United States Environmental A"enc

Protection

Office Of Water (4204)

EPA 832-R-93-008 Jul !993

Su#surface $lo% &onstructed Wetlands $or WasteWater 'reatment

Printed on Recycled Paper

Acknowledgements

ACKNOWLEDGE ENT!

"# !he"wood C# $eed% &#E#% o' En()"onment*l Eng)nee")ng Cons+lt*nts w*s the *ny othe"s *lso cont")-+ted to )ts ,")nc),*l *+tho" *nd ed)to" o' th)s doc+ment# de(elo,ment# .nst"+ment*l )n ,"o()d)ng )n,+t )nto th)s doc+ment we"e the wo"ksho, ,*"t)c),*nts who met )n New O"le*ns )n !e,tem-e"% /002% *nd ,"o()ded techn)c*l *nd ed)to")*l comments# !,ec)*l th*nks to $o-e"t E# Lee% Ch)e'% +n)c),*l Technology 1"*nch% *nd $o-e"t 1*st)*n% Wo"k Ass)gnment *n*ge" 2o' the 3#!# E&A O'')ce o' W*stew*te" En'o"cement *nd Com,l)*nce% 'o" the)" )n,+t *nd s+,,o"t *nd to Eng)nee")ng2!c)ence% .nc# wh)ch ,"o()ded m*n*gement *nd ,"od+ct)on s+,,o"t d+")ng th)s e''o"t#

E4ec+t)(e !+mm*"y

E(E&U')*E SU++AR,

.nte"est )n% *nd the +t)l)5*t)on o'% const"+cted wetl*nds 'o" t"e*tment o' * (*")ety o' w*stew*te"s h*s g"own "*,)dly s)nce the m)d /060s# 7owe(e"% * l*ck o' consens+s h*s "es+lted )n the +se o' d)''e"ent% *nd o'ten con'l)ct)ng% c")te")* *nd The"e'o"e * -ette" +nde"st*nd)ng o' the g+)d*nce 'o" the des)gn o' these systems# )nte"n*l "eno(*t)(e ,"ocesses )n these systems w*s essent)*l 'o" the '+t+"e *,,l)c*t)on 8o' th)s ,"om)s)ng technology% *nd to ens+"e "el)*-le *nd cost2e''ect)(e des)gn ,"oced+"es# A consens+s on the "e,o"t contents w*s "e*ched ()* se(e"*l "e()ew cycles -y *n )nte"n*t)on*lly "ecogn)5ed ,*nel o' e4,e"ts *nd ()* d)sc+ss)ons *t * two2 d*y wo"ksho, )n !e,tem-e" /002# Two ty,es o' const"+cted wetl*nds *"e )n common +se9 the ')"st ty,e% the '"ee w*te" s+"'*ce (:W!) wetl*nd% e4,oses the w*te" s+"'*ce )n the system to the *tmos,he"e# The second ty,e% the s+-s+"'*ce 'low (!:) wetl*nd% m*)nt*)ns the w*te" le(el -elow the s+"'*ce o' g"*(el o" othe" med)* ,l*ced )n the wetl*nd -ed# Th)s "e,o"t )s conce"ned w)th the !: wetl*nd ty,e# Th)s "e,o"t (e")')es th*t !: const"+cted wetl*nds c*n -e * "el)*-le and cost2 These h*(e )ncl+ded# e''ect)(e t"e*tment method 'o" * (*")ety o' w*stew*te"s# domest)c% m+n)c),*l% *nd )nd+st")*l w*stew*te"s *s well *s l*nd')ll le*ch*tes# A,,l)c*t)ons "*nge '"om s)ngle '*m)ly dwell)ngs% ,*"ks% schools% *nd othe" ,+-l)c '*c)l)t)es to m+n)c),*l)t)es *nd )nd+st")es# .t c*n -e * low2cost% low2ene"gy ,"ocess "e;+)")ng m)n)m*l o,e"*t)on*l *ttent)on# As s+ch the conce,t )s ,*"t)c+l*"ly well s+)ted 'o" sm*ll to mode"*te s)5ed '*c)l)t)es whe"e s+)t*-le l*nd m*y -e *(*)l*-le *t * "e*son*-le cost# !)gn)')c*nt *d(*nt*ges )ncl+de l*ck o' odo"s% l*ck o' mos;+)toes *nd othe" )nsect (ecto"s% *nd m)n)m*l ")sk o' ,+-l)c e4,os+"e *nd cont*ct w)th the w*te" )n the system# The ,"ocess c*n "emo(e 1OD *nd s+s,ended sol)ds to (e"y low concent"*t)ons *nd ,"od+ce the e;+)(*lent o' te"t)*"y e''l+ent# .nte")m des)gn g+)del)nes 'o" 1OD "emo(*l *"e ,"o()ded )n the "e,o"t# N)t"ogen "emo(*l to (e"y low le(els )s ,oss)-le )' s+'')c)ent detent)on t)me *nd o4ygen to s+,,o"t the necess*"y n)t")')c*t)on "e*ct)ons *"e ,"esent# *ny o' the e*"ly systems we"e de')c)ent )n -oth "es,ects# Co""ect)(e *ct)on )s ,oss)-le% *nd the "e,o"t ,"esents tent*t)(e methods 'o" *,,"o,")*te des)gn# A l)m)ted d*t* -*se s+,,o"ts the c*,*-)l)ty o' the !: wetl*nd ,"ocess 'o" e''ect)(e 7owe(e"% the ,"ocess h*s l)m)ted "emo(*l o' met*ls *nd othe" ,")o")ty ,oll+t*nts# c*,*c)ty 'o" "emo(*l o' ,hos,ho"+s *s ,"esently conce)(ed% *nd s+,,lement*l t"e*tment m*y -e necess*"y# A one2 o" two2log "ed+ct)on )n 'ec*l col)'o"ms c*n -e
< <

ii

E4ec+t)(e !+mm*"y

"el)*-ly *ch)e(ed w)th th)s ,"ocess% lowe" le(els m*y "e;+)"e ,ost d)s)n'ect)on# .n *dd)t)on to des)gn g+)del)nes% the "e,o"t ,"o()des *n *ssessment o' conce,t *,,l)c*-)l)ty *nd the "ese*"ch needs 'o" * -ette" +nde"st*nd)ng o' the ,"ocess#

)))

