                                        FIHllRF  29
                                    TYPIT:AI  RLFVATTHNS
                                OF  I.EVFl.  nriNTROI. PRORES

                                               7S

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r
r
                    IELEPHQNE-QIALEB








       A voice communicationtype automatic telephone




 dialing alarm system should be mounted on a wall




 adjacent. to the MI'IC.   The system should he self-




 contained and capable of automatically monitoring tip




 ho  four Independent alarm conditions.




       The monitoring system sho.Tl,  upon the opening




 of  any one alarm point,  access the telephone 1ines.




 wait  for the dial tone,  and begin to dial the first




 of  four field programmed telephone numbers.   The




 system will then deliver a voice message indicating a




 two digit station number and the fault status at that




 station.   The message will be repeated a preset




 amount of times with sufficient space between




 messages to allow the called individual to




 acknowledge receipt of the call.   Acknowledgement of




 the message is accomplished by pressing a TOUHH TONF*




 key on the telephone between messages.   Fol lowing thr;




 acknowledgement,  the system will  vocalise a signoff




 and hang up.   The system then enters a 30 minute




 delay  to allow adequate time for follow-up measures




 to  be  taken.               -       -




       If,  during the delay,  another fault occurs,  the




 system will begin recalling.   Additionally,  the




 system can be called at any time,  from a standard




 telephone,  whereupon it will answer the call and




 deli.ver a  vocalised message indicating the station




number  arid fault status at the location.




            "           76

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 r
"t.


 r
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c
c
      If the delay elapses and  fault.?? still exist.



the system will begin dialing in  1  minute intevals
 !                   attempting to deliver the fault message.  If no


                    acknowledgement is received,  the system will hang up,


 I
 L                   wait  60  seconds,  and ca~l1 the next priority number.



 i                   After dialing the last priority number, the system

 I.
                    wil 1, j f rieoessary,  return to the f irst priori ty



                    number and repeat the sequence indefi nitely.



                          If the  monitoring sysem is to be hours^ri in th

 r

 [                   MCC,   provi.sions must be made to isolate the system



 r  .                 from  interference,     .      .


                          The monitoring system should be provided with



 j                   continously float charged batteries for 24 hours

 I

                    standby  operation in the event of a power outage.
P                           -              "77

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r
L
                                         VAGUUM..GAUGES



                          All vacuum gauges should he specified to have

                    stainless steel bourdon tube and socket  and to be

                    provided with 1/2" bottom outlets.  Polypropylene or

                    stainless steel ball valves should be used  as  gauge

                    cocks.

                          Vacuum gangers should be provided at the

                    following locations:
On the side of the vacuum  reservoir tank
in a position that is easily  viewed from
the entrance door.

On the collection tank  in  a position that
is easily viewed from the  stairway
leading to the basement.

On each incoming main line to the
col.lect.ion tank,  immediately  upstream of
the isolation valve on  the line.    These
gauges should be in a position  above the
incoming main lines that is easily
from the operating position of  the
isolation valves.
                          The connection from the i ncnming main lines to

                    the  vacuum gauges should b made of PVH or f:PVf:

                    pipe.   Copper pipe is not to be used for this

                    purpose.
                                           78

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r
                          The MCC should  contain  a  7-day circular chart


                    recorder with a minimum  chart diameter of 12 inches.


                    The recording range is to  be  OflO"  Hg vacuum,  w;i th


                    the 0 position at the center  of the chart.   The chart


                    recorder is to have stainless steel bel !l
                          The basement of the vacuum  station should be


]                    provided with a 15" x IS" x  1.2" deep sump to collect
i.
                    washdown water.   This sump will be  emptied by a
r~

'L                   vacuum valve that is connected by piping to the


r                   collection tank.  A check valve and eccentric plug


                    valve should be fitted between the  sump valve and th=?


f                   collection tank.
I 7               -           -                7SJ

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 L                               SECTION
              Construction of a vac:uum sewer system is similar to


         conventional systems.   Utilizing small, diameter pipes in shallow


 L        trenches and having the ability to avoid underground obstacles


 r~       virtually at will makes this type of construction attractive to


         contractors.   There are,  however,  certain inherent construction


         problems associated with vacuum sewers.
 L.

              It is imperative "that inspection be performed by those with
 i 

 {        a thorough knowledge of vacuum sewer technology. .   The desj gn of


         the system and its hydraulic limits must be understood.
                                 /

 L.
[


E


[
I                    Unforeseen,  underground obstacles are a reality i n


,            sewer  line  construction.   Water and. gas lines,  storm


L~            sewers,  and culverts at unanticipated locations all. may


f            present  difficulties during construction.   Natural
I                      . -.     ...     .       ....

             underground conditions,  such as rock,  water,  or sand also


             may present more problems than anticipated.  With the


             "straight line,  constant grade" nature of gravity sewer


L-            construction,  these obstacles usually result in field


j~            changes.


                    These field- changes may include installing an


             additional  manhole.'   It may also entail removing and


             relayi.ng part  of the pipe at a di f f erent grade.  Depending


             on the specifics,  the line change may also result in a


             grade  change which could affect the depth and grade of the


             entire gravity sewer system.   Another lift station may have

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I
             to be installed.  Alterations  at  the treatment plant may he




             required.  Unfortunately,  this scenerio is all too common.




             The end result is an increase  in  contract price through a




             change order.




                   One key advantage  of vacuum sewers is the flexibility




             they allow for line changes during construction.




             Unforeseen,  underground  obstacles usually can  be avoided




             simply by going under,  over or around them.  There may be




             cases where line changes will  be  necessary,  due to




             hydraulic limitations.    However,  the likelihood of this is




             greatly reduced with the flexibility vacuum sewers aD.lowZ




                   One must be very carefuD  not to make change for the




             sole sake of making construct!.on  easier.   F.very line change




             should be carefully evaluated  for  its effect on the




             performance of the overall  system.   Will the change




             increase the amount of lift in the system (and ultimately




             result in increased power costs)?   Will  the change result




             in an undesirable hydraulic condition  at a key location in




             the system?  How will the owner be affected?  Will the




             change put the pipeline  in a location  that the owner's




             equipment cannot reach?  Will  i t result  in operational




             problems in  the future?  All. of these concerns must be




             weighed against, the potential  construction cost savings




             prior to a change being  authorized.




                   Line changes are made through the  uso' of . f i tti.ngs.




             No 90-degree bends should be used  in  vertical  or horizontal




             line changes.   Concrete  thrust blocking  genera!! ly is not




             necessary, however,  compaction  in  this zone is vi tal.

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              2.
 !                   Like line changes, grade changes  should  not. be made


              without a thorough evaluation of how  that,  change  will
 i                                                                   *-.

 i             affect overall system performance.  The abili ty to make


 ,'  ' '          grade changes to avoid unforeseen, underground obstacles is


              a huge advantage; however,  the abuse  of this freedom can

 i
 1             result in major problems.  This very  issue has been the


              cause of conflicts between the contractor  and  the engineer

 r
 '.             in past projects.   J he engineer's inspector instinctively


 i             desires to eliminate lifts to improve the  system
 i

              hydraulics.   This results in a deeper installation.   The

 r '
 I             contractor,  on the other hand, is constantly wanting to add


              lifts to result in a shallower installation.   As  long as
 r~

 I             nei ther party loses sight of the system' s  hydraulic 1imits


 r--            and the effect on operational costs,  a  conflict does not


 1   .          have to take place.


 j                   Vacuum sewers must be laid with a slope  toward the


              vacuum station.   The only exception to  this is where


 (             vertical profile changes (lifts) are  made.  The pipe must


              slope toward the vacuum station between lifts.


                    A minimum of 0. 2% slope must be maintained  at all


 [             times.   To ensure this,  a laser typically  is required.   The

 L.

              use of automatic levels also is acceptable when an

 r

 j             experienced instrument man is on site.   In areas  where an


              obvious downhill slope exists, the pipeline follows the


 "-            contour of the ground-   Grade should  routinely be checked


j~             by the engineer" s inspector.
f
I                 -                            3
L..

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             3.
                   Most  contractors have a crew installsng main 1ines




             and a second crew  installing the services (vacuum valve




             pit).   It is common  for the line crew to install  wye




             fitting on  the main  to accept later piping from the pit




             crew.   Typically,  the  pit crew installs the pit and then




             must connect the pit to the main.   Connecting these two




             fixed points, which  have different elevations,  with rigid




             piping sometimes can be difficult.   Many times the result




             is the excessive use of fittings.   This situation can be




             avoided by  proper  planning and coordination between crews.
L
       Each service setting,  in- terms of depth, typical ly is




custom designed.   The relationship between the ground




elevation  where the pit will be situated and.the elevation




of the customers basement/building sewer dictates the depth




of service required.   In addition,  the length of connecting




lateral required must be considered to allow for sufficient




slope  on the  building sewer.   Prefabricated valve pits with




fixed  dimensions can sometimes make pit location critical.




Moving the pit  to a lower elevation,  while allowing




additional fall for the building sewer,  may result i.n lift




being  necessary to connect to the main (elevation of main




is generally  independent of  elevation of the pit).   Movi.ng




the pit to a  higher elevation may resul t i.n i.nsuf f i cient




fall available  for the building se,wer.   Each valve pit-




location should be evaluated for adequacy and vwri.fi>-d to




the contractor  prior shipment of the valve pits.




                               4                        -  .

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                              Substitutions
 j          '         Equipment sutamittals should be approved  by the

              engineer prior to the contractor ordering  the  sspraei fie

 I             equi.pment.   Virtually all of the components  in a vacuum

 |~~ '           system are available from more than one  manufacturer.   Even
'I
              though much research and development currently is taking

 j             place,  the vacuum sewer industry has grown and improved

              largely by the trial and error method.   For  this reason,
 r
 |_             substitutions of specified equipment are discouraged-   This

 r-            is not to say that new or alternative brands should

              automatically be ignored; it simply means  that care md

              judgement should he exercised prior to any major deviation.

                    Should a substitution be desired, .the  contractor

[             should submit the following information  to the engineer to

,--             allow for a complete evaluation of the situation:

'-               *  Identify the product by stating the manufacturer*
                   name and address,  trade name of product,  and the
[                  catalog or model number.

                *  Include product data such as shop drawings,  samples,
r                  etc.

                *  Give itemized comparison cif substitution  with
(                   specified equipment,  listing variations.

l~-    ,           *  Give quality and performance ^comparison of
                   substitution with specified equipment.

[_               *  Give cost data comparing substitution with specified
                   equipment.

                *  List availability of maintenance servicws an wr11 an
                   replacement parts.
L
*  Show the effect of substitution on the project
   schedule.

*  Show the effect of substitution on other related
   equipment.

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5.
      a.

            The engineer should be  present during the

      entire testing period.  This  holds  true for both the

      vacuum station test and the collection  system test.

      Any leak not discovered due to  flawed testing

      procedures,  either intentional  or unintentional,  will

      Quickly become evident once the system  is

      operational.  An operator can simply check the vacuum

      charts daily to see if any leaks are present.

            During testing,  temperature and/or climatic

      conditions may vary..   The following conditions may

      affect the vacuum readings in the pipe  being tested:

         *     A drop in temperature  may  occur.   The-; effect.
               will he cooling of the pipe and the air in
               it thus causing contraction of both.   The
               contracting of the air within  the pipe will
               cause an increase in vacuum (Figure 3O).

         *     Climatic conditions may cause  a change in
               the barometric pressure. -  Before  a rainfall
               the barometric pressure may drop  by
               approximately onehalf inch of mercury.   A
               vacuum gauge measures  the  di fference i n
               pressure br-'tween the volume being tested and
               the atmospheric pressure.   Therefore,  any
               change in barometric pressure  will  cause an
               equivalent change* in pressure  on  the gauge
               being used i n the vacuum test.


            Where climati c changes may occur  duri ng a

      vacuum test,  it is recommended  that pipe temperature

      and atmospheric pressure he recorded at the beginning

      and end of the test.

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-------
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           To  correct the test results,  first use Figure

    30 to  determine  the effect of any change in

    temperature  (T effect),.   Then apply the following

    formula:
I .
                        T ef feet- (API. -AP2 )-V2 = actual loss  in  line vacuum
                                             FXAMPLE
                                S1ART
Temperature of pipe  ( F )           96
Atmospheric Pressure (Tn. Hg)  AP1=HO. 0
Line Vacuum (In. Hg)           V11 =24. 0
                                                            "   65
                                                          AP2=29. 5
                                                           V2=23. 4
OHANGF
  30
 0,6
                          T effect from Figure 30 for a 3O F
                          drop in temperature is 24.3-in. Hg.
                   Vacuum Loss
                  = T effect  -  (API -  AP2)-V2

                  =     24.3  -  (30. 0-29. 5) -23. 4

                        24. 3  -  0. R - 23. 4

                  =      0. 4  in/ Hg
                                            a

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                          All vacuum piping, and connected appurtenances,


                    in the vacuum station should be tested for


                    tightness.   A final test of the station pi ping  should


                    be done.   In . this test,  the station piping is


                    subjected tn 24-inohes of Hg.   There should be  no


                    loss of vacuum in the 4--hour test period.


                          Al] of the controls should be tented at startup


                    to see that the system is functioning as designed.


                    This includes the vacuum pump controls, the sewage


                    pump controls,  and the telephone dialer.
                          Testing of the collection system is usually


                    carried out dai.ly prior to backfilling by plugging


1                    all connections and subjecting the system to  24-


.                    inches of Hg vacuum.   This daily testing usually  if


                    not a strict requirement,  rather it is recommended as


j                    a  means of quality control to the contractor.


                          The collection system also is subjected to  a


^                    final acceptance test.   The engineer should check to


|~                   see that all. di.visi on val vess are opened prior to  and


                    at the end of the test-   The system should be


r


                    vacuum of IX per hour over 4 hours is acceptable.