&"e'*ce

PRE$A&E

Th)s "e,o"t w*s s,onso"ed -y the 3#!# E&A O'')ce o' W*stew*te" En'o"cement *nd Com,l)*nce +nde" the d)"ect)on o' "# $o-e"t K# 1*st)*n% *nd "# $o-e"t E# Lee% o' the +n)c),*l Technology 1"*nch# .t )s the )ntent o' th)s "e,o"t to ,"esent c+""ent (/00=) )n'o"m*t)on *nd g+)d*nce on des)gn% const"+ct)on% ,e"'o"m*nce% o,e"*t)on *nd m*)nten*nce o' s+-s+"'*ce 'low const"+cted wetl*nds +sed 'o" t"e*tment 8o' domest)c *nd m+n)c),*l w*stew*te"s# !+-s+"'*ce 'low const"+cted wetl*nds *"e )n "el*t)(ely common +se )n E+"o,e% A+st"*l)*% *nd )n * n+m-e" o' st*tes )n the 3n)ted !t*tes# 7owe(e"% the"e h*s -een no *,,*"ent consens+s on des)gn ,"oced+"es o" ,e"'o"m*nce e4,ect*t)ons# A two2 ste, ,"oced+"e w*s +sed 'o" the ,"e,*"*t)on o' th)s "e,o"t to de(elo, * consens+s *mong knowledge*-le e4,e"ts# The ')"st ste, w*s to s+-m)t * d"*'t "e,o"t ,"e,*"ed -y "# !he"wood $eed% E#E#C#% to selected e4,e"ts 'o" the)" det*)led "e()ew# These )nd)()d+*ls )ncl+ded9 "# Don*ld 1"own% 3#!# E&A $$EL> D"# Denn)s Geo"ge% Tennessee Tech 3n)(e"s)ty> "# )ch*el Ogden% !o+thwest Wetl*nds G"o+,9 D"# $)ch*"d Ge"s-e"g% !*n D)ego !t*te 3n)(e"s)ty> "# $on*ld C")tes% Nolte ? Assoc)*tes> D"# $o-e"t Kn)ght% C72 7)ll> D"# Geo"ge Tcho-*noglo+s% 3n)(e"s)ty o' C*l)'o"n)*2D*()s> "# )ch*el 7)nes% Tennessee @*lley A+tho")ty> D"# :"*nk !*+nde"s% cC+lley% :")ck ? G)lm*n% .nc#> *nd D"# &ete" Aenssen% Ao"d'o"sk% No"w*y# The second ste, w*s *ccom,l)shed *t * two2d*y wo"ksho, held )n New O"le*ns%#2LA on !e,tem-e" 24 *nd 2<% /002# &*"t)c),*nts )n th*t meet)ng )ncl+ded )n()ted e4,e"ts% "e,"esent*t)(es '"om 3! E&A $eg)on @.% st*te *nd loc*l o'')c)*ls% *nd loc*l des)gn ')"ms w)th e4,e")ence w)th th)s technology# These ,*"t)c),*nts *"e l)sted )n A,,end)4 A o' th)s "e,o"t# The wo"ksho, commenced w)th * det*)led ,"esent*t)on Th)s w*s 'ollowed -y )ntens)(e d)sc+ss)on -y o' the contents o' the d"*'t "e,o"t# ,*"t)c),*nts on *ll o' the m*Bo" to,)cs o' conce"n# Add)t)on*l t)me w*s t*ken *t the meet)ng to )dent)'y "ese*"ch needs 'o" '+"the" o,t)m)5*t)on o' th)s technology# A "e()sed (e"s)on o' the te4t w*s then c)"c+l*ted to *ll ,*"t)c),*nts *nd ,"e()o+s "e()ewe"s 'o" the)" comments# The ,"e,*"*t)on o' th)s ')n*l "e,o"t cons)de"s *ll o' the comments *nd s+ggest)ons "ece)(ed '"om *ll so+"ces# As * "es+lt% th)s "e,o"t "e,"esents * consens+s *mong the e4,e"ts ,*"t)c),*t)ng )n th)s e''o"t on des)gn% const"+ct)on% *nd o,e"*t)on C+""ent *nd '+t+"e *nd m*)nten*nce o' s+-s+"'*ce 'low const"+cted wetl*nds#

iv

&"e'*ce

"ese*"ch w)ll +ndo+-tedly )m,"o(e +nde"st*nd)ng o' the -*s)c conce,ts )n(ol(ed *nd The des)gn ,"oced+"es *nd "el*ted le*d to mo"e so,h)st)c*ted des)gn models# g+)d*nce )n th)s "e,o"t *"e the"e'o"e cons)de"ed to -e (*l)d% -+t s+-Bect to '+"the" )m,"o(ement#

T*-le o' Contents

TA1LE O: CONTENT!

ACKNOWLEDGE ENT! ################################################################## ###################################### ) ECEC3T.@E !3 &$E:ACE C7A&TE$ / C7A&TE$ 2 C7A&TE$ = A$D # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # )) )( /2/ 22/

################################################ .NT$OD3CT.ON 1ACKG$O3ND ############################## ############################### E@AL3AT.ON! # ########### ########### ########### ########### ######### # # # # # # # # # # # # # # # # # # # =2/
#####################

&E$:O$ ANCE ##### ###### T!! $emo(*l N)t"ogen $emo(*l ### &hos,ho"+s $emo(*l # :ec*l Col)'o"m $emo(*l

1 O D< $emo(*l

##################### #################### #################### ####################

=22 =26 =2/0 =2/E =2/F 42/

C7A&TE$ 4

DE!.GN CON!.DE$AT.ON! # # # # # # # # # # # # # # # # # # # # # # # #####################

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C7A&TE$ < CON!T$3CT.ON DETA.L! # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # <22 costs ########################### ON2!.TE !: WETLAND !D!TE ! C7A&TE$ E ##################### Lo+)s)*n* ethod ######################## T@A ethod ####### &l+g :low odel 'o" On2!)te !ystems #### #### #### #### # # # # ################ ############## ############### ###############

E2/ E2/ E2= E2E

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T*-le o' Contents

OT7E$ &OTENT.AL C7A&TE$ F ######## !to"mw*te" !ystems ## # # # # # # # # # L*nd')ll Le*ch*tes ##### ######### )ne D"*)n*ge # ######### Ag")c+lt+"*l $+no''

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F2/ F2/ F22 F22 F22 62/ 62/ 622 622