I-                   Line sections that were successfully tested on an


P                   individual basis during the daily testing, may fail
i

                    the final test when considered collecti.vely-

(7
                   subjected to 24-inohes of Hg vacuum.  'A drop  in
i                                                         t

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             6.
r<
                    The above sections provided  insight, into some of the

              inherent problems associated with  vacuum  sewer

              construction.   These problems can  be  avoided by sound

              design,  proper inspection, and preconstruction

              planning/coordination between the  engineer and the

              contractor.

                    Based on a 1989 study of six (6)  systems,  three

              problems appear to be prevalent during  construetlan.   They

              are discussed below:
                         Solvent welding PVG pi pie in temperatures
                   approaching or  exceedi ng -freezing. 1 ed to vacuum
                   leaks.  Some contractors made the mistake of
                   the glue warm,  only  to apply  it to a pipe that was
                   much colder.  This 3.ed to leaking joints, and
                   difficulty in passing the final leakage test.
L

[
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L_
                         Poor workmanship  by  the contractor led to valv
                   pit settlement.  This resulted in alignment problems
                   for the owner  at the time  of the valve installation
                   (vacuum line entering the  pit moved from its level
                   position).
                         Two .fixed pointR,  at  varying inverts and
                   varying locations, but requiring rigid connection
                   piping,  resulted  in the  excessive use' of fittings.
                   These fittings? many times were  located within the pit
                   excavation.  This i:iverexcavat.Fd 7one was one where
                   lack of compaction could easily lead to settlement-
                   Later settlement, in fact,  Ted  to fitting failures.
                                          1.0

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 I
 L.
 r
r
l
       The first problem can he avoided by not solvent;



welding  joints during -temperatures of 40 F and colder.



However,  since this may not practi oa]l for some contractors,



a better  solution  would be to minimize the number of

                                                      **.


solvent welded joints in the system.   Along these  lines,



there  has been a significant move in the vacuum industry



toward gasketed pipe and fittings.



       Valve pit settlement problems can be avoi ded by



better quality control on both the contractor* s and



inspector's part during construction.   Taking time to



assure proper  alignment and proper compaction around the




pit will  greatly reduce the likelihood of this problem



occurring.  Design improvements,  specifically t.he t.apered



pit,  have a]lowed  contractors to improve their compaction




effort.



       The use  of fittings in the servi.ce lines can be



minimised by proper planning and coordination between  line



and pit crews.   To mini mi re the di.fficulti.es,  some




contractors install the valve' pi ts first.   The use of




gasketed  fittings,  which adds a certain degree of



flexibility, will  also alleviate some of these problems.
r

                                           11

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      , i "i  ,L.;.^.     ,F,: OPERATION AND MAINTENANCE COHSJOERATJONS.;^^";"V:e-',/'-
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                 0 P E R. A.T 10 N   AND  ..M A I N T E N A -W C -E
              1.
                & Mg3:ntenance_Manual
      To operate a vacuum sewer system requires proper

training.  Operation and Maintenance Manuals'(O&M Manuals)

are a vital part of this training process.  Problems arose

in some of the early vacuum systems due to the .lack of such

aids.   Manufacturers and engineers are now recognizing this
                  \
fact and are reacting accordingly with improved technical

assistance and O&M Manuals.

      A well written O&M Manual should contain the

information necessary to achieve the following goals;
                          To provide an accessible reference for the
                          Mastewater collection system-operators_in ..v  .
                          developing standard operating and maintenance
                          procedures and schedules.    .   .   

                          To provide a readily available source of data,
                          including permits,  design data,  and equipment
                          shop drawings which are pertinent to the
                          particular system.-   ......          "

                          To provide the system operators assistance and
                          guidance in analyzing and predicting the system
                          efficiency.

                          To provide the system operators assistance and
                          guidance in troubleshooting the system.    .

i

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[.
r
      While -an Q&M Manual is a valuable tool, it should not

be viewed as the source of the ultimate solution to every

problem.   The degree of efficiency of the system depends on

the initiative,  ingenuity,  and sense of responsibility of

the system operator.   Also,  the manual, should be constantly

updated to reflect actual operational experience, equipment

data,  problems,  and implemented solutions.
                   \.
      The O&M Manual should contain the following

information as a minimum:
                         All  design  data  should  be given.   Included
                  would  be information relating to the system make-up.
                  such as the  number  of  valves,  line footage and line
                  sizes.  Also included  would be component sizing
                  information,  anticipated  operating ranges,  and other
                  important  design  considerations.   As-built drawings
                  showing all  system  components should be included.
                                             MANUALS
                         Installation and maintenance  manuals  from  the
                  manufacturers of the major equipment  should be..  .
                  included.  A list showing the manufacturer  and
                  supplier as well as contact persons,  addresses,  and
                  phone  numbers should be compiled.
                               _WARRA.N.!y. INFORMATION

                        All warranties, including effective  dates,
                  should be listed.                           *   -
                                   _HQP QB6WIN.es

                        A list of all approval drawings  should be  made
                  which identifies the manufacturer, model  number,  and
                  a general description of .the equipment.   A copy  of
                  each approval drawing should be  included  with the O&M
                  Manual.

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r
                         All applicable permit.s. such as the National
                   Pollution Discharge Elimination System (NPOES)
                   permit,  should be included in the manual.  Mater.
                   Quality standards should also be included.
                          -OPERATION A.NQ QQNIRQL INFQRMAHQN
r ~            
j
j                         This section should include a description of
                   the overall system.   The major components should be
r~                  identified.   The following information should be
I                   given for each major component:
i.

ir   -                      *     Relationship to adjacent units
!                         *     Operation
                         *     Controls
f                         *     Problems and -troubleshooting guides
                         *     Maintenance
                         *     Preventative maintenance schedule
                         *     Equipment data sheet
[                                -EERSQNNEL INEQRM.A.HQN.

r                        A description of the manpower requirements,
1                   including qualifications and responsibilities should
                   be listed.
                                       _REQQRDS

                         A list of the type of records, as well as a
                   list of reference materials that are important.
                   should be included.
                                           MAINTENANCE.
                         All equipment should be listed and nross-
                  referenced to equipment catalogs.   Maintenance
                  schedules should be established.  

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                                   -  .      -                      >    - -  *      -

                      _E[iEBiEfc!CY ''QEEBAIIfcls' AND RESPONSE 8088^1^''"5^

                         This section  should include a description of
                   actions and responses to be, followed during emergency
                   situations.  Included should be a list of contact
                   persons, including  addresses and phone numbers^ for
                   those responsible for various community services
 .
                                  _SAEE1Y lyFORfaAHQN

                         A safety plan  should be developed which
                   includes practices,  precautions,  and reference
                   materials.
                                          IY LISTING

                         A list of all  utilities in the system area
                   should be given, .including contact persons.
                   addresses, and phone numbers.
                          ,<.-- ..-,.*
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                          Information gathered from operating systems

 ,_. . .                suggests  that the effort to operate and maintain

                    vacuum systems has been overstated in past

 i"                   publications.   The generalization of vacuum systems

                    as being  mechanized,  and therefore,  Q&M intensive,
 f *
 I                   along  with  the conservative nature some engineers in

                   'recommending  staffing requirements,  many .times

 L                   resulted  in an overstaffing situation.

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                   b.
L

*
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      The system operator is responsible far the

following activities:
 ^
[
                   *

                   *
      Analyzes and evaluates operation and
      maintenance functions and initiates new
      procedures to insure continued system
      efficiency.

      Reviews and coordinates all data and records
      for the preparation of reports and purchase
      requests.

      Recommends all major equipment purchases and
      system improvements.

      Maintains effective communication with other
      employees,  municipal and government officials,
      and the general public.

      Has a working knowledge of all .phases of
      wastewater collection systems and has a
      mechanical background.

      Supervises daily operation and maintenance of
      the system.

      Inspects the system daily to determine the
      efficiency of operation,  cleanliness,  and
      maintenance requirements.

      Prepares work schedules.

      Prepares operational, reports and maintenance
      reports.            '

      Determines remedial action necessary during
      emergencies.

      Maintains communication with higher management.

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                      -  Fi ^~ -, "." ** rr -r.-^-_.-- '*^^^yt^f4^'^^^ri'CTFt^Jgyii'^jr'* v^M- '"*T5 , y^-*'*^;'-^""^*-^-  * .* "" ^vir
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I
 r                ...-..,  ......
 L.                                ...
                    It is desirable for the operating entity  to hire the

 ,             system operator while the system is under construction.

 f . -           This allows the operator  to become familiar with the

 1     '       system,  including the locations of all lines, valve pits.

              division valves, and  other key components.

                    To add further  training.  AIRVAC offers a  twoweek
 r
              training program at their facility in Indiana.   A general
 L.
              knowledge of vacuum sewers is obtained by viewing the .

              testing setup at this facility.   This setup includes clear

 f             PVC pipe with various lift arrangements where one can watch
 i
              the flow inside the pipe  during a wide variety  of vacuum

 1             conditions.   Faults are simulated so that that  the trainee

              can gain troubleshooting  experience.   The operator is

 [             taught the valve operation and its overhaul.  Finally.

              vacuum station maintenance is taught.

                    The best training is gained by actual operating

 f             experience.   Many times,  however,  the knowledge gained is

              done so at -the expense of costly mistakes.  This is

              especially true at startup time.   During this time the

 P             engineer,  who.provided day to day inspection services

 *-             during construction,  is gradually spending less time on the

 [~~             system.   The operator is  busy setting vacuum, valves and

              inspecting customer hookups.   Complicating the  situation is

              the fact that the operating characteristics of  the system

-------
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              confcinualH.y change until all of the customers are connected


              and  all of the valves finetuned.   However, with the


              operator being preoccupied with other tasks, this


              finetuning sometimes is not done;  problems develop;  and


              system  credibility is lost.  This  "training gap",  is


              present at the startup of virtually every vacuum system.


              This is an area of the technology  that needs improvement.


              One  solution is for the engineer to budget a 3 to 6  month


              on site training service to aid the system operator  in the


              finetuning and troubleshooting  of  the early problems.  The


              operator will benefit from the  engineer* s systematic


              approach to problem solving.  This  most likely will  instill


              a certain degree of confidence  in  the operator concerning


              the  system.   Operator attitude  is  vital to the efficient


              operation of a vacuum system.

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               ;,^.{^.;^|JS:^^                                      ,.ri.:.l. .  :--_.'.
              4.
^ !*,.*.-. 'iVfXi*8 >*' I'*'-.- "* =-" .".J-**.   -" -.--,-  f -.*-> j!'-1'^'*.*:/;, ;-.- ''  - -; *,**;?: -'. *>*.?
"; * *      -  '   .-,"'   - . " * " " .'*;- T,--ii ^'*fc-M;jj5L-iH---  -J;,'"-'..-   ; .-,>?!--  - "''.
sOc Bficfes XQ^SQ&SCX*^X* ^"r^:;1^^^>^''V^^v***" '" *."  .':? ": '"u *V:ri-"
                    For optimum operating efficiency,  it is necessary

              that a sufficient inventory of spare  parts be kept.   Some

              of the spare parts,  such as fittings  and pipe, can  be

              purchased through local  builder~s supply companies.

              However,  there are parts that are unique to vacuum  systems

              that can  not be purchased locally.  Typically, these spare

              parts are included as part of the construction contract.

              Following is a recommended list of spare parts that should

              be supplied to the owner during .the construction phase.
I?
L,
                                          TABLE IS
                                     SPARE PARTS LIST
     2 ea.
     4 ea.
     2 ea.
     2 ea.
     5 ea.
     4 ea.
     2 ea.
     2 ea.
     1 ea.
     1 ea.
     2 ea.
     5 ft.
    10 ft.  .
                                           Vacuum valves
                                           Cantr-allere/seneors
                                           Sensor/cleanout tubes
                                           Controller /sensor rebuilding kit
                                           Valve cycle  counters
                                           Three-inch "no hub" couplings
                                           Valve pits
                                           Valve pit bottom plates
                                           Standard collection sump
                                           Deep collection sump
                                           Valve pit covers
                                           Clear valve  tubing: 3/8-inch
                                           Breather, tubing: 5/8- inch

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 r

r
                    In addition to these  spare  parts,  there are certain

              specialty maintenance tools and equipment that are needed.
                                        TABLE IB
                              SPECIALTY TOOLS AND EQUIPMENT
  1
  2
100
  3
  2
  2
  1
 15
  2
  2
  1
  1
  1
  ea.
  ea.
  ea.
  ea.
  ea.
  ft.
  ea.
  ea.
  ea.
  ea. -
  ea
                                         Portable vacuum  pump
                                         Portable vacuum  chart recorders
                                         Vacuum charts
                                         Chart pens
                                         0-20" W. G. magnehelic gauges
                                         0-50" W. G. magnehelic gauges
                                         12 VOLT OC submersible pump
                                         Pump discharge hose
                                         Nohub torque wrenches
                                         Vacuum gauges
                                         Flexible mercury manometer
                                         Controller test  box
                                         Pipe locator
                    The vacuum station also requires spare  parts.   These
                                                         _. ," r:.-A.!!ir5fe..
             range  from spare pump seals to fuses.  Specialty  items that

             should be considered are:
                                        TABLE 1.7
                                   SPECIALTY EQUIPMENT
                                   FQR_yACIJL)M_SIAIJQN
D
E
r.
X a.
1 ea.-
1 ea.
2 ea.
2 ea.
1 ea.
                 Inductance -prob*     .  .  ... .
                 Probe transmitter
                 Prnbe microprocessor card
                 Vacuum swi tch    ..
                 Vacuum gauge
                 Auto dialer microprocessor card
                   10

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 when "i nt"i I trahi i in ami  iri1*'low was ririt  occur i (}.  wil.h 1.1 >*




 Karnt-.' none l.urji on.    It, is afe t;n  assume the  ?-;anie




 correlation  wxipst.fi;  with va<:uur sewer  KyKternr:..