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APPE-.)(
A 2 L)st o' ,*"t)c),*nts )n New O"le*ns wo"ksho,# 1 2 &"ocess det*)ls 'o" systems l)sted )n T*-le 2#

vii

T*-le o' Contents

/)S' O$ 'A0/ES

T*-le /# T*-le 2# T*-le =# T*-le 4# T*-le <# T*-le E# T*-le F#

7)sto")c*l Des)gn A,,"o*ches% E+"o,e*n *nd 3#!# !o+"ces # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # D*t* !o+"ces 'o" &e"'o"m*nce E(*l+*t)on # # # # # # # # # # # # # # # # # # Com,*")son o' :)"st O"de" &l+g ############################ :low $*te Const*nts Ammon)* $emo(*l )n !: Wetl*nds #################### Ty,)c*l ed)* Ch*"*cte")st)cs 'o" !: Wetl*nds # # # # # # # # # # # # # &e"'o"m*nce o' @eget*ted *nd 3n(eget*ted !: ################################ Wetl*nd 1eds &otent)*l O4ygen :"om @eget*t)on *t !*ntee% CA # # # # # # # # # #

224 =2/ =26 =2/= 42E 42/2 42/<

/)S' O$ $)1URES

:)g+"e /# :)g+"e 2# :)g+"e =# :)g+"e 4# :)g+"e <# :)g+"e E# :)g+"e F# :)g+"e 6# :)g+"e 0# :)g+"e /0# :)g+"e //# :)g+"e /2# :)g+"e /=# :)g+"e /4# :)g+"e /<#

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1 O D< .n,+t @e"s+s O+t,+t

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!+s,ended !ol)ds% .n,+t @e"s+s O+t,+t # # # # # # # # # # # # # # # # # # !+s,ended !ol)ds $emo(*l @e"s+s 7$T # # # # # # # # # # # # # # # # # # ###### !+s,ended !ol)ds $emo(*l @e"s+s !ystem As,ect $*t)o ######################## Ammon)* .n,+t @e"s+s O+t,+t ################## ### Ammon)* $emo(*l @e"s+s 7$T ################ TKN *ss Lo*d)ng @e"s+s *ss $emo(*l ############ E''l+ent Ammon)* @e"s+s TKN *ss Lo*d)ng ############### ##### &hos,ho"+s .n,+t @e"s+s O+t,+t # # # # ############# ## L)th)+m T"*ce" !t+dy% C*"()lle% LA ############ Cost D)st")-+t)on 'o" !: Const"+cted Wetl*nds ####### Act+*l Cost D)st")-+t)on 'o" *n !: !ystem )n Lo+)s)*n*

=22 =2= =24 =2< =26 =20 =20 =2// =2/2 =2/4 =2/< =2/E 42/0 <2= <24

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L)st o' A--"e()*t)ons

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L)st o' A--"e()*t)ons

N n N 7= N&DE! 0 2H m H d OL &#E# &E &@C I $$EL !: TKN T!! T@A 3#!# 3#!# E&A W W&C:
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&2AP'ER ! )-'RO.U&')O-

Th)s "e,o"t desc")-es the des)gn% const"+ct)on *nd ,e"'o"m*nce o' s+-s+"'*ce 'low const"+cted wetl*nds *s +sed )n the 3n)ted !t*tes 'o" w*stew*te" t"e*tment# 3t)l)5*t)on o' th)s technology h*s g"own (e"y "*,)dly )n the ,*st ')(e ye*"s (/06620=)% *nd )t )s cle*" '"om the d)sc+ss)on )n the ne4t sect)on o' the "e,o"t th*t the"e h*s -een no gene"*l consens+s on des)gn o' these systems o" the)" ,e"'o"m*nce e4,ect*t)ons# .n "ecogn)t)on o' th*t s)t+*t)on% (*")o+s o'')ces w)th)n 3#!# E&A% *s well *s othe" *genc)es *nd g"o+,s% h*(e s,onso"ed se(e"*l e''o"ts to -ette" +nde"st*nd wetl*nd systems *nd the)" c*,*-)l)t)es *nd l)m)t*t)ons 'o" w*stew*te" t"e*tment# These e''o"ts h*(e )ncl+ded9 * det*)led% m+lt)2ye*" mon)to")ng ,"og"*m *t se(e"*l const"+cted wetl*nds )n 2Kent+cky (s,onso"ed -y E&A he*d;+*"te"s% the N*t)on*l !m*ll :lows Cle*")ngho+se% E&A $eg)on .@% *nd T@A)> *n )n(ento"y o' *ll const"+cted wetl*nds +sed 'o" w*stew*te" t"e*tment )n the 3#!# (s,onso"ed -y E&A $$EL)> s)te ()s)ts w)th e(*l+*t)ons *nd "e,o"ts *t selected o,e"*t)ng s+-s+"'*ce 'low wetl*nds )n the 3#!# (s,onso"ed -y E&A $$EL)> * -")e' ,e"'o"m*nce e(*l+*t)on *t th"ee s+-s+"'*ce 'low systems )n Lo+)s)*n* (s,onso"ed -y E&A 7e*d;+*"te"s)> det*)led ,e"'o"m*nce mon)to")ng *nd e(*l+*t)on *t two s+-s+"'*ce 'low systems% *lso )n Lo+)s)*n* (s,onso"ed -y E&A $$EL)> c"e*t)on o' * det*)led d*t* -*se co(e")ng des)gn% o,e"*t)ng *nd ,e"'o"m*nce d*t* 'o" n*t+"*l *nd const"+cted wetl*nd systems t"e*t)ng m+n)c),*l *nd )nd+st")*l w*stew*te" *nd sto"m w*te" "+no'' )n the 3#!# (s,onso"ed -y E&A Co"(*ll)s)> *nd se(e"*l wo"ksho,s *nd sem)n*"s s,onso"ed -y E&A $eg)on @.# All o' these so+"ces we"e +t)l)5ed )n the ,"e,*"*t)on o' th)s "e,o"t *nd the The 'oc+s o' th)s "e,o"t )s the d)sc+ss)on *nd e(*l+*t)ons wh)ch *"eG )ncl+ded# s+-s+"'*ce 'low ty,e wetl*nd# .n'o"m*t)on on othe" ty,es o' wetl*nd systems h*s h*s -een )ncl+ded 'o" com,*"*t)(e ,+",oses#

l2l

Ch*,te" 2

&2AP'ER 2 0A&31ROU-. Wetl*nds *"e de')ned *s l*nd whe"e the w*te" s+"'*ce )s ne*" the g"o+nd s+"'*ce l+ng eno+gh e*ch ye*" to m*)nt*)n s*t+"*ted so)l cond)t)ons% *long w)th the *"shes% -ogs% *nd sw*m,s *"e *ll e4*m,les o' n*t+"*lly "el*ted (eget*t)on# A Jconst"+cted wetl*ndK )s de')ned *s * wetl*nd s,ec)')c*lly occ+"")ng wetl*nds# const"+cted 'o" the ,+",ose o' ,oll+t)on cont"ol *nd w*ste m*n*gement% *t * loc*t)on The"e *"e two -*s)c ty,es o' const"+cted othe" th*n e4)st)ng n*t+"*l wetl*nds# wetl*nds% the '"ee w*te" s+"'*ce wetl*nd *nd the s+-s+"'*ce 'low wetl*nd# 1oth ty,es +t)l)5e eme"gent *;+*t)c (eget*t)on *nd *"e s)m)l*" )n *,,e*"*nce to * m*"sh# The '"ee w*te" s+"'*ce (:W!) wetl*nd ty,)c*lly cons)sts o' * -*s)n o" ch*nnels w)th some ty,e o' -*"")e" to ,"e(ent see,*ge% so)l to s+,,o"t the "oots o' the eme"gent (eget*t)on% *nd w*te" *t * "el*t)(ely sh*llow de,th 'low)ng th"o+gh the system# The w*te" s+"'*ce )s e4,osed to the *tmos,he"e% *nd the )ntended 'low ,*th th"o+gh the system )s ho")5ont*l# The s+-s+"'*ce 'low (!:) wetl*nd *lso cons)sts o' * -*s)n o" ch*nnel w)th * -*"")e" to ,"e(ent see,*ge% -+t the -ed cont*)ns * s+)t*-le de,th o' ,o"o+s med)*# $ock o" g"*(el *"e the most commonly +sed med)* ty,es )n the 3#!# The med)* *lso s+,,o"t the "oot st"+ct+"e o' the eme"gent (eget*t)on# The des)gn o' these systems *ss+mes th*t the w*te" le(el )n the -ed w)ll "em*)n -elow the to, o' the "ock o" g"*(el med)*# The 'low ,*th th"o+gh the o,e"*t)on*l systems )n the 3#!# )s ho")5ont*l# '4e S$ t 5e of %etland is t4ou"4t to 4ave several advanta"es over t4e $WS ty,e# .' the w*te" s+"'*ce )s m*)nt*)ned -elow the med)* s+"'*ce the"e )s l)ttle ")sk o' odo"s% odo"s% e4,os+"e% o" )nsect (ecto"s# .n *dd)t)on% )t )s -el)e(ed th*t the med)* ,"o()des g"e*te" *(*)l*-le s+"'*ce *"e* 'o" t"e*tment th*n the :W! conce,t so the t"e*tment "es,onses m*y -e '*ste" 'o" the !: ty,e% wh)ch the"e'o"e c*n -e sm*lle" )n *"e* th*n * :W! system des)gned 'o" the s*me w*stew*te" cond)t)ons# s+-s+"'*ce# ,os)t)on o' the w*te" *nd the *cc+m+l*ted ,l*nt de-")s on the s+"'*ce o' the !: -ed o''e" g"e*te" the"m*l ,"otect)on )n cold cl)m*tes th*n the :W! ty,e# !+-s+"'*ce 'low const"+cted wetl*nds ')"st eme"ged *s * w*stew*te" t"e*tment technology )n Weste"n E+"o,e -*sed on "ese*"ch -y !e)del (/) commenc)ng )n the /0E0s% *nd -y K)ck+th (2) )n the l*te /0F0s *nd e*"ly /060s# E*"ly de(elo,ment*l wo"k )n the 3n)ted !t*tes commenced )n the e*"ly /060s w)th the "ese*"ch o' Wol(e"ton% et *l# (=) *nd Ge"s-e"g et *l# (4)#