         At thi :.;  Li me,  thousands of flow tneawuremwnts  have




 been made  on  pr esr-jure  sewer  f-iys twine:: w:i hh  a  w t rJc?
                  l.t-'d  1"inddngr-s  of  the earil.n er"  si.uii w:-; ;  hh.ii.




 f.!iwK l.yp'i r: I .'I y r'inge  fn>m 40 l.n BO <3pnd,  w i l.h  I i tt. I !-*




 wi->c-?k^l y  rir  ;-;< i'-rraon.!il  va (-! at. j.on,




         I'l'ip  avfl i 1 .-I|MT I :.i t".y  and pual i.hy  crl  wal'.er  .:i t t'V-ntf-;




 wa tisr use  <=ind  r:onst"rc|uanfr,.'J.y soweK 1 Lows,  ass d'ti-->!3  wt.^*i-'




 pK'rtKKu*'!?,   r:c'iininun i ty  af:1'1 uen< :^,  nature  nf  nr:r:up"mcy.  anci




 at'l'.'i t.udws  nf  upserr:  rw!-iat--d:.i n;:?  water  conrs^rvati nn.




 B=fi':'iuse  of" thp-jse  vari.ab.l P?:> and i.o proyn de a  r-,a1'elr,y




 factor,  tl'ip- flow  ratr-  norrna 1 "l.y af^fsum^-d 1:nr dfjKi.jgn  If; !>0




 tn '*'O gpod.




        Whll.t=f va':iiijm swers  arft snmet:;i meK thought  to  hf




 frt^w  of  inf 'i 1 trt-il..i on  and inflow,  TAT  can  ocrrrur -i.ri thf-




 non- vacuum porti.oris  of ' t.hr-> syKtetn,   e.g..   th> bu"ildi.ng)




 sewer.    In  some casefs  IX I  hap. been  extreme,   rfuw  l.o




 .leaking  hui.l dd ng  Fsewers  or house roof  drain0, bvi.ng




 oonner:hed  to th*  building  SRwer.   It  .is. prudent  to  makf->




 an allowance for  I&l  whien  adopting  a  deRi SJn  1" Low,  bar.r?d




 on the extent  of  T4.T  control   given  to  the projot'-.t,.




        An for daily variations in flows,  pwri orlr.  of  po.il.-




 moment flow which  may exceed  design  v<1 I ue:~ mriy occur '*




 OK 'A  timer;  per  day.    However,   these  are of 1 ittlr-




importance  due  to  their  r:hort time of  dur.'it.-ion>    There




are a I. so peri.ods  if ?ero 1" I riw.

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                             PFAK Fl. t'IW:"i
        Besides average  daily flow  rates and the'IK




 variabi liti es,  it.  it-;  important ti i cortsi der other




 f actors,  such at?  the rate  of'  'Mow from the individual.




 home  tri  the vacuum valve pit..   T h:i K i'lnw  r ai.ft  r:ari 'he?




 ciu i V,e hiij^h til. t.i tn<>>.




        Th*=- AmeK:ic:an So<.:let.y < if I..! i v i I  Fnginr-er:;  (ASIT)




 repofV-ed  pf'-ak fjjiws l-h;:it. may  or:r:uK" about,  t-.wi r:i-- per  yr-.=iK




 a?5 being  2t"i g;=il'tnris in  a 4 ininut.r,' per'i od,  nr "I OH




 3-'i'J horiK j.n nne hnur.    I hi-^y ci< > on  t.o de.scr-j be t




 simu!Lt.inaus  dlr-:< .-hargp'  frnrn .=i  hHUhtub  and r:




 washer resulting  in a 46 ci.iLlrin discharge nver a twn




 rni.nul.e period,  .ind havd rig  a high  prnhabi lit.y n1"




 rmcuranne.




        Bennett reported  starve  l"'l owr; of  BO  :jal.lonF5 in a  7




 minute period.   .loners reported findings f?i.mi "I ar t-o




 those of  ASCF nnd  Bennett  and  appl led  the d;=ita tn




 rK-gi-es&J.on aria l.yses.   The  results  of the  various




 studies are shown  in the Prossure  Sewer ?r:tlon of  t-.hia




manu'al  ( Figure A--A,  page ^~




        ATRVAl":  3"  vaTves  havn .=*  maximum  capacity of :"IO




gpm  when  connected t;o a  6"  or  "J arger main..   This




assumes that  the vacuum  ner:r>ssary  (B in.   Hy) to




the  va.lve  is  present at  that  part:i<':ular 'l.oc:r<1.e.    ! o




acheive this  capacity,   with the normal 111  ga'l Ion valve

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 r-
c
              5.     ftsrBuilfe -Qcatticias
                    It. is common in the industry for changes to be made

 ("""


 [             during construction.   The changes should be reflected on



 f-            the as built drawings.   As the name implies, these drawings
 i


 '             depict, exactly how the system was built.  This is a vital.



 f             tool tri the operating entity for maintenance.
 ;
 I 

              troubleshooting,  and future improvements or extensions to



 J             the system.



 r..                  An index map showing the entire system should be



              included in the as-built drawings.   Shown on this map will



              be all key components,  line sizes,  line identifications,


 I.
              valve pit numbering and locations,  and division valve

 f

 I             locations.   Detailed plan sheets of each line of the



              collection system should be included,  with dimensions



              necessary to allow the operator to locate the line as well



              as all related appurtenances.



                    Unique to a vacuum system is the need for an as-hui] t



              hydraulic map.   This is similar to an index map but also



              includes special hydraulic information:



                    *     the locations of every lift



                    *     the amount of vacuum loss at key locations,

                          such as the end of a line or the intersection

                          of a main and branch line.
                          number of main branches,  number -.of valves in

                          each branch,  and total footage (or volume ) of

                          pipe in each branch-
                   This  simple,  but vital information al 1 owr; t.he



             operator to make  intelligent decisions when finetuning or
             troubleshooting  the system.



E                                          12

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                            ,
      Another tpbX^, that.; is  helpfulL.to the .operator, is an .as-

built drawing of each  valve pit setting.   This drawing will

show the location of the  setting relative to some permanent


markers (house, power  pole. etc. ),  the orientation of the

gravity stub-outs, the depth  of the stub-outs,  and any

other pertinent site specific information.'  These records


are used by the operator  as new customers connect to the


system.

      The" vacuum station  drawings should be altered to

reflect changes made during construction.   Especially

important in these drawings are? dimensions,  since any

future modification will  depend on available space.

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 L        -    6.     Maintenance t^';: ^;?v'"^%J%^?|^^>%.:,,::;--; c/   . _.   /'.- ^
                                 **.- .*.; ,-J "*.-  *" '  .-. -.  *> __  operation


                    of  both the vacuum station  and the  collection

 f
I                   system.   The operator is  notified of low vacuum,  high


                    levels of sewage in the collection  tank,  and power

r  -
I. ,                   outages.


r                         Normal operation includes visiting each vacuum


                    station daily.   Some maintenance  procedures include


                    the daily recording of pump running hours and a

+                                             .    .
 ^^                 checking of all oil levels.    Once an operator is


L                   familiar with the operating characteristj.es of his


r                   system,  a simple visual check of  the gauges and the


                    charts in the station will  alert him of any


j                    problems.   This visual check  along  with recording


                    operating data generally  takes about 3O minutes.


[                   Weekly procedures include checking  battery terminals


r-                   and battery conditions of the standby generator,


                    cleaning of the collection  tank sight glass,  a check


I                    of  th= mechanical seal pressurizers of  sewage


                    discharge pumps,  and a test of the  telephone alarm


                    system.
c
r

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  /;-..' On ' .normal day.  the  operator, will not be




required to visit the  collection system.   Normal




station gauge and chart readings are an indication




that the collection system  is "Pine.   Depending on a




system" s history of breakdown maintenance,  some




periodic inspection may be  required.   This would




include the inspection  and  manual operation of each




valve on some regular  interval.   The breather lines




should b? inspected for the accumulation of




moisture.   An experienced operator will quickly learn




the sounds of a properly functioning valve.

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L
                    areas.

r
                    fcj.
                          Wastewater  co] lection systems: operate and must-




                    be maintained  365 days a year.   Variations in flow




                    and maintenance workload occur,  making it imperative?




                    that preventive maintenance he planned and




                    scheduled.  This  will  ensure that there is no idle




                    time during nnn peak workload periods.   Inspection




                    and maintenance planning and scheduling involves




                    time,  personnel,  equipment,  costs,  work orders,  and




                    pri orities.



                          A preventive maintenance schedule for all major




                    equipment should  he developed.   To initiate the



                    preventive maintenance tasks,  a work- order aypitwm




                    must be established.   This system identifies the




                    required work, priori. ty of task,  and any special




                    information,  such as the tools or parts required for




                    the job.    These  work  orders provide a record of work




                    completed.




                          Scheduled maintenance on the collection pT_pi ng




                    should be minimal.   Areas where difficult or unusual
                                "                '*.


                    conditions were encountered during construction




                    should be visited periodical! y.   flther areas to he




                    visited include steep  slopes and  potential slip

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       At. least once a year,  the division valves   ;.." ...




 should he checked.   This is done by moving the valve




 through the entire opening and closing cycle* at least




 once.   This procedure will keep va3.ves in operating




 condition.   In addition,  it will, familiarise the




 operating personnel  with the location of all valves.




       All vacuum valves should be inspected once a




 year.   They should be manually cycled to see that




 they are operating properly.   The controller timing




 cycle  should be recorded and compared to the original




 setting.   If necessary,  the timing should be reset.




 This entire procedure can be done by one man,




 requiring about 1015- minutes per valve.




       Every five or six years,  the vacuum valves




 should be removed,  a spare put in its place,  and the




 old valve returned to the workshop.   The valve should




 be taken  apart and inspected for wear.   If needed,




 the seat, should be replaced.   When the valve is




 reassembled,  a new shaft seal and bearing should be




 fitted.   The seals and diaphragms of the




 controller/sensor should be checked and replaced if




 necessary.   This procedure can be done by one* man,




requiring 2O30 minutes per valve.




       Preventive maintenance for the major equipment




at the  vacuum  station should be done in accordance




with manufacturers'  recommendations.   Yearly




maintenance  might include inspection of check valves,




plug valves,  vacuum  pumps,  sewage pumps,  generator,




and the telephone dialer.

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                          Although very little effort is required on a



                    day to day basis,  there will be times that emergency



                    maintenance is necessary.   This effort usually



                    requires more than one person,  particularly when i.t



                    involves searching for a.malfunctioning valve.   Many



                    times problems develop after normal working hours,



                    requiring men to be called out on an overtime basis.



                    Emergency or breakdown maintenance can occur in the



                    piping system,  at the vacuum station,  or at the



                    vacuum valve.



                          Assuming proper design and construction,  there



                    is  very little that can go wrong in the piping



                    system.   Occasionally,  a line break will occur,  due



                    to  excavation for other utilities or landslides,



 f                   causing a loss of system vacuum.   Using the division



                    valves,  the operator can easily Isolate the defective



                    section.



                         "Malfunctions at the vacuum station are



 i                   generally caused by pump,  motor,  or electri ca3



 r;                   control breakdowns.   Duplicity of most component**



 ~                   allows  for the continued operation of the system when



 i                   this  occurs.                          -.
r
iJ

-------
       Most emergency maintenance is related to ;;v~j^,.




 malfunctioning vacuum valves,  caused by either low




 system vacuum or extraneous water.   Failure of the




 valve is possible in either the closed or open




 position.   A valve failing in the closed position




 will  give the same symptoms as a blocked gravi ty




 line,  that is,  the customer will experience problems




 with  toilet flushing.   A phone call from the effected




 party makes identification of this problem academic.




 Fortunately,  this rarely happens.   Virtually all




 valve failures occur in the open position.   When this




 happens,  a loss of system vacuum occurs as the system




 is open  to atmosphere.   The fault monitoring system




 will  recognise this low vacuum condition and alert




 the operator of the problem.   A common cause of




 failure  in this position is the entrance of




 extraneous water into the controller.




       Valve failures,  if not located and corrected in




 a reasonable amount of time,  may cause failures in




 other  parts of the system.   A valve that is hung open




or that  continuously cycles will cause system vacuum




 to drop.   If the vacuum pumps oan not keep up with




this vacuum loss,  the result is insufficient vacuum




 to open  othr valves.   This,  in turn, -.may lead to




backups.   When  vacuum is "finally restored,  a large




amount of  sewage,  in relation to the amount of air,




will, be  introduced into the? system -possi b I y resulting

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 r
 L
r
L
r
                    in  "waterlogging";:.  "  When this occurs,  the system -;


                    must be manually operated,  allowing the vacuum pump


                    to  run  longer than  usual.   Repetitively cycling the


                    vacuum  and sewage pumps in effect 3 ncreases the


                    capacity of the vacuum station.   This repetitive


                    cycling is continued until the system "catches up".


                    At  that point the system is returned to its automatic


                    mode.
                                           'A

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7.
            Good records are important for the efficient.

      orderly operation of the system.  Pertinent, and

      complete records provide a necessary aid to control

      procedures as they are used as a 'basis of the system

      operation.   The very first step of any

      troubleshooting procedure is an analysis of the

      records.   This is especially true of the collection

      system.   A wealth of information its contained in the

      basic records kept on a daily basis.

            The following types of records should be kept:
            *     Normal maintenance records
            *     Preventive maintenance records
            *     Emergency maintenance? records
            *     Operating costs records
            *     Personnel record
            These records should be carefully preserved

      filed where they are readily available to operating

      personnel.   A31 records should be neat and accurate

      and  made at the time the data is obtained.