The

22l

Ch*,te" 2 The !: conce,t de(elo,ed -y !e)del )ncl+ded * se")es o' -eds com,osed o' s*nd o" g"*(el s+,,o"t)ng eme"gent *;+*t)c (eget*t)on s+ch *s c*tt*)ls (Typha), -+l"+sh (Scirpus), *nd "eeds (Phragmites), w)th Phragmites -e)ng the most commonly +sed# .n the m*Bo")ty o' c*ses% the 'low ,*th w*s (e"t)c*l th"o+gh e*ch cell to *n +nde"d"*)n *nd then onto the ne4t cell# E4cellent ,e"'o"m*nce 'o" "emo(*l o' 1OD < T!!% n)t"ogen% ,hos,ho"+s% *nd mo"e com,le4 o"g*n)cs w*s cl*)med# &)lot st+d)es o' the conce,t )n the 3n)ted !t*tes we"e m*"g)n*lly s+ccess'+l% *nd )t h*s not -een +t)l)5ed )n "ecent ye*"s )n th)s co+nt"y# K)ck+th ,"o,osed the +se o' cohes)(e so)ls )nste*d o' s*nd o" g"*(el> the (eget*t)on o' ,"e'e"ence w*s Phragmites *nd the des)gn 'low ,*th w*s ho")5ont*l th"o+gh the so)l med)*# K)ck+thGs theo"y s+ggested th*t the g"owth% de(elo,ment *nd de*th o' the ,l*nt "oots *nd "h)5omes wo+ld o,en +, 'low ch*nnels% to * de,th o' *-o+t 0#E m (2 't) )n the cohes)(e so)l% so th*t the hyd"*+l)c cond+ct)()ty o' * cl*y2l)ke so)l wo+ld g"*d+*lly -e con(e"ted to the e;+)(*lent o' * s*ndy so)l# Th)s wo+ld ,e"m)t 'low th"o+gh the med)* *t "e*son*-le "*tes *nd wo+ld *lso t*ke *d(*nt*ge o' the *dso",t)(e c*,*c)ty o' the so)l 'o" ,hos,ho"+s *nd othe" m*te")*ls# @e"y e''ect)(e "emo(*l o' 1OD < T!!% n)t"ogen% ,hos,ho"+s% *nd mo"e com,le4 o"g*n)cs w*s cl*)med# As * "es+lt% -y /000 *-o+t <00 o' these J"eed -edK o" J"oot 5oneK systems h*d -een const"+cted )n Ge"m*ny% Denm*"k% A+st")*% *nd !w)t5e"l*nd# The ty,es o' systems )n o,e"*t)on )ncl+de on2s)te s)ngle '*m)ly +n)ts *s well *s l*"ge" systems *ny o' the 2e*"ly systems we"e t"e*t)ng m+n)c),*l *nd )nd+st")*l w*stew*te"s# 2 des)gned (<) w)th * c")te")on o' 2#2 m o' -ed s+"'*ce *"e* ,e" ,o,+l*t)on e;+)(*lent (&E)# A &E )n E+"o,e*n te"ms )s e;+)(*lent to the o"g*n)c lo*d)ng '"om one ,e"son% o" *,,"o4)m*tely 0#04 kgHd 1OD < )n ty,)c*l ,")m*"y e''l+ent# Th*t )s e;+*l to * s+"'*ce o"g*n)c lo*d)ng o' *-o+t /60 kgHh*Hd (/E2 .-H*cHd)# The mo"e "ecently 2 const"+cted systems )n E+"o,e (/<) h*(e -een des)gned 'o" < to /0 m H&E (40 2 60 2 = kgHh*Hd)# The hyd"*+l)c lo*d)ng *t < m H&E (*t *n *ss+med 0#2 m HdH&E) wo+ld -e *-o+t 4 cmHd (/#E )nHd)% wh)ch% )n * commonly +sed te"m )n the 3#!#% )s e;+)(*lent to 2= *c"esHmgd o' des)gn 'low% *nd wo+ld ,"o()de * hyd"*+l)c "es)dence t)me (7$T) o' *-o+t s)4 d*ys# :o" com,*")son% :W! wetl*nds )n E+"o,e *"e ty,)c*lly des)gned *t /0% 2 m H&E% wh)ch "es+lts )n * s+"'*ce *"e* *-o+t tw)ce th*t "e;+)"ed 'o" the !: ty,e (=0)# Commenc)ng )n /06<% * n+m-e" o' J"eed -edK systems we"e const"+cted )n G"e*t 1")t*)n -*sed on K)ck+thGs conce,ts% -+t )n m*ny c*ses g"*(el w*s +sed *s the -ed med)* "*the" th*n cohes)(e so)l (<) d+e to conce"ns "eg*"d)ng so)l hyd"*+l)c *ny o' these -eds we"e -+)lt w)th * slo,)ng -ottom (0#< to /L) *nd cond+ct)()ty# * 'l*t s+"'*ce# The ,+",ose o' the slo,)ng -ottom w*s to ,"o()de s+'')c)ent hyd"*+l)c g"*d)ent to ens+"e s+-s+"'*ce 'low )n the -ed# The 'l*t +,,e" s+"'*ce wo+ld *llow tem,o"*"y 'lood)ng *s * weed cont"ol me*s+"e to k)ll +ndes)"*-le ,l*nts# !ome o'

222

Ch*,te" 2

these systems *lso h*d *n *dB+st*-le o+tlet wh)ch ,e"m)tted e*sy m*)nten*nce o' the des)"ed w*te" le(el )n the -ed (/0)# Wol(e"tonGs wo"k )n Lo+)s)*n* -eg*n w)th e4,e")ment*l -ench sc*le t"*ys )n * g"eenho+se cont*)n)ng "ock o" g"*(el med)* *nd s+,,o"t)ng * st*nd o' eme"gent *;+*t)c (eget*t)on (=)# The t"*ys we"e ')lled w)th w*stew*te"% *nd then d"*)ned *'te" * ce"t*)n n+m-e" o' ho+"s ("*nge /2 to 46 ho+"s)# .n essence the ,"oced+"e w*s * ')ll *nd d"*w -*tch ty,e ,"ocess# E4cellent ,e"'o"m*nce w*s demonst"*ted 'o" 1OD < T!!% *nd N7%% *nd mode"*te ,e"'o"m*nce 'o" ,hos,ho"+s w)th * one2d*y 7$T (=) The ty,)c*l o"g*n)c lo*d)ng d+")ng these e4,e")ments (*t one2d*y 7$T) w*s *-o+t <6 kgHh*Hd (<2 .-H*cHd)% *nd the hyd"*+l)c lo*d)ng w*s *-o+t 6 cmHd (=#< )nHd)# Des)gn c")te")* -*sed on th)s wo"k (/E) )ncl+ded one d*y 7$T% *-o+t ')(e *c"es o' -ed s+"'*ce *"e* ,e" mgd% *nd +, to /<9/ *s,ect "*t)o (L9W)# These 8c")te")*% o" (*")*t)ons% h*(e -een w)dely *,,l)ed *nd% *s o' /00/% the"e we"e *-o+t E0 systems )n o,e"*t)on o" )n (*")o+s st*ges o' des)gn )n the so+th cent"*l 3#!#% -*sed on these (*l+es# These systems "*nge '"om on2s)te s)ngle '*m)ly +n)ts to l*"ge2sc*le m+n)c),*l systems (+, to 4 mgd) (/E)# Ge"s-e"gGs wo"k (4) w*s cond+cted o(e" * ,e")od o' se(e"*l ye*"s )n !*ntee% CA% )n l*"ge2sc*le% cont)n+o+s 'low% ')eld e4,e")ments +s)ng 0#FE m (2#< 't) dee, g"*(el -eds# The "emo(*l o' 1OD< T!!% *nd N7% w*s co""el*ted w)th the de,th o' "oot ,enet"*t)on 'o" the ,l*nt (*")et)es (Typha, Scirpus, Phragmites) w)th the -est "emo(*ls occ+"")ng w)th the dee,est "oot ,enet"*t)on (Scirpus then Phragmites). The o"g*n)c lo*d)ng w*s *,,"o4)m*tely << kgHh*Hd (40 .-H*cHd *nd the hyd"*+l)c lo*d)ng *-o+t < cmHd (2 )nHd)# Th)s hyd"*+l)c lo*d)ng )s e;+*l to /6 *cHmgd +s)ng the common 3#!# te"m# The 7$T )n th)s system w*s *-o+t s)4 d*ys% com,*"ed to only one d*y '"om Wol(e"tonGs (=) wo"k *nd ,oss)-ly +, to s)4 d*ys )n the new E+"o,e*n systems (/<)# 1eg)nn)ng )n the m)d /060s% the Tennessee @*lley A+tho")ty (T@A) -eg*n * ,"og"*m o' "ese*"ch *nd techn)c*l *ss)st*nce on const"+cted wetl*nds 'o" t"e*tment o' * (*")ety o' w*ste st"e*ms (m+n)c),*l w*stew*te"% *c)d m)ne d"*)n*ge% *g")c+lt+"*l w*stes *nd "+no''% etc#) (0)# The)" c")te")* 'o" s+-s+"'*ce 'low wetl*nds des)gned 'o" w*stew*te" t"e*tment% o")g)n*lly de")(ed '"om the wo"k o' K)ck+th (/6)% h*(e -een mod)')ed s)gn)')c*ntly )n s+-se;+ent ye*"s# 1y /00/ the"e *"e ,"o-*-ly *t le*st 60 s+-s+"'*ce 'low systems% )n o,e"*t)on )n * n+m-e" o' st*tes% -*sed on c")te")* *nd *ss)st*nce ,"o()ded -y T@A (20)# These systems "*nge )n s)5e '"om on2s)te s)ngle = '*m)ly +n)ts to l*"ge" m+n)c),*l systems (=F6< m Hd% / mgd)# The o"g*n)c lo*d)ng on one o' the e*"ly T@A systems (1enton% KD) w*s 6/ kgHh*Hd (F2 .-H*cHd) *nd the des)gn hyd"*+l)c lo*d)ng /4 cmHd (<#E )nHd) (=#E *cHmgd)#