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                          The following records should be kept, on a daily

                    basis:
                          *      Date
                          *      Personnel cm  duty
                          *      Weather conditions
                          *      Routine duties performed
                          *      Operating range of vacuum pumps
                          *      Run  times of  vacuum pumps
                          *      Run  times of  sewage discharge pumps
                          *      Run  time of standby generator
                          *      Flow data
                          *      Complaints receri ved and the remedy
                          *      Facilities visitors
                          *      Accidents or  injuries
                          *      Unusual conditions
                          *      Alterations to the system
                          In addition  to this  daily information,  an

                   annual report should be  prepared to summarise the

                   operational characteristics  of the system.
L
r
L ^
                                          "22

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      Adequate records provide  information  which  tel 1

operational personnel when  service  was  last performed

and indicate approaching service  requirements.

Necessary scheduling of maintenance can then be made

without overlooking important aspects of system

operation.

      Results of periodic inspections should be

kept.   This would include a list  of all problems, the

cause of the problem, the repairs,  and

recommendations for future  improvements.
      Records should be kept concerning all emergency

maintenance.   This includes the following:
      *     Date and time of occurrence
      *     Person(R) responding to problem
      *     Description of problem
      *     Remedy of problem
      *     Parts and equdpment used
      *     Total time to correct problem
      *    .Recommendations for future improvements

-------
                                    QPBATING_CGSI__RECQRnS



                          To insure budget,  adequacy.  It- i s very important

                    to keep accurate information concerning the casts of

                    all operation and maintenance items.   Costs include:
                          *     Wages and  fringe benefits
                          *     Power and  fuel  consumption
                          *     Utility  charges
                          *     Equipment  purchases
                          *     Repair and replacement expenses
                          *     Chemicals
                          *     Misoel laneous costs
I                                    PERSONNEL  RECORDS
*                                   ..*. _.   ...-. .
u
|_                   Personnel records; should be  kept on all  empl

r-            Each  file should include information  about employment
i
1             application,  change of status, absences,  vacation time,  and

j             an  evaluation of performance by the immediate  supervisor.
t..

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 I.
              8.
                    A procedure for locating the source of a vacuum

              failure has been developed by AIRVAC as follows:
r
L.
                          When a low vacuum condition occurs in the
                          system,  isolate each incoming line tn the
                          collection tank to identify the problem line.

                          Close off the problem line.   Open the remaining
                          lines to clear the sewage from them.

                          Allow vacuum in.the operational lines to reach
                          the maximum vacuum level possible; then close
                          these lines off.                   --.   -

                          Open the line with the problem.

                          Starting at the collection tank,  go to the
                          first division valve on the problem line.
                          Connect a vacuum sage to a nearby vacuum valve
                          (or to a gauge tap.  if one exists) downstream
                          of  the division valve.   Close the division
                          valve and'observe' if vacuum builds" up.  "'If it -
                          does not,  the problem is between the vacuum,  .
                          station and the division valve.   If vacuum
                          rises,  repeat the process on the next division
                          valve.   Before reopening each division valve.
                          allow vacuum to build up in the non-problem
                          sections of the sewer to clear that section* s
                          sewage.  ';         .          

                          After isolating the problem section,  check each
                          valve pit to locate the malfunction.   Often
                          this can be accomplished by driving to each pit
                          and listening for the sound of rushing air in
                          the auxiliary vent.

                          After locating the malfunctioning valve,  follow
                          the manufacturer* s valve troubleshooting -
                          procedures.
                                                         
                          If  no valves are malfunctioning,  check for
                          underground construction that could have caused
                          a break in the transport piping.   Also,  walk
                          the route of the problem sewer and look for
                          evidence of a break,  such as a sunken area.
L..
                                           25

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             r.  ... . ,  .The. above procedure  is  a systematic approach to
         !  "-'.. .'-' ' "  -."l".  "-.  . ..I       '. *       ."<.",.*.'-... ,' ' '..'', .-*.
  " '     -'..  ,-.,iV:.' -.,;.: '..'. -  ., . - >    -  _ "'": . .-  -:.'.-' '?-;:<'. '          .". "'"

 ^^          locating the source of vacuum loss.   Sometimes a shortcut


 I..            can be  taken.   In a recent study of operating systems,  it


 r            was found that many times  the same valve(s) fail.   This is


              usually due to some particular hydraulic condi tion at that
 *
 r~  "
 !             specific locale.   In these systems,  the operators check


              these valves before any other isolation is done.   In

 r
 |             another situation,  a skilled  operator can usually tell  how


 c            far from the vacuum station the' problem is simply by

 I

 1             analyzing the vacuum charts.   This allows for the


 [   .          simplification of the isolating procedure.


                    There have been attempts made to determine the  time

 c~

 I             necessary to locate a failed  valve.   At AIRVAC* s



             ' Plainville.  Ind.  location,   a  valve was caused to fail at a


              location  unknown to the maintenance personnel.   This  valve
           .... ..?. -;  ..;  ':_;,., ,*!: -..-;. .*;? --.-  . L '-- -  -:  ..;-?tt?t>1f:tiHA>.*4l/tH(&*t\*i:^'-\,'-'  .-v-.-;  -.  ;:;. -

              was located and the problem corrected in 21 minutes.


              System operators report that  the typical valve failure  is


              located within  30 to 45 minutes.   Most also cite driving


              time from their house to the  system as being the critical


              factor in this  response time.    A key component in  continual


              operation is an effective alarm system,  coupled  with



              available maintenance personnel.
[

r

-------
9.
"' 2f
Qa Systems"'
      a.

            Early vacuum systems were often plagued with




      consistent operational problems.   These systems were




      installed without sufficient field testing of system




      components.   In addition,  operation and maintenance




      guidelines were not yet available.   As a Vesult,




      several operational problems were encountered.  '



            Early systems,  particularly those by VacQ-Tec.




      experienced problems because of the lack of knowledge




      of the two-phase transport' concept.   Small vacuum




      mains,  improperly planned vacuum main profiles, too




      large liquid slug volumes,  and insufficient air all




      resulted in transport problems.        - <  . 




            Vac-Q-Tec* s systems also located sensitive




      electronic valve control equipment in 55 gallon drums




      near to the sewage holding tanks.   Corrosion of these




      drums and the control, boxes caused numerous




      problems.   The complex electronic control system




      proved to be a major drawback as highly skilled




      technicians were required to operate the system.




      Valves on Vac-Q-Tec systems are presently being




      retrofitted with AIRVAC valves.

-------
                     .     Early. Colt "and AIRVAC systems lacked components '&*.

                    that  are now generally accepted as minimum design

                    standards.   The lack of standby power and fault

 j                   monitoring devices are examples.   The lack of standby

                    power 3 ndirectly caused the Colt valve boot to

 !                   rupture.   During power outages,  liquid"built up

                    behind these valves.   When power was restored and the
 i
                    valves cycled,  the higher than normal column of water

 I                   resulted in the timed valve operation sequence
 i                                       -
                    closing on the  column of water instead of on air. " '
 r                             '                       .             _'".:
 L                   This  "water hammer" of sorts resulted in unusually

 ',"                   high  forces which ruptured the valve boots.   These

                    problems were alleviated to a large degree when
 r *
                    standby power was added to the system.   .

 ^^                  .-....- AIRVAC* s jearly valve pi-ts were made of a tar-  -"><-
 i                     -.-..;".           '
                    impregnated paper which deformed when placed in

 r                   unstable soil or in areas subjected to vehicle
 i             .                 .  . .              _
                    traffic.   This  deformation eventually led to damaged

 I                   valves.   Additional problems resulted from the use of
 t.
                    valve  pits without bottoms in areas of high

j                   groundwater.  Tn this case,  water entered the

r                   sensitive  sensor-controller causing the valves to

L"                  continually cycle and eventually deplete system

I                  vacuum.  Corrective measures included-.replacement of
L...
                    the early  valve  pits with fiberglass pits capable of


-------
withstanding traffic loadings.   Breather, tubiif;j-*'^-' -'. -"i^;;,.:



extensions above ground and controller modifications




have minimized  these past problems.




      Simply stated,  the early,vacuum systems




suffered from growing pains.   A better understanding




of vacuum sewer hydraulics,  improved' system




components, and established operation and maintenance




guidelines have led  to significant operational




improvements.
                                                    *.'  '-

-------
                   b.

r
L
                          Although operational reliability has improved

                   with  each  successive generation of systems,  some

                   problems still exist.   Six operating systems were

                   visited in 1989 so that meaningful operation and

                   maintenance data could be generated.   An attempt was

                   made  to visit  systems that would give a good cross

                   section of the technology.   Topography,  geographical

                   location,  size,  and -varying design concepts were  '' -

                   considered in  the selection process.   One early

                   system was visited to see if improvements through the

                   years has  resulted in increased reliability.
                                           TABLE
L
PRQJECI_NAME	1

Ocean Pines
Westmoreland
Ohio Co-Phase I
Lake Chautauo.ua
Central Boaz PSD
White House
.UQQAIIQN 	 	 _ f
Berlin, Md.
Westmoreland. Tenn
Wheeling, WVa
Celeron, N. Y.
Parkersburg, WVa
White House, Tenn
DATE
DPERATIONA
1970
1979
3.984
198B
1988
1988
SYSTEM
L TYPE
VAC-Q-TEC
AIRVAC
ATRVAC
AIRVAC
AIRVAC
AIRVAC
                                          30

-------
                   - "" '   ' :" -"-~s :-f*-***:. -if..4'f.'-'" I'^CC^'-^R-iS^Jii^i^-i^r''viv.V -* .'=.
                     Table 19 gives general  information on each

               the systems visited.
                                    TABLE  19
                               GENERAL INFORMATION
                              ON_QPERATING SYSTEMS
L. F. of  Pipe

# Vac. Stations

H Valves

# Homes  served

Topography    -7* - ".

Soils

Community Age

Seasonal Pop. ?

Mean Income
Ocean .
285. 000
12
1500
,3500
^ Flat-
Sandy
New
No
High
"testae
83. 000
4
490
540
Rolling-
Rock
Old/New
No
Middle
Ohio
Qoynt*
43. 000
1
. 20O
250
Hilly -
Clay
Old
No
Middle
                                                    Lake
         Central
121. 000  39, 000

      4        1

    900      180

   2500      350

   Flat    Flat

  Sandy   Sandy

    Old Old/New

    Yes       No

 Middle  Middle
  White
 _Housg

 85. 000
    260

    360

Rolling

   Rock

Old/new

     No

 Middle
                                       31

-------
                               QiSIGN/QQNSIBUCIIQN.DAIA
                         Table 20 shows design and construction data as

                   it relates to the collection systems of each of the

                   systems visited.
                                       TABLE 20
                               DESIGN/CONSTRUCTION DATA
r  -
.
Valve Type


Pipe material


Diameters (in. )

Min Cover (ft. }

Win. Slope

Div. Valve

Thrust Blocking

Multibranches

Longest line (ft)

Design Concept


Pit/House Ratio

Type Sumps
Ocean
PiQes 	
Vac-0-Tec
solvent
Melded
all 4 :
3
none
Plug
No
Yes
Unknown
none
.43
concrete
7OO gal
Weferno.r_
AIRVAC
Model-0
solvent
Melded
3. -4." 6 {'.:*'
4
0.2%
Plug
Yes
Yes
Lin known
reformer
pocket*
.91
2 pit
fbgls
Ohio .
GQynty._
AIRVAC
Model-S
solvent
Melded
3.4.6 .if
3
0.2%
Plug
No
Yes
8. OOO
early
AIRVAC
.80
fbgls
Lake
AIRVAC
Model-S
rubber
gasket
3. 4. 6. 8
4
0.2%
Plug
Yes
Yes
8.500
early
AIRVAC
.36
fbgls
Central
fioag 	 :
AIRVAC
Model-D
rubber
gasket
3.4.6
3
0.2%
Gate
No
Yes
6.500
early
AIRVAC
.51
fbgls/
concrete
White
House
AIRVAC
Model-D
solvent
Melded
3. 4, 6. 8
4
0.2%
Plug
No
Yes
8.200
current
AIRVAC
.72
fbgls
    * Converted over  the  years  to meet "early AIRVAC" design standards
                                          32

-------
                      Table 21 shows design and construction data a


               it relates to the vacuum stations of each of the

               "}"'-:"-"'  '"" -" ' '   .''-?-'  -..;" . ;,.'.. ' :',.:*'"--*-""".," -ttj'"'^- ". '    ' "
               systems visited.'     '  ''"'.''.'".* ***""'
                                     TABLE 21
                            DESIGN/CONSTRUCTION DATA
                                .VACUUM.SIATIQN
Ocean
# Probes          Multi


Equalizing Lines  No


Odor Filters      Yes
Multi


Yes


No
                                         Ohio
                    Lake
                     Single   Single


                     Yes       Yes


                     No        No
Central

toss	

Single


No


Yes
White
House


Multi


Yes


No
                                        33

-------
                           Significant improvements have been made  to  the


 f-                   components  in  the last ten (10) years, particularly


                    to the valve controller unit.   This has been


 .                   attributed  to  a combination of research and testing
 1                                                   ....

                    and an increased quality control effort.   It is


 I                   estimated that this alone has reduced the problems


                    that plagued the early systems by 50%.  Continuing to


 [-                   educate the designers,  builders,  and operators of


 I   .                proper techniques will .result in a further reduction


                    of the problems.   Evidence of this is starting to

 r
 j                   surface in  some of the more recently constructed
 I,

                    systems.


 (.^^                       Operation and maintenance data was gathered on
 W -- - -  -        -|- '-  .*. iLyj*. - '"::- ->  -   -    .-,..'-.-    -.: f- -, -	 -.
 ['                   each of the systems visited.    This data is presented


                    in'Tables 22 through 25.
                                          TABLE 22
                              OPERATION  & MAINTENANCE DATA
                                  _SENERAL_!NQRMA!!QN
     #  Operating personnel


     Other  duties ?

     #  Men  needed for
     vacuum part of system
SYSTEM
8
No
8
SYSTEM
6
Yes
1
SYSTEM
C
5
Yes
1
SYSTEM
0
7
Yes
2
SYSTEM
E
1
Yes
1
SYSTEM
_F
3
Yes
1
P
u

-------
                                   TABLE 23
                         OPERATION & MAINTENANCE DATA
                                 MANHQURS^XEAR


Normal Maint. (hrs/yr)
Prev. Maint. (hrs/yr )
Emerg. Maint. (hrs/yr )
Total manhours/yr.
# of valves
Manhours/yr/ valve
# of customers
Manhours/yr /cust.

SYSTEM
A
16. 640
2,500
1 660
20, 800
1,500
13.9
3,500
5. 9

SYSTEM
_B 	
1,915
245
192
2,352
490
4.8
540
4.4
TABLE
SYSTEM
_ Q
260
10O
240
600
20O
3.0
250
2.4
24
OPERATION & MAINTENANCE
_PQWER_QQNSUMP.TIQN^YE/

.  .-
Power cost/yr ($)
41 of valves
Cost/yr/ valve ($)
# of customers
Cost/yr/cust. ($)

SYSTEM
A
120.000
1,500
80. 00
3,500
34.29
,
SYSTEM
B _
15. 000
490
30. 60
540
27.77
TABLF
SYSTEM
_ C 	 .
2. 400
200
12. 00
250
9.60
25'
OPERATION & MAINTENANCE



of valves
# service calls/yr
Mean Time Between
MEAN TIME
SYSTEM
A
1.500
1,500
1.0
BETWEEN
SYSTEM
B
49O
48
10.2
SYSTEM
D
365
1. O13
48
1.426
900
1. 6
2, 500
0.6

DATA
SYSTEM
_-.> _
27, 54O
90O
30. 60
2.500
11.30

DATA
SYSTEM
E
315
90
384
789
190
4.4
35O
2.3


SYSTEM
E
4.800
180
26. 51
350
13. 71


SYSTEM
. E 	
260
200
60
520
260
2.0
360
1. 5


SYSTEM
____ i
3,900
260
15.00
360
10. 83


SERVICE CALLS
SYSTEM
C
200
24
8.3
SYSTEM
b
90O
40
22.5
SYSTFM
E
180
30
6.0
SYSTEM
F
260
24
1O. 8
Service Calls (MTBSC)
   (years)
                                     35

-------
 r
 I
 '
r
r,
                    c.
   ...  An EPA Technology Transfer  Seminar, Publication^



prepared in 1977, detailed the  failure  rate (MTBSC)



of some of the early vacuum systems.  In  general,  the




MTBSC of the early systems ranged from  0. 06 to 8. 33-




years.  All but one of the systems had  a  MTBSC of




less than 4-years.  8y contrast.  all-of the systems




studied in 1.989, with the exception of  the  early




system,  had a MTBSC of greater  than 6-years. with the




average being approximately 10-years.   This indicates




that component improvements coupled with  design



advancements has had a tremendous impact  on the




reliability of vacuum systems.

-------
       Each of the systems visited experienced some type, of.'".jj :?,"

 problem which predominated' as a demand on Q&M staff time.

 However,  most were short lived.   Tahle 26 describes the

 types  of problems found.

                           TABLE 26
                   _BRQBLEM_QLASSIFIQAIIQN
                      Responsible
Avoidable/
% of Total
Component defect
Design shortcomings
Operator error
Construction related
Equipment malfunction
Extraneous water related
Manufacturer
Engineer
Operator
Contractor
Manufacturer
Customer
Avoidable
Avoidable
Avoidable
Avoidable
Unavoidable
Unavoidable *
40 %
10 %
5 %
25 *
5 %
15 %
    In theory, this should  avoidable  with proper smoke testing,
    I/I analysis and correction  prior toconstruction.
    However, operators  report that  no matter what the effort,
    some amount of extraneous water usually enters the system.
      A sophisticated  statistical analysis was not

performed to develop the above percentages.   The

percentages were determined by a combination  of frequency

of occurance and demand on staff time  as reported by the

sytem operators that were interviewed.   They  are presented

only for the purposes  of putting the different problems

into perspective.

      Assuming the percentages roughly approximate reality,

80% of the problems to date can be categorized as

avoidable.  This does  not mean that they were not or are
                                            *t
not problems.   With good design, construction,  inspection.

training,  and quality  control, however,  these problems can

be avoided in future systems.                          .

-------
c
                          Shortly  after startup of one system,  an unusual

                    amount of  valve failures were occurring.   It was

                    determined that these failures were caused by a

                    broken spring  in the valve controller.   An

                    investigation  revealed that the springs were made of

                    defective  material.  The springs were systematically

                    replaced with  new ones,  an effort that two men

                    accomplished on a part time basis over the span of a

                    month  period.          .

                          This effort did not require the removal of the

                  .  valve  itself,; .  .Using spare parts,  the District put
r -
'                    new springs in  the controller component of the valve

r-                   at their workshop.   After a sufficient amount of

<--                   controllers were rebuilt,  they were taken  to the

f"                   field  where they were simply was put in the place of
i_.
                    the controller  with the defective spring,  a procedure
I"
                    that took  10 minutes per valve.   These defective
                   controllers were then  brought  back to the shop where

                   the procedure was repeated  until  all  controllers were

                   rebuilt with the proper  spring.   This, problem has not

                   since returned.

-------

       The  original valves in one system had a




controller that was different from the ones used




presently.   They were  found to be very unreliable.




The result was  more valve failures,  and h=?noe,  more




O&M expense,  that originally anticipated.




In the 1970' s,  AIRVAC  designed and patented their own




controller.   After the successful testing of these




controllers at  their Indiana facility,  they began




mass production.    ' .    '




       Every valve in the  system has since been




retrofitted with the AIRVAC controller.   The failure




rate has been greatly  reduced since the changeover. '
      Some valves were found  to  cycle  more than  once



after the sump was emptied.   A redesigned  controller




shaft and seal has solved  this problem.  Controllers




with the old 'shaft and seal have been  retrofitted




with the latest version.'
                       39

-------
                          The type of division valve used in most




                    operating systems is the plug valve.   Some systems




                    have experienced major problems with plug valves




                    while others have not.




                          Problems reported in one system included times




                    when system vacuum pulled the division valve closed




                    thereby cutting off system vacuum beyond that point.




                    As workers attempted to re-open these valves.




                    frequently the valve shaft was twisted off due to the




                    heavy load applied by system vacuum.   When this




                    happened,  the division valve could not he opened




                    resulting in part of system being out of service.




                    until corrective measures were taken,




        I            .   .   Some system operators reportedI. problems with




I                    plug valves not holding vacuum when closed.   This




                    renders them useless as troubleshooting tool,  which




!                    is their primary purpose.
f
C
                          Problems with plug valves have been attributed




                    to quality differences between manufacturers,  in some




                    cases,  and to defective materials in others.   Plug




                    valves without these qualities can and have been used




                    successfully.




F                         Some recent systems have used rpsilri ent-wedge




                    gate  valves instead of plug valves with much




|                    success.   With proper care in selection process, both




                    types of  valves can successfully be used.




'^P



r                                          40

-------
L,
                         Some valve failures  that. occurred af'ter startup




                   of one particualr system Mas  caused by de-feotive




                   tubing in the controller.   These tubes were




                   systematically replaced with  new ones. "  This problem




                   has since not re-ocurred.
                                          41

-------
                               _QgIGN_SHQRIQQMIN6S

[
F
                                                    *"",* LV "**/ ^    .'..
                                                    "\  "I"* * *:"  '..,
                          Some systems have reported  problems with sewage

                    discharge pump cavitation.   This  is due to the antual

                    characteristics of the pump  itself.   A vortex plate

                    installed in the bottom of the  collection tank is one

                    method of correcting this problem,  assuming the pump

                    has already been installed.

                          The real solution lies in proper design.   Net

                    positive suction head (NPSH) calculations should be

                    done.   Section D of this Chapter  discusses these

                    calculations.    A pump having sufficient NPSH

                    avail-able should be selected. -.....;- . ..... .  ->
 r                                _Lea!
-------
                                    .





       One  of  the  newest  systems  in  operation  was   ., 




designed with the most recent  design guidelines.




which  are  more conservative  than in the  past.   This




resulted in larger vacuum pumps  than would be




selected using the old design  standards.   While this




additional capacity has  helped in terms  of system




pumpdown  time, it also  has  caused  a small problem.




       The  vacuum  pumps appear  to have  sufficient




capacity to keep  up with an  open valve.   This being




the case, low vacuum is  not  recorded at  the station.




even though it is occurring  at the  location of the




open valve. In addition, the automatic telephone




dialer is not activated.  This results in increased




run time of the vacuum pump  and  increased power _-




casts.   In order  for the problem to be noticed, the-




operator must be  very observant  when analyzing the




daily vacuum  charts to notice  that  the pumps  are




cycling more  frequently  than normal.   Otherwise, a



valve that is hung open  may  go unnoticed for  days




resulting in  a waste of  power.




      A simple solution  to this  problem  involves




installing another relay in  the  control  wiring that




causes the dialer  to call the  operator if both pumps




are running together for a predetermined amount of




time (say 1O  minutes),  despite the  vacuum level.
                       43

-------
                      '  -.  -.  ,--..  .; - :  - . -...:-X--*-*..v.>.-.,-. -~- *,- .....  .
                    '..-'   .  ' :.- ''."-' ''"":  -''*  f"^-' ' ;.' *'f :*"'* .'>''...- ."-.--'


                          _as9e_eyllgd_into_yacuym_eym.e


                           A high sewage level in the collection  tank can


                    be  caused by pump failure (usually control related


                    rather than  actual pump malfunction)  or hy more flow


                    coming in than the sewage pumps  are capable  of


                    pumping out.   The system design  normally calls for an


                    automatic shutdown of both vacuum and  discharge


                    pumps in  the event of this happening.   Some  systems,


                    however,  do  not have provisions  to prevent the


                    automatic mode from being overridden by manual


                    operation.


                           The natural, inclination, when faced with a ssero


                    (0) vacuum situation,  is for the operator to manually


                    operate the  vacuum pumps in an attempt  to restore


                    system  vacuum.   Doing this with  a  full  collection


,-.                   tank  can  result in sewage being  pulled  into  the


-                    vacuum  pumps.   This can  result in  damage to  the


f                   vacuum  pumps,  especially with a  sliding-vane type.


                          The proper procedure,  assuming the discharge


J                    pumps work,  is to valve  off the  incoming lines and


                    turn  the  vacuum pumps  off.   The  discharge pumps are


!-                   then  used to  pump the  col lection tank down to  th


f                   normal,  operating level.   The line  valves can then be


                    opened  and the vacuum  pumps returned to their


                    automatic  mode.   Good  design will  include electrical


                    provisions to prevent  overriding the automatic: mnde

' .^^^^
                    without these steps first  being  taken.


                                           44
[

-------

      Line breaks,  caused by  a  trench  settlement,




were most likely  the result of  inadequate  bedding




materials or poor compaction  during  construction.
      There have been cases of loss of system vacuum




due to broken fitti.ngs.  In all but  few cases, the




failures have occurred at fittings at or near the .




valve pit.  This is most likely due to insufficient



compaction around the valve pit coupled with system




rigidity due to solvent welded fittings.
                       45

-------
 [
[
r
 ^
[
c
[
                                                                           *
                          Most systems experienced problems shortly after

                    start-up.   Construction debris (stones,  small pieces

                    of  pipe,  etc)  in  the homeowner' s building sewer

                    causes the vacuum valve to hang open until  manually

                    cleared.   These problems usually disappear within a

                    few weeks of startup.   Problems of this nature are

                    easily discovered by the operator simply by listening

                    to  the auxiliary  vent.   Hearing the constant rushing

                    of  air is a good  indication that valve is hung open.

;                    Opening the valve pit,  unscrewing the valve body and

                    clearing the obstruction is a  10-minute procedure.
i

                         Temperatures  approaching  175  degrees  were

I                   reported in one system shortly  after  startup.   The

                   hot air from the vacuum pumps was blown  directly at

I                   the motor control center  (MCC).  The  extreme  heat

                   caused relay and starter  problems in  the MCC  which

                   resulted in pump and telephone  di.aler malfunctions.
                                           46

-------
r
r
      An analysis of the situation revealed that the


vacuum pumps.were Mired incorrectly.  Rather than the


pump fans coming on when the temperature reached 50


degrees and remaining on until the pumps turned off,

                                               
-------
                              .E9U!PMEN!_MALFyNC!!QN
 L.

 ,                         At one system,  a problem with one of" the level

 I                   probes occurred.   The probe failed to send the proper


 r                   signal to the motor control center to turn the vacuum


                    pumps off during periods when high sewage levels

 j                   existed in the collection tank.   This resulted in

                    sewage being pulled into the vacuum pumps causing

                    damage.   Another time the probe failed to send the

 p-                   proper signal to the motor control center to turn off

 '-                   a discharge pump.   This resulted in the pump

 f                   continuing to run until the tank was dry.   The


 ^P                problem was traced to a faulty transmitter which was
 r-*
 |
 i                   replaced.


                          Since failure of the probe can lead to the


                    ruining of a vacuum and/or sewage pump,  the operator


                    developed a simple inexpensive backup system.   This


                    involves the use  of a magnet strapped to the site


!                   glass above the highest set point of the probe and


                    one below the lowest  set point of the probe.   A

L-                   third,  float mounted  magnet,  held inside a plastic


f                   tube,  moves with  the  level of the tank inside the
L_
                    site  glass.   Should the probe fail and the level  rise

r~
:                    (or fall)  beyond  the  last set point,  the two magnets

                    will  meet  causing a circuit to close and the


                   appropriate pumps to  either start or stop.