22=

Ch*,te" 2 The theo"et)c*l 7$T *t th)s hyd"*+l)c lo*d)ng wo+ld -e *-o+t 2 d# At one o' the mo"e "ecently const"+cted systems (1e*" C"eek% AL) the o"g*n)c lo*d)ng )s *-o+t 4 kgHh*Hd (=#4 .-H*cHd) w)th * hyd"*+l)c lo*d)ng o' *-o+t = cmHd (/#2 )nHd)(=/ *cHmgd)# The theo"et)c*l 7$T% *t des)gn 'low% wo+ld -e *-o+t th"ee d*ys# The c+""ent T@A "ecommend*t)ons (/F) 'o" sm*ll2sc*le systems +s)ng * se,t)c t*nk *nd * -ed de,th o' 0#< m (/#< 't) *"e E2 kgHh*Hd (<E .-H*cHd) o"g*n)c lo*d)ng *nd < cmHd (/#6 )nHd) hyd"*+l)c lo*d)ng (20 *cHmgd)# The theo"et)c*l 7$T *t th)s hyd"*+l)c lo*d)ng )s *-o+t 4 d# T*-le / s+mm*")5es the (*")o+s des)gn *,,"o*ches d)sc+ssed *-o(e#

T*-le /# 7)sto")c*l Des)gn A,,"o*ches% E+"o,e*n *nd 3#!# !o+"ces

!o+"ce

O"g*n)c Lo*d)ng * (kgHh*Hd)

7yd"*+l)c Lo*d)ng (cmHd)

A"e* 2 = ( m H m Hd)

7"t (d)

E+"o,e 1oon (/06<) Coo,e" (/000) 3#!# Wol(e"ton (/06=) Ge"s-e"g (/#06<) T@A 1enton% KD (/060) 1e*" C"% AL (/00/)

/60 60

0 4

// 24

2#E E

<6 <<

6 <

/= 20

/ E

6/ 4

/4 =

F ==

2 =

*# kgHh*Hd 4 0#602 M .-H*cHd -# cmHd 4 0#=04 M )nHd c# m2Hm =Hd 4 2#00/ M *cHmgd

A com,*")son o' the d*t* ,"esented )n T*-le / )nd)c*tes the"e h*s -een no consens+s "eg*"d)ng des)gn c")te")* 'o" !: wetl*nds# Th)s o-()o+sly h*s * s)gn)')c*nt )m,*ct on system costs *nd m*y *''ect conce,t 'e*s)-)l)ty# The 3#!# E&A% *nd othe"s% +nde"took the )n(est)g*t)(e t*sks desc")-ed )n the .nt"od+ct)on to th)s "e,o"t% *nd the "es+lts o' those st+d)es *"e d)sc+ssed )n the ne4t sect)on#

224

Ch*,te" =

C7A&TE$ = &E$:O$ ANCE E@AL3AT.ON! Th)s sect)on com,*"es ,e"'o"m*nce e4,ect*t)ons 'o" the !:# conce,t to *ct+*l ')eld "es+lts o-t*)ned -y those st+d)es s,onso"ed -y the 3#!# E&A *nd othe"s% wh)ch we"e desc")-ed ,"e()o+sly# The d*t* '"om those sources *"e not s,ec)')c*lly )dent)')ed )n the g"*,h)c*l ,"esent*t)ons wh)ch 'ollow -+t *"e l)sted )n T*-le 2 -elow% *nd desc")-ed )n mo"e det*)l )n A,,end)4 1# The 'o+"teen systems l)sted )n T*-le 2 *"e -el)e(ed to -e "e,"esent*t)(e e4*m,les o' the systems )n o,e"*t)on )n the 3n)ted !t*tes# They we"e selected 'o" th)s *n*lys)s s)nce e*ch h*d * s)gn)')c*nt -ody o' "el*t)(ely "el)*-le )n,+tHo+t,+t w*te" ;+*l)ty d*t* wh)ch ch*"*cte")5es the ,e"'o"m*nce o' the wetl*nd com,onent )n the system# *ny othe" o,e"*t)ng systems only h*(e l)m)ted e''l+ent d*t* collected to (e")'y the)" com,l)*nce w)th N&DE! "e;+)"ements# All o' the d*t* shown )n the s+-se;+ent g"*,h)c*l ,"esent*t)ons *"e *(e"*ges o(e" the *(*)l*-le None o' these systems h*(e -een ,e")od o' "eco"d 'o" e*ch o' these systems# o,e"*t)ng longe" th*n ')(e ye*"s#

T*-le 2# D*t* !o+"ces 'o" &e"'o"m*nce E(*l+*t)on Loc*t)on G"eenle*(es% LA Deg+ss* Co#% ! 1e*" C"eek% AL onte"ey% @A Denh*m !,")ngs% LA 1enton% LA 7*+ghton% LA C*"()lle% LA *nde()lle% LA 1enton% KD * 7*"d)n% KD 7*"d)n% KD 3t)c*% !K 3t)c*% !
d