                                           48

-------
      At one  system  the  automatic telephone dialer




malfunctioned by  calling the operator only to report




that the system "was all clear".   Investigation of




this problem  revealed that  interference from the




motor control center,  caused by electrical spikes,




was sending false signals to the dialer.   Shielded




cable added to the dialer Miring did not help.   The




dialer was taken  out of  the MCC and mounted on a




nearby wall.    This corrected the problem.




      It is now known that  the  microprocessor based




equipment is  very sensitive to  power spikes.




Provisions should be made during design to filter the




power supply  or to provide  a separate "clean" power




supply to this kind  of equipment.    .   .
      A big problem in one of the earlier systems  has




been the inability of the telephone dialers  to




function properly.  Without -a dialer, which  provides




24-hour a day coverage, problems go unnoticed until




the next work ..day.  While this has reduced the  amount
                       49

-------
r
r
                    of overtime significantly, it has  also  resulted  in

 u                   increased run times.  .The operating  personnel .     '.

                    apparently feel that the system is reliable  enough

                    (i.e.,  oversized vacuum pumps can  keep  up  with a

 i                   valve failure) and valve failures  are so infrequent
 L
                    that replacing the dialers cannot  be 'economically
 r ''
, 1
 |                   Justified.

 r                         The above rationale may be a case of falsw

 '"                   economy.   Allowing a low vacuum situation  to go

 j                   undetected for hours will result in  unnecessary
 L
                    additional  run time of the vacuum  pumps.   This will
 r   .
 j                   result in increased power costs as well as -increased

 r-                  wear on major equipment.   This increased wear leads
 t
 1                   to decreased equipment life.   A high sewage  level in

 [                   the collection tank typically results i.n total system

                    shut-down until the operator corrects whatever is

                    wrong.   With no-dialer to notify the operastor of

                    this situation,  the system may be  shutdown  for  hours

                    at a time.   This will lead to waterlogging,  which

                    will require a significant labor effort to correct.

                    Even more serious is the liability potential that
r
I                   exist as a -result of damage done by  system backups
i .
                                *                *
                    into the-customers homes.   For these reasons. 

L                   telephone dialers are considered to  be  an  absolute

f"                   must component in the vacuum station..
(j                                          50
L

-------
                ern _water logging
      One of the most severe problems  that  nan




occurred with the collection system  is loss of  vacuum




due to "waterlogging".  This occurs  when  sewage is




admitted to the system with insufficient  atmospheric



air behind it.   (See Section F. 6  for a discussion on




waterlogging).   The result in ever decreasing vacuum




levels beyond the waterlogged section.  This may lead




to insufficent vacuum to open the vacuum  valves and




ultimately to sewage backup in the home.  In most




cases, waterlogging is caused by  too much l.iciuid




(extraneous water) entering the system at one time.




This is a very dif -f icult problem  to  address since it




typically is related to illegal and  difficult to find



storm sewer connections by the customer.  An




aggressive I/I program wiJ 1 keep  problems such  as




these to a minimum..
                       51

-------
                          Component  defects have been responsible for

                    many of the valve  failures in the pant.   With these

                    failures being drastically reduced by component""
 u.
                    improvements, one  of  the remaining ways for a valve
 f- 

 j       '            to fail is through water in the controller.   Water in

 r                  the controller will prevent it from completing its

                    cycle and the valve will remain open.   This problem

 [                   is more likely to  occur with the A1RVAC Model "S*
 i .
                    valve than the Model  "D"  valve.  (See Section D. 4 -for

                    a discussion on  Model "S*  and "D*  valves. )

 ,                         In either  the Mod'.l  "S"  or Model "D*  valve,

 *-                   water can enter  the controller in two general ways.

 f                   In the first way,  water that is present in the upper
 LA
 ^P                valve chamber enters  directly into the controller as

 i                   a result of the  controller not being air and/or

                    vacuum tight.   A tightness test is normally done at

                    installation,  during  the  annual preventive

 f                   maintenance,  and any  time  emergency maintenance is
 j

                    performed on the valve.   The other possibility is
 r
 :                   through condensation  in  the breather tubing.   A

 r-                  properly installed  breather line,  with a drain

 -                  leading to the valve,  wi.l 1  prevent this second case

 f                   from ocurring.
L<
rr                                          52
L.               "                ' .  .

-------
      With  the  Model  "S*  valve,  a third possibility




exists. In  this case,  water comes directly From the




lower sump  to the  controller.   The Model "S*  valve




requires a  watertight  seal  between the upp*r and




lower sections  of  the  valve pit so that a bubble nf




air can he  trapped for use  by  the valve controller




during its?  cycle.   Should the  sea] be broken and




water take  the  place of air, it will be drawn into




the controller  by  vacuum when  the va'l ve cycles.
                       53

-------
W':':*?K#^
      ,-   - '."-.-'.'>/;->;;:.*
 1..          ...-..-..  .*-.*<'.;*.F
   . '  .  V   -  *',''' -r T.:
                                                                  i'^,\.^/p*-5^.J*i^r -^*t ^J  
                                                                  ^%!^^;;

                                                                  ^^iS*!-1^'^-'-"".'
                                                                  ^."11 wVf'i ".r^fe^ -2^r  A't^j-*.-

        
          -  ".    --"v-"-:
f"^^:::^^r/^?^%^^
^nM:^- tv^vv.---:^^.'..^ -^r-^xir.^
tLJ^i.^"-?': - "^'-lV>iv??^sS
                                                                                 --

-------
                    SECTION

                __X__I_E_M	C_g_
 1-
      Certain site conditions make conventional sewer

installation expensive.   These include unstable soils,

rock,  and a high Mater table.   In addition,  restricted

construction zones or areas that are flat may also carry.

high  construction costs.   By using vacuum sewers, the

construction costs for these difficult conditions can be

reduced.   Smaller pipe sizes installed at shallower depths

are the prime reasons for this.   The uphill transport . C< .
capability,  even  when used only to a very small degree, may

save many dollars in  installation costs.   One other major

advantage is the  extent to which unforeseen subsurface

obstacles can be  avoided.   Each of these considered

individually" results  in lower"\costslf;' Considered   '    '"..-,
              '.-'      '  -.:>. ~  :A>^./;>,*&-VS-.-VV> :  ' '   '- .   ..:".. ' .'
collectively, they may result ip.substantial cost savaings.

     There are  three  key costs  that will materially effect

the price of a  vacuum system: the vacuum station,  the pipe.

and the valve pits.   The price  of the vacuum station

depends very much on  the equipment selected,  the type of

structure it is house in.  and the amount of excavation

required.  The  pipe installation prices depend on pipe

diameter, trench  depth,  and soil conditions.   Valve pit

costs will vary depending on the type of valve,  type of

pit, and depth  of pit.   These three items typically make up

6O-8OX of the total bid.   The remaining items include

appurtenances,  testing,  and restoration.

-------
                   Many factors  affect construction cost bids.  Material
                                                                   
              surpluses or shortages,  prevailing wage r.ates^  the" .local..." ,
                      - ,: ':"; :^'a; .: >-. '&. -'? -T  - :"i;. ^r-'^^^&^;-.?$^&
              bidding climate. ' geographic area; ' time of year,  -"soundness-^

              of the design documents and the design engineer.' s-

              reputation are examples of these.   As such,  it  is
i"                                                                  - ^

i              impossible to accurately predict construction costs on a

* '            nationwide basis.  Using sound engineering practices.

              however, the engineer  should be able to make a  fairly

              accurate estimate  of the construction costs.   The following
                                                       .-.,--.
              steps may be of  some value for engineers considering vacuum

[              sewers for the first time:                    -   ....;..
                    Analyze bid tabulations of other vacuum projects.  It
                    is desirable to use  a  project that is in the same
                    geographical area and  having similar site conditions.

                    Request a set of plans and specifications in order to
                    gain a full understanding of what each bid item  . 
                    includes. .  Ask about any peculiar or unusual bidding
                    conditions.          '  :          '-,..'. -..'-:.
                      --  :. ***?:.--' -.- ":--  t?>   .   . ____ - . :.,  . ..t.v-^-y viii--.^--'.'-u. -   -, .  
                    Estimate * the cost of the system by" "applying" modified
                    unit prices that take  into consideration the locale
                    and site conditions,      '               _.'-.'

                    Correct for inflation  by applying cost "indexes.
r                         .,  .  

                    Because of the many factors that influence a bid. it
i
              is difficult to say if the above  procedure will yield

              information of quantitative value. ' although qualitative

              assistance is possible.  Quite  simply,  the project will

r             cost what the low bidder feels  it will cost.

 

-------
       It is not  uncommon -For  a  wide range of bids to be


received on an engineer's 'first -vacuum projecti",.-..-
    .; ,-"4..-" "~ir ?,~i^*^*&.'*-^'-?;'?'''' -'J-..;--: - **.;*-. y ;> Y..."?/..-V" ' '
       "   '" '.';;>' :"'-"'A-"'-:'r  v" *" '*?*'?->',?*' " '   ' ">>-"' ''    '*.  ' .
Contractors -unfamiliar 'withT~vacuum sewers may  bid l-iig


simply because of  the fear of the  unknown (e. g. . bid as if  


the  project was  a  gravity sewer).   Equally  passible is a


contractor who bids too low because of an underestimation


of the effort required (e. g. , bid  as if it  was a water


line).   Usually  the cost is somewhere between  these two


extremes.   Once  the contractors have experience


constructing vacuum sewers,  the spread between  low and high


bid  diminishes.  It then becomes much easier for the


engineer to estimate the construction costs of future  .'-,


projects.

      Most engineers are capable of estimating capital

               '                 ^                  .         . 'i
costs in their geographic area  of  practice  once  major  : *'
                              -^   -;          ,                  
material component costs are  known.  . Installation costs can

      ->;". * *- *  .."-***-/''';-"- * v ^4, . rt*  .'-\ '-***.- *'?' ^**:.**V;.:,  -s-*; *";. ' >- .  -'   - _ i ;T"     .*.'-.%*,
be developed by  analyzing the effort required  to install   "


conventional- technology and applying the appropriate


modifications to the unit prices to correct for  the local


site conditions.             .
 **.'."-

-------
 r    "   -
 L            2.    Qeerstion an.
 .
L
E
                   ' Thi"'"oh\/;i"rjR *rl\/*in'fc.aais fcn uti'l -i SM na'^x/jtr-ijum "jseweK-s "i *''-*"
 r
                   Therofavxbus ; advantage 'to utilizing"'* vacuum'"sewers -is--a'-




             savings  of capital costs:'  This 'savings, however,  may come




             at the expense of higher operation and maintenance (O&M)




             costs.   The question then becomes, "Is the savings of




r            capital  cost enough to offset the increase in O&M




             expenses"?  A present worth analysis, where life cycle




             costs are  converted to present values, will answer this




             question.   This analysis,  however, is only valid if




1             reasonable capital  and O&M cost figures are used.




r                  Very little historical cost data exist 'because  of the




             relatively new nature of the vacuum sewers.  This  is




;             especially true for operation and maintenance costs.   This




             lack of  data has led'many to the conclusion that vacuum'"
             sewers must be  O&M intensive.   A review of cost records  of




             operating systems  suggests that previously published O&M




             figures no longer  apply.   Reasons for this are twofold.




             First, the previous figures were based on very limited data




             on a few early  systems.   Second,  component improvements  in




             the valve have  resulted in significantly.fewer service




             calls, and hence,  lower O&M costs.   These factors render




             the previously  published data obsolete.

-------
                    Information gathered "from the systems that were -

              visited in 1989 is presented in the -following sections. .T,.
                    ;;  ...-,  . -''-^ .^ v>?\V;vrwj-- .'
              Data -from the Ocean- Pines"" system :"i;e" not included since" this

              system is not representative of the current state of vacuum

              technology.
r-
                    Table 27 shows typical  Q&M cost components.


                                        TABLE  27
                              _IYPICAL_Q1,CLCQI_CQMPQNENIS
                    Labor
              *     Clerical
              *     Power
              *     Utilities
              *     Transportation
              *     Supplies/maintenance
              *     Misc.  expenses
              *     Equipment
              *     Future connections
                    a-
                      Normal,  preventive. & emergency
                      Billing
                      Vacuum & sewage pumps
                      Water,  phone, fuel          - s- > .
                      Vehicle amortization, fuel. ins.
                      Maintenance contracts
                      Insurance,  professional fees
                      Renewal and replacement
                      Set-aside amount (if required)
     .. Labor costs are estimated by multiplying the,

number of manhours required by the hourly rate, and

adding fringe  benefits.   The annual manhour

requirements are made up'of normal,  preventive, and

emergency maintenance.  "'.-                  "  "

      For normal maintenance,  an operator is not

required 24 hours a day to monitor the system, as the

telephone dialer does this for him.   However, someone

must be available around the clock in case the
                                   \
telephone dialer calls with a problem.   In this

respect,  vacuum  systems are unique.   Very few

problems in a  vacuum system can go uncorrected for

any length of  time without causing a cumulative

effect.

                       .  5 '      

-------
      The operating entity's' overall  fesponsi.bi.l3.ti.es


should be considered when estimating  the  labor
 [~


                     costs. "; For example., the entity may' also be
j

r
                    responsible for other sewer facilities,  or possibly


 _                  even  water facilities.   In these cases,  operating


 L                  personnel  are usually shared.   At the end of the


   '                 year,  the  time charged to the operation of the vacuum


                    system most likely will relate exactly to the effort


 !                   required (e.g.,  one (1) hour per day plus some hours


                    charged to emergency maintenence).   If the overall
 r~

 [                   facilities are large enough to warrant different


 r                  shifts, emergency work most likely will be done

 i                          '              '         "' 	"
                    without overtime being required.


 f                         An entirely different situation exists for the


                    entity operating nothing but a similarly sized vacuum


                    system.  Typically a full time operator is hired.