W*stew*te" Ty,e +n)c),*l .nd+st")*l Domest)c +n)c),*l +n)c),*l +n)c),*l 7os,)t*l +n)c),*l +n)c),*l +n)c),*l +n)c),*l +n)c),*l +n)c),*l +n)c),*l

Des)gn :low = 0 (m Hd ) <E4 EF=F <0 6= E<46 =F6 =60 4E< 4E== E6< 2=E /6E /60 4/E

T"e*tment A"e* f (ha) 0#44 0#60 0#20 0#02 E#/< 0#E/ 0#E/ 0#2E /#6< /#4E 0#=2 0#=2 0#E/ 0#6/

*# phragmites bed, -# Scirpus bed, c# No"th system% d# !o+th system e# m=Hd 4 (2#E4 4 l02E M mgd# '# 7* 4 2#4F M *c"es#

=2 /

Ch*,te" =

0O. 6 RE+O*A/ The ,hys)c*l "emo(*l o' 1OD< )s -el)e(ed to occ+" "*,)dly th"o+gh settl)ng *nd ent"*,ment o' ,*"t)c+l*te m*tte" )n the (o)d s,*ces )n the g"*(el o" "ock med)*# !ol+-le 1OD< )s "emo(ed -y the m)c"o-)*l g"owth on the med)* s+"'*ces *nd *tt*ched to the ,l*nt "oots *nd "h)5omes ,enet"*t)ng the -ed# !ome o4ygen )s -el)e(ed to -e *(*)l*-le *t m)c"os)tes on the s+"'*ces o' the ,l*nt "oots% -+t the "em*)nde" o' the -ed c*n -e e4,ected to -e *n*e"o-)c# &om5ared to ot4er forms of %aste%ater treatment7 -oth !: *nd :W! wetl*nd systems% *"e +n);+e )n th*t 1OD< )s *ct+*lly ,"od+ced w)th)n the system d+e to the decom,os)t)on o' ,l*nt l)tte" *nd othe" n*t+"*lly occ+"")ng o"g*n)c m*te")*ls# As * "es+lt% the systems c*n ne(e" *ch)e(e com,lete 1OD< "emo(*l *nd * "es)d+*l 1OD< '"om 2 to F mgHL )s ty,)c*lly ,"esent )n the e''l+ent# :)g+"e / ,"esents 1OD< )n,+t (e"s+s 1OD< o+t,+t d*t* 'o" the systems l)sted )n T*-le 2# All e''l+ent (*l+es *"e well -elow the 20 mgHL "e'e"ence le(el wh)ch )s * common ,e"m)t "e;+)"ement% *nd th)s c*n -e *ch)e(ed "eg*"dless o' the )n,+t concen2

40

:)g+"e /# 1OD< .n,+t @e"s+s O+t,+t#

=22

Ch*,te" =

D*t* '"om s)m)l*" systems )n E+"o,e show t"*t)on (w)th)n the "*nge shown)# essent)*lly the s*me "el*t)onsh), w)th )n,+t 1OD< concent"*t)ons +, to /<0 mgHL (=0)# The low (*l+es% )n the lowe" le't ,o"t)on o' the g"*,h% *"e )n'l+enced -y the ,"esence o' the "es)d+*l 1OD< d)sc+ssed *-o(e% wh)ch l)m)ts ')n*l e''l+ent le(els to * "*nge o' 2 to F mgHL#

:)g+"e 2# 1OD< $emo(*l @e"s+s 7yd"*+l)c $es)dence T)me

A com,*")son o' d)ssol(ed *nd tot*l 1OD< *nd COD 'o" )n'l+ent *nd e''l+ent *t two s)tes )n Lo+)s)*n* s+ggest th*t most o' the 1OD< le*()ng those systems w*s "es)d+*l o"g*n)cs '"om the system *nd not o' w*stew*te" o")g)n (2F)# :)g+"e 2 ,"esents 1OD< "emo(*ls (e"s+s the c*lc+l*ted 7$T 'o" these s*me systems# .t seems cle*" th*t *'te" one2 to one2 *nd one h*l'2d*y 7$T% the "emo(*l o' 1 O D< )s not st"ongly de,endent on 7$T s)nce "emo(*l )m,"o(es only sl)ghtly the"e*'te"% +, to *n 7$T o' F#< d# The E0 to E< ,e"cent "emo(*l (*l+es shown *t the one2d*y 7$T *"e not d+e to ,oo" 1OD< "emo(*l% -+t "*the" to "el*t)(ely low )n,+t le(els (see A,,end)4 1 'o" d*t*)# The lowest "emo(*l% *t 20 ,e"cent% )s d+e to *n in5ut 1 O D< ( < mgHL) wh)ch w*s *l"e*dy *t the th"eshold 'o" "es)d+*l# The 'o+"teen

=-=

Ch*,te" =

systems l)sted )n T*-le 2 *"e des)gn*ted -y s;+*"e sym-ols )n the ')g+"e> th"ee *dd)t)on*l systems% '"om othe" so+"ces% *"e *lso )ncl+ded to e4tend the "*nge o' 7$T shown# '4e 0O.6 removal values for t4ese data can #e reasona#l a55ro8imated # a first order 5lu" flo% relations4i5 u5 to a#out 9 2 d: The 1OD< "emo(*l the"e*'te" )s l)m)ted *nd )s -el)e(ed to -e )n'l+enced -y the ,"od+ct)on o' "es)d+*l 1OD< )n the system% *s ment)oned ,"e()o+sly# Th)s )s com,*t)-le w)th the hy,othes)s th*t 1OD < )s "emo(ed "*,)dly )n the '"ont ,*"t o' these systems% *nd s+ggests th*t the "emo(*ls% )nd)c*ted on the ')g+"e% *t the longe" detent)on t)mes m*y h*(e *ct+*lly -een o-t*)ned *t *n e*"l)e" ,o)nt )n the -ed ,")o" to s*m,l)ng *nd test)ng o' the ')n*l e''l+ent# .t h*s -een s+ggested )n the ,*st th*t these !: wetl*nd systems m+st h*(e * h)gh *s,ect "*t)o (L9W) to ens+"e m*)nten*nce o' ,l+g 'low cond)t)ons *nd h)gh le(els o' ,e"'o"m*nce (/E)# A common "ecommend*t)on )nd)c*ted th*t the L9W sho+ld -e *t le*st /09l *nd th*t lesse" le(els m)ght )m,*)" "emo(*l e'')c)ency# :)g+"e = tests th*t hy,othes)s -y com,*")ng the *(e"*ge 1OD< "emo(*l *ch)e(ed to the *s,ect "*t)o o' the (*")o+s systems l)sted )n T*-le 2#