                    This' man charges 8 hour's a day to the maintenance of


 '-                  the system although most days he will spend much less


 f                   than this.    Should a problem develop after normal
 1..-                      '."      "              ----..     .._
                    working hours, he most likely will be paid overtime.


                    Even though both operators will spend the same amount


 p                  of fltual_meiQteQfiDEe_ti!!e,  the amount of b.illed._fcime


 L-                  will be entirely different.  . The engineer should


 f                   carefully  analyze the  client* s overall operation,


                    taking into  consideration the possibility of shared


                    duties, prior  to making an estimate o"f the labor


                    costs.

-------
      Preventive maintenance is usually scheduled to

be done by the  normal work force during off peak .;.

working hours. -  Because of this,  preventive ;'.:;-.'-^isSi?^-,

maintenance is  usually reported as normal         :

main ten an ce.

      Emergency maintenance many times requires

personnel after normal working hours.   The result is

overtime pay.   In addition,  emergency maintenance

typically requires two men.

      Table 28  gives  a range of manhoure required per

year as a function of the number of vacuum valves.

This table was  based  on data from the systems that .

were visited in  1989.  As such,  the values shown

should be considered  as realistic values for new

systems with proper design,  construction,  and    ""''

operation.
                        TABLE 28
              MANHOUR ESTIMATING FACTORS
          NORMAL

          PREVENTIVE

          EMERGENCY
LOW

0.4

0.5

0.2
3.9

1.1

1.2
AVE

1.7

0.7

O. 6

-------
 r
 L.                        When  a  full time operator is to be hired,

r                    regardless  of anticipated work load, the values  in
                                      "''.: ":~- " '." '!'**?''':':         '    ''"'-. '''.&'
                    Table 28 should not be used?'":" In this casesV; the ""-r' ' -*-'*'
I
r
                                                                            'i ~v:--
                    estimated annual manhour  requirements should include

                    the full time hours of employment plus an estimate of

                    the overtime (emergency maintenance) hours,  taking

P                   into consideration overtime  work generally requires
I
                    two people.   No allowance is needed for  preventive

                    maintenance since this can be done during normal

                    working hours.

(                          The following formula  can  be used to estimate

r-                   annual labor hours for these cases.   This formula .
t   '
                    assumes a 40 hour work week  and  that some of the

                    emergency maintenance will occur during normal

                    working hours.
                         .                ,.   ..,.                   .  %
                    2080 hrs/yr +  (.75  x Emergency factor x 8 valves x 2)
                                No. of valves    :   200

                                Emergency  factor:   0. 5
                        Annual labor hours  =  2080 + (. 75 x 0.5 x 200 x 2)

                                            =  2080 + 150

                                            =  2230

                                            8

-------
b.
Clerical
  .-,.-  * jit    r:^'^^-:^*^:*^^-'" '*  .-
    "'   This ' "xtenis includes wages* for* tihe'clTerical'^.?-?'''.,
staff.  Also included would be the billing costs  such
as envelopes and stamps.   Like labor costs,  the value
of this item most  likely Mill depend on whether the
operating entity has an existing,  on-going operation
which  requires office staff.   If so, the costs would
be limited to the  direct billing expenses only.

-------
                   c.
                   :"     Power  is  required 'for the vacuum pumps,  the""""

                   sewage pumps, and  for  heating and lighting of the
i.
                   vacuum station.    Once the  design is completed,  it is

l_                  possible to  estimate the  annual power consumption

f                   with a high  degree of  accuracy.

                         Power  costs  for  the pumps are estimated by

                   using the following general formula:


[                                p = T  x H  x .746 x C

                         where  P = Annual power cost -
r                               T = Time of operation (hrs/yr)
;                                H = Horsepower
                                C = Cost of electricity ($/kwhr)


'                         This formula does not include any surcharge the

[                   power company may  assess  on peak demands.   The local

                   rate. structure  of.  the  power company should be

                   analyzed and an appropriate surcharge estimated.

                         The capacity of  the vacuum pumps, ' and the

                   resulting horsepower requirements,  can be determined

                   by using the formulas  in  the Section 0.   Likewise,

                   the run time of the vacuum  pumps can also be

                   determined.  An  allowance, typically an additional 1O

                   to 20 X,   should be made  in the run time to account

                   for leaks,  breaks,  and valve failures.'"
 ^

[
                                          10

-------
       The  capacity of the  sewage  pumps,  and  the

 resulting  horsepower  requirements,  can  be  determined

 by  using -the^formulas in the  Section  D.  JRun time is

 estimated  by the following formula:

             T =  6. 08  x F/0

     where  T= Time of operation  (hrs/yr)
             F =  Average daily flow (gpd)
             O =  Pump  capacity (gpm)
       There  are  also  power costs, for.  heating.

 ventilation  and  lighting at the vacuum  station.

 These  generally,  amount to less than  $50 a month.

       For  planning purposes,  values shown  in Table 29

 can be used  to estimate the annual power consumption

 for the entire vacuum station.  These factors were

 derived from information obtained from  the systems

 visited in 1989.

                        TABLE  29
           VACUUM STATION  POWER CONSUMPTION
    ... -    _. .   ESTIMATING  FACTORS... v_    ,v
                    LQW       HIGH        AYE

                    160        460        250

      It should be noted that the high  factor  was for

a early vacuum system that was designed under  the

reformer pocket theory.  This design concept results

in a sealed pipe bore during*, static conditions,  which

is less efficient method of  conveyance.   The average

figure is a more accurate representation  of the  power

requirements of recent vacuum systems.

                       11

-------
                    d.     Utilities

                            ."''- *              '                       ''
                    ''  Utilities at the vacuum station generally  :.V," .".

                    include water,  phone and fuel.   Water may be required

                    for sinks,  hose bibs,  or toilets.   A telephone is

                    required for the fault monitoring system.   Some

                    systems make use of cellular phones,  while others use
                                                    .
                    radio communications rather than a,telephone.   Fuel

                    is required for the standby generator.   The cost of

                    these utilities generally is less than $50 a month.
                    e-
                          Vehicle expenses to maintain the system will be

                   incurred.   For estimating purposes,  a mileage rate

                   multiplied by the estimated annual miles will

L                  suffice.   This rate should include vehicle

f                  amortization,  depreciation,  taxes and similar

                   expenses.   Mileage will be required for the following

I                   tasks :
L.

t
L                     *   Daily visits to the vacuum station

j"                     *  . Annual visits to valve pits for preventive
i                          maintenance
i._

r                     *   Periodic emergency maintenance
                                           12

-------
 f.
      As with a conventional system, certain supplies




will be required.  Restocking of spare parts and




inventory is included  in this item, as are ail,




fuses, charts and chart pens.   Initial purchase of




items on quantity discount should  be maximized to




take advantage of the  lower unit costs when compared




to subsequent prices for replacement.




      Service contracts for emergency generators as




well as fuel for the generators is also included in




this item.
g-
Miscellaneaus_exEenses
      Miscellaneous expenses include insurance on the




system structures as well as professional services




(engineering, accounting, legal) that may be required




during the year.
                       13

-------
                    h.
                          An annual set aside account should be      .%.-:'

 j^^                established to generate sufficient funds for  major
 i
 *                   equipment renewal and replacement.  The annual cost
 i
 I                   is estimated by dividing the replacement cost by the

 (                   useful life.   This amount is generally set aside in

                    an interest bearing account until needed.  Present
 t
                    dollars can used in the estimate since the interest

                    earnings most likely will offset inflation.

                    Altenative methods dictated by regulatory agencies

                    also can be employed.

                          Table 30 lists the major equipment items,  and

                    their useful life.
r
E-
                                        TABLE 30
                                                 .AQEHiN

                                                       USEFUL
                          	HEM	
                          Vacuum pumps               10 years
                          Sewage pumps               1O years
                          Vacuum valve rebuild        6 years
                          Misc.  station equipment    10 years
                                           14

-------
 3..
       The costs  of  future  set-vice" connections may'"




 have  to be  included in  the O&M budget.   Unlike




 conventional systems, where a  future connection may




 be relatively  inexpensive,  a future vacuum connection




 can be quite costly.  The  costs of a valve,  valve




 pit/sump, fittings,  pipe,  and  labor may approach




 $2, 000.




       Most  systems  that were visited simply charge




 the future  customer the cost of the connection.   This




 does  not appear  to  be a problem,  since most new




 houses would have a similar expense for an onlot




 system.  In this case,  the annual operating budget




 does  not have  to include a line item for future




 service connections.




       In West  Virginia,  however,  this is not the




 case.   Sewer utilities  are regulated a Public Service




 Commission.   This agency will  not approve a tap fee




 greater than $25O,  regardless  of the type of system.




 For this reason, the operating entity must include




 the cost of future  connections in their rate package




 as an  annual setaside.  The total installation cost




 is discounted  by the $25O  tap  fee and multiplied by




 the number of  estimated annual future connections.




 Since  some future customers may be able to connect to




an existing valve pit,  a sharing factor may be




applied.   This method,  in  essence,  requires present




customer to subsidize the  cost of future connections.




                        15

-------
 r    "                              -
 L-                  A modification of  this  concept includes

 f~~                  a set amount of future  connections in the

                    construction capital budget,  and adjusting the annual 

                    set-aside amount accordingly.   An example calculation

 _.                  of this set-aside  amount  follows:

 t.
                          # vacuum customers          140
 T~                        # vacuum valves             110
 [                         Sharing factor               78%'
                          20 year growth rate          15%
 r                         Cost of new  service      $2. 000
 '                         Tap fee                  $  250
 1                         U prefinanced connection     8

 f
 1.                         4t of future  customers      = . 15 x 140 =  21
                          # of future  connections   = . 78 x  21 =  16
 r                         # prefinanced connections =           _ 8
 I                                             -                      8


                          Net cost of  connection     = 2, 000 - 250  = $ 1, 750
                          Total Set-aside required  = 1, 750 x   8  = $14, 000

 f"                        Annual set-aside required = 14, OOO/20   = $   700
[
[
                                           16

-------
 3.
Usgr.
       To generate sufficient revenues to offset expenses.

 the operating entity must develop a user charge system.

 Components of the annual budget are:

             * O&M expenses

                Labor
                Clerical                .    .
                Power
                Utilities
                Transportation
                Supplies/maintenance
                Miscellaneous expenses
                Equipment renewal and replacement
                Future service connection


             * Debt Service


       There  are many different methods of developing

rates.   A  common  method  includes a charge based on  metered

water  consumption, with  a flat rate for nonmetered users.

The rate structure may be the same for all usages,  or  may

decline  as water  use increases.   Others simply  charge  a

flat rate  for all users.   No matter what system is  used.

the rates  must be sufficient to generate the required

revenue.

       Most tariffs include provisions for tap fees.  These

generally  cover initial  users of the system as  well as

future users.   The initial tap fees are generally used to

cover  startup expenses.   Tap fees for future connections

are used to offset all or part of the actual, cost to make

the connection.
                             17

-------
 C
 [
      As an example, the projected annual operating budget

of a project in Meet Virginia is presented below.  This


project is scheduled -for construction in 1991, with


operation to begin in 1992.  The project consists of a


hybrid collection system (vacuum,  pressure,  and gravity)


and a treatment plant.
                                GENERAL PROJECT INFORMATION
                                            FOR
r
I

-

Construction costs ( $ )
Number of customers
ANN

VACUUM
PRESSURE/
GRAVITY
1. 000. 000 1. 000. 000
140 160
r
TABLE
UAL.iUDeEI
31
TREATMENT
PLANT
750, 000
300

IQTAL
2. 750. 000
300

PRESSURE/ TREATMENT

Q&M
Labor
Clerical
Power
Utilities
T r an spor ta t ion
Supplies/maintenance
Miscellaneous expenses
Chemicals
Equipment R&R
Future service conn.
TOTAL O&M
Debt Service
TOTAL ANNUAL BUDGET
V.A.QUUM

3. 50O
460
2. 20O
750
1,400
1.500
1.000
0
1.600
_2QQ
13. 130
16.65
29. 785
GBAVIJY.

2. OOO
540
2, OOO
500
200
2OO
500
0
3, 100
g
9. 670
ig^g5
26, 325
PLANT _
~'~.
14. 300
0
6.900
750
400
1.630
2,OOO
1,200
2,200
	 Q
29, 380
12^710
41. 090
IQT.AL

19, 800
1,000
11. 1OO
2,000
2,000
3. 330
3, 500
1.200
6.900
-1^350
52.180
45fcQlQ
97, 200
                                          18

-------
                                                                                                J -"T'i:.*.-?r^:_i<-
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                                                              *:
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                                                                                   *<&
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irms^
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             J14..MU=2^*>'.
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 :~  v ./--...:3?'*---s:/*.*-/
    ./-,.. x.i '  ' -r'j*" ;j'W?'1^1
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                                                                                           L^-^
                                                                                                       S^J^^T-:* "
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                                                                  '2HS-TJ

-------
r
                   S E C T I 0 N
                                                H
                  .        .    ..
               ;^
                                                          -     -    

                                                             '  "
1-
                   dgrneowner
                   Factors such as topography,  location of existing


             utilities,  and construction constraints dictate the routing


             of a sewer.   Many times this results in main line


             construction within private property.   For service lines.


             the construction.is almost always within, private


             propeerty.   For this reason easements are required from


             property owners for the installation and future maintenance


             of the system.   '                    -.-'...





                   Generally,"" the user* s responsibility "-begins at the"'" -


             vacuum pit  stub-out.   The length of stubout is usually 6


             to 10 feet.   Shorter stub-out lengths are undesirable.


             They would  require the homeowner to excavate closer to the


             valve pit to connect to it,  possibly damaging the pit or


             disturbing  the backfill/compaction around the pit in the


             process.
             !!!!!!!!!!! M !!!!!!!!!!!! H !! M !!!!!!!! M ! M !! M M !!! M


             SOD DISCUSSION ON  HISTORICAL EPA ELIGIBILTY
                                                                            *

-------
       Most, operating entities require the homeowner to  -.  .
        .\ /: '&'
                     '                     
 replace the building 'sewer -from the house foundation to the :


 stub out connection.  .The reason is simple.   Vacuum sewers


 are not designed to handle extraneous water.   By accepting


 old. possibly  defective building sewers,  the operating


 entity  is taking a risk on operation and maintenance


 problems,  particularly  "waterlogging". .


      The building sewer is temporarily  under vacuum during


 the valve* s open cycle."  For this reason the pipe material


 must be able to  withstand those forces without collapsing.
It is standard practice for 4-inch,  Schedule 40.  SDR .21, . or


SDR 26 PVC pipe  to  be used for this purpose.   Fifteen


hundred pound (1500-lb) crush-type pipe is not acceptable.


nor is SDR 35 PVC.   '^: * :                  '


      The homeowner also is responsible for the


installation of  th4"""auxiliary vent.   This vent is  '""""	


necessary for the proper operation of the valve.   It should.


be located no closer than 20-feet to the valve pit.   It is


desirable for this  vent to be located against a permanent


structure, such  as  the house itself,  a fence,  or a wall.


      There have been attempts by some engineers in the


past to include  this work as part of the construction


project.  This was  -found to be unworkable,  as this required


the complete knowledge of the homeowner1 s plumbing system


prior to the project bid.   Many times,  the homeowner was


unsure of ,the exact location of his building sewer.


Contractor liability was increased since excavation near


the foundation was  required.   This led to high unit bid

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~             prices.   Finally,  installing a vent on the  building sewer
I        -            -... ....-..-...     ......     .    ......
I                    "  .,':   .-.,:  =

              before the system was ready for operation did nothing more



              than vent the septic tank, which created odor problems.



^             All of the work required by the homeowner is  to be



i              inspected by the operating entity  prior to  final



p '            connection.   This ensures the proper and efficient

j                                                   ....

              operation of the system.  Compliance with the Sewer Use



I              Ordinance is the only remaining user responsibility.


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 2.
ewer Authority Re
      Easement, acquisition  is  the  responsibility of the




 Sewer Authority, either directly,  or  through contract  with




 a right-of way agent.  In either case,  the hydraulic limits




 of the system must be understood prior to making any




 changes that may be requested  by the  property owner.   For




 this reason, some Authorities  employ  the services  of the




 design engineer for this task.




      The actual vacuum valve  is not  installed until the




 customer is ready to connect to the valve pit setting.   It




 is common for the the contractor to install the valve




 pit/sump,  including all of  the necessary piping, during




 system construction  The valve is  then supplied to the




Authority for their installation at a later date.  In  this




 manner,  the Authority can systematically install the valves




as each customer requests connection.   Each valve  is "timed-




out" with the time setting  being recorded for future




reference.   The time setting on the first few valves are




 typically changed once or twice after start-up as  system




hydraulics continually changes until  all customers are




connected.   All valves are  then finetuned to operate as  a




complete system.   ....

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             ADD DISCUSSION ON VIDEO TARING-SEE BOWNES SECTION!!
ff-

             I I ] I j I I t I I I I I I I I j I | J I I I I  | ! II MM

             ................................ '
                   Once all customers are connected, the Authority is

             focused on providing reliable, efficient service to their

             customers.   To achieve this,  the operating personnel must

             be capable,  dependable,  and knowledgeable.   Of utmost

             importance is  attitude.   An operator that does not believe

             in the system  will ultimately cause the system to operate

             below  its  potential,  in  terms of reliability and costs.

             Conversely,  one with a good attitude uses creativity to get

             more out of  the  system than was originally planned.

                   To operate  any system at a high level of efficiency

             requires a Sewer  Use  Ordinance.   This document sets

             consistent rules  for  all  users to follow.   Included are

             material specifications for the building sewer,  minimum

             slope requirements,  and vent locations.  Of extreme

             importance to the Authority is to limit use of the vacuum

             sewer to sanitary wastes  only,  as extraneous water will

             cause operational problems.

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       An  active  program  far  the  identification  of

 extraneous  Mater sources should  be  developed.'  This  may

 include smoke  testing and dye  testing.   To identify  and

 quantify  sources of extraneous water,  the  Authority  can
                                                      w

 take advantage of a integral feature  of a  vacuum system;

 the cycle counter.  This device,  when connected to the

 valve, will record the number  of times the valve opens in  a

 given  period.  Knowing that  each cycle is  approximately 11


 gallons,  the Authority can estimate,  based on water

 consumption records, the number  of  cycles  expected over

 that period.   A  count much in  excess  of the expected may be

 a sign of extraneous water.  To  quantify the amount,  the

number of cycles is multiplied by 11  gallons and compared

 to the water consumption.  Listening  to the auxiliary vent

for sounds of  running water  when  no flushing activity is

 taking place may also provj.de  clues for sources of

extraneous water.

      The Authority also is  responsible for future

extensions of  the system.  This  includes proper planning.

design, and construction of  such extensions.  Finally.

future connections to the existing  system  are made by the

Authority in accordance  with the provisions of  the Sewer

Use Ordinance.

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 r
              3.
       Qther Entities
F
       During the planning,  design and construction of sewer



 systems,  there are many different entities involved.   Two




 of these are regulatory agencies and the engineer.   It is




 during these times that many decisions are made and details




 finalized-   Often,  these entities view the start-up of a




 system as their final involvement.   While this attitude is




 understandable,  it is not acceptable.   Continuing




 involvement is needed to help a viable,  cost-effective




 technology grow.




       The engineer should spend a significant amount of




 time during the start-up of the system.   Tests should be




 run,  and problems simulated,  to eee if the system is




 operating as designed.   Periodically,  the operating records




 should be analyzed for budget sufficiency purposes.




 Problems and the'ir solutions should be recorded.   In short,




 the engineer should use the operating experience of the




 system to help develop improvements in future designs.




       Likewise,  regulatory  agencies should follow up on the




 operation of a new system.   Information on problems,



 including the cause and the remedies,  should be gathered.




 Cost  data should be obtained.   This type of information can




 then  be used for future projects.




       It  is  this present lack of information that causes




 many  engineers and regulatory agencies to shy away from a




new technology.   It has become easier to be conservative,



and hence' unduly critical,  rather than to learn the details




of a new  technology,  no matter how  costeffective.




       "--"-'-.           7

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 r
                                 CHAPTER   5
                                 SECTION   2
                                   DESIGN EXAMPLE
                                   VACUUM  SEWERS
r
                                                    Reprinted from AIRVAC
                                                    Design Manual

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                             Chapter  7
Design Example
Consider the vacuum sewer layout shown In figure 28. The location of the collection
station, sewers and A*tJvfe*  valves have been selected in accordance with the
              ^S-SKJ7~
requirements oVChapter a which are restated below:
    Locate sewers to:   Minimize lift
                      Minimize length
                      Where possible to equalize flows on each sewer.

Loje^eAJFWgx*alee4o'sfe^                                         
For the design example each 4QFrvMU& valve Is assumed to serve two homes and that the
peak flow per home is 0.64 gpm or 1.28 gpmlfflM&F* valve Installation.

To efficiently serve the area shown inSTgure28l four main sewers will be required. Each of
these main sewers is connected directly to the vacuum tank at the collection station.
Sewers are not joined together into a bus main outside the station.

Division valves have been located to  isolate areas of the sewer network for trouble-
shooting purposes.
        /^~~~-
Prof lies (F/ff. 29 and sqAtave been prepared for main #1 and Its two branch sewers. The
profiles for mains 2,3, and 4 will be similar.
Profiles for main #1 follow the principals stated In Chapter 5 and
    Maximum length of 4" sewer  2,800 ft.
    80% pipe diameter drop or 0.2% fall between lifts; whichever is greater.
    Where the ground profile falls greater than 0.2% in the flow direction, the sewer pro-
    file follows the ground.
                                      55

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M DIVISION VALVE
                                                URE a - DESIGN EXAMPLE
                                            1<

-------
 Location otXwV^p* valves and  branch sewer connections follow the principals of
 Chaptoro 6 and 9.  SeCT^o*->  O
             -o^_
 Location of U/tpMKP- valves and branch sewer connections and access points follow the
 principals of Qbf$tg}*5-aQiLi  "5
 Prepare total line loss calculations from the sewer profiles {Fig. 31).
Procedure. Commence at point A. Calculate losses to point D. Calculate losses and flows
from C to D. Determine the line with the greatest loss and carry forward, i.e. if the total line
loss from A to D is greater than the total line loss from C to D, carry forward A to D. DO
NOT ADD TOTAL LINE LOSSES WHERE BRANCH SEWERS JOIN THE MAIN. If the total
line loss from C to D is greater than A to D then C-D-F becomes the main sewer for total
line loss calculation purposes. Total the sewage flow from A-D and C-D. Calculate the
total line losses from D to F and continue towards the collection station.
See figure 31 for calculation of line losses in main #1. Remember the static loss of profile
                                                                             A
changes of 12" or under is counted as half the change. (12" change 6" loss, etc.)
Using the same method total line loss, flows and pipe sizes can be calculated for mains 2,
3 and 4. Flows,- pipe sizes and lengths for these mains have been estimated to enable
figures 32 and 33 to be completed.

When all machinery calculations are complete, consult manufacturers literature to
select suitable standard size pumps and tanks. Vacuum and sewage pump sizes should
be selected to allow for additional house connections to be made without overloading.
                                  JU
                                                     fleu,

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TOTALS
                                                                                                                                    a
                                                                                                                                    i
                                                                                                                                    e
                                                                                                                                    it
                                                             61

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 r
 L
f
 L.
                                     Vacuum Sewerage System
PROJECT.
           DESIGN EXAMPLE
PROJECT NUMBER.
       STATION NUMBER.
                                                   DATE.
                                                                    MARCH 1986
LINE

1
2
3
4
TOTALS
CROSSOVERS
41 * r
TOTAL
3" PIPE
3"
PIPE



1640
1640
4"
PIPE

4640
3825
3750
5850
18,265
6"
PIPE



8"
PIPE



PEAK
FLOW

25.6
23.04
21.76
34.56
104.96
NUMBER
CROSS-
OVERS
*
10
9
8
14
41
NUMBER
AIRVAC'
VALVES

20
18
17
27
82
* ASSUME 50% OF VALVES REQUIRE CROSSOVERS.
      VOLUME OF PIPEWORK (BASED ON SDR 21 PVC PIPE)
      Vp m 7.5 (.0547 x LENGTH 3" + .0904 x LENGTH 4" + .1959 x LENGTH 6" + .3321 x LENGTH 8")
      Vp m 7.5 (       90 +     1651    +    -     +         )
      Vp * 7.5 (1741) GALLONS
      Vp = 13,057   GALLONS
      *A Vp = 8705  GALLONS

                                            FIGURE 32
n
                                              62

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'
    Project
            DESIGN EXAMPLE
r
P




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Station Number.
    (Flow
Average Flow
Minimum Flow
                               Qmax
                               Qa =
                               Qmin
    Vacuum Pump Capacity Required
    (Insert A in Calculation For Qvp:)
Longest Line Length
0-3000'
3001'- 7000'
7001 '-10,000'
10,001'  12,000
Over 12,001'
A
5
6
7
B
10
    Discharge Pump Capacity
    Collection Tank Operating Volume
    (for 15 mln. cycle at Qmln)
    Vo = 15 QmJnJQdp  Qmin)
            Qdp
    Total Volume Collection Tank
    NOTE: MINIMUM Vet        =400 gal.
    Vacuum Reservoir/Moisture
    Removal Tank
    (Recommended Volume Vrt = 400 gal.)
    System Pump Down Time for Operating
    Range of 16" to 20" Hg Vacuum
    t should be less than 6 mins. If over,
    increase Qvp to give *t* under 6 mins. If
    't' is under 1 mln. Increase Vrt.
    Total Dynamic Head On Discharge Pump
                                                              Project Number	
                                                                Date	MARCH 1986
Vacuum Sewerage System
         Qmax
       Peak Factor
                                                                                     105
                                                                                       .g.p.m.
    =   Qmax
          Qa
          2
Qvp =  Ax Qmax
       7.5 gal/ft
        5x105
                                                                                  30
                                                                                  15
                                                                       7.5 gal/ft
                                                                                       .g.p.m.
                                                                                        c.f.m.
                                                                                        c.f.m.
                          Qvp =
                          Qdp =
                          Vo =
                          Vo =
                          Vo =
                          Vet =

                          Vrt =
                                                                                70
                                                                                        c.f.m.
                                                                     Qmax    =   105    g.p.m.
                                                                    1.84 Qmax for 3.5 Peak Factor
                                                                    1.64 Qmax for 4.0 Peak Factor
                                                                     3V6
                                                                                 580
                                                                             400
                                                                                          gal.
                                                    t =(0.045 cfm-min.) (2/3 Vo + (Vct-Vo) 4- VrQoai.
                                                               gal.           Qvp cfm
                                                    t m Q.04S t 8705  4. | 580  .  193  \ +  400 \
                                                                            70
                                                                      6.10*
                                                                                       .mins.
                                              Tdh
Tdh = Head Due to Vacuum + Static Head + Friction Loss
Tdh =      23      +	+	ft.
Tdh m	ft.
NPSH Calculation
    = ha + Vmax  =	'	+	
    NPSHA
    NPSHA
         navt + hs - hf - hvpa
         	+	
                                          	ft.
                                           RQURE 83
                                             63
                                                                 IN THIS EXAMPLE TO GIVE
                                                                 A T UNDER 6 MINS.
                                                                 Qvp SHOULD BE INCREAS

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