:)g+"e =# !ystem As,ect $*t)o @e"s+s 1OD< $emo(*l#

=24

Ch*,te" =

.n these c*ses the *s,ect "*t)o (*")ed '"om less th*n 29/ to o(e" /F9/# As illustrated # t4e fi"ure7 t4ere does not a55ear to #e an relations4i5 #et%een as5ect The (e"y low "emo(*l *ssoc)*ted w)th the ratio and 0O.6 removal ca5a#ilities: h)ghest L9W (/F9/) )n the ,lot )s d+e to the (e"y low )n,+t 1OD< ( N < mgHL) *nd )s .n s+ch c*ses% '+"the" s)gn)')c*nt 1OD< "emo(*l not "el*ted to the *s,ect "*t)o# c*nnot -e e4,ected "eg*"dless o' *s,ect "*t)o o" 7$T# .n th)s c*se% *ny "ed+ct)on o' the w*stew*te" '"om *n )n,+t (*l+e o' < mgHL w*s ,"o-*-ly "e,l*ced% )n ,*"t% -y the "es)d+*l 1OD< '"om ,l*nt det")t+s# Othe" n*t+"*l t"e*tment systems% s+ch *s '*c+lt*t)(e l*goons *nd l*nd t"e*tment systems% h*(e d)s,l*yed * ne*" l)ne*" "el*t)onsh), -etween m*ss o"g*n)c lo*d)ng *nd m*ss "emo(*l "*tes% +, to "el*t)(ely h)gh lo*d)ng "*tes# :)g+"e 4 )ll+st"*tes th)s "el*t)onsh), 'o" !: wetl*nds *nd con')"ms th*t * l)ne*" 2 "el*t)onsh), does e4)st -etween these two ,*"*mete"s# The " (*l+e 'o" the c+"(e ')t )s 0#0F% )nd)c*t)ng *n e4cellent co""el*t)on#

:)g+"e 4# 1OD< Lo*d)ng @! 1OD< $emo(*l%

*ss 1*s)s#

=2<

Ch*,te" =

&aution is necessar %4en discussin" mass or"anic loadin"s on t4ese %etland s stems: The (*l+es shown on :)g+"e 4% *nd s)m)l*" (*l+es wh)ch c*n -e 'o+nd )n othe" "e'e"ences% *"e not the *ct+*l *"e*l o"g*n)c lo*d)ng on the system% -+t "*the" *"e the J*,,*"entK o"g*n)c lo*d)ngs o-t*)ned -y d)()d)ng the d*)ly o"g*n)c lo*d -y the tot*l s+"'*ce% *"e* o' the system# Th*t *,,"o*ch )m,l)es th*t the o"g*n)c lo*d )s *,,l)ed +n)'o"mly o(e" the ent)"e s+"'*ce *"e* o' the system# As d)sc+ssed ,"e()o+sly% m+ch o' the )n,+t sol)ds *nd 1OD< *"e ,"o-*-ly "emo(ed "*,)dly ne*" the '"ont end o' the system% so the *ct+*l o"g*n)c lo*d)ng 8on th)s 5one )s m+ch h)ghe" th*n on the "est o' the system# Th)s s)t+*t)on *lso ,"e(*)ls )n :W! wetl*nds% most '*c+lt*t)(e l*goons% *nd most o(e"l*nd 'low l*nd t"e*tment systems whe"e the )n'l+ent )s ty,)c*lly *,,l)ed# *t the he*d o' the t"e*tment +n)t# .n slow "*te l*nd t"e*tment systems whe"e s,")nkle"s *"e +sed to d)st")-+te the w*stew*te" o(e" the ent)"e t"e*tment s+"'*ce the J*,,*"entK o"g*n)c lo*d)ng m*y -e e;+*l to the *ct+*l o"g*n)c lo*d)ng# A 'ew :W! wetl*nd systems des)gned 'o" '+"the" ,ol)sh)ng o' h)ghly t"e*ted te"t)*"y e''l+ent *"e de*l)ng w)th low le(els o' essent)*lly sol+-le 1OD< *nd )n these c*ses the J*,,*"entK o"g*n)c lo*d)ng m*y *,,"o4)m*te the *ct+*l *"e*l o"g*n)c lo*d)ng## .n o(e"l*nd 'low systems de*l)ng w)th h)gh concent"*t)ons o' o"g*n)c sol)ds% s,")nkle"s *"e *lso +sed to ens+"e * mo"e +n)'o"m d)st")-+t)on o(e" the *(*)l*-le t"e*tment *"e*# .n wetl*nd systems% th)s ,+",ose co+ld -e *ch)e(ed w)th ste, 'eed o' the )n'l+ent *t mo"e th*n one ,o)nt *long the 'low ,*th to ens+"e * mo"e +n)'o"m lo*d)ng# Th)s non2+n)'o"m *,,l)c*t)on o' o"g*n)c w*stes com,l)c*tes de(elo,ment o' *n *cc+"*te *nd ,"ec)se des)gn model 'o" 1OD< "emo(*l% s)nce )t )s l)kely th*t the *ct+*l "emo(*l "*tes m*y (*"y *long the 'low ,*th% *nd% conc+""ently% "es)d+*l 1OD < )s -e)ng ,"od+ced '"om decom,os)ng ,l*nt det")t+s# The s)t+*t)on )s '+"the" com,l)c*ted )n th*t the only d*t* c+""ently *(*)l*-le *"e )n,+tHo+t,+t d*t* '"om * l)m)ted n+m-e" o' systems% some o' wh)ch h*(e * longe" 7$T th*n )s ,"o-*-ly necess*"y to *ch)e(e the me*s+"ed e''l+ent# '4e develo5ment of t4e ultimate desi"n model must %ait for collection of a sufficient #od of relia#le data descri#in" t4e internal 5erformance %it4in t4ese s stems: )n t4e interim7 some rational desi"n a55roac4 is necessar to ensure t4at t4ese s stems are cost-effective and can relia#l 5roduce t4e e85ected effluent ;ualit : The s*me s)t+*t)on ,"e(*)ls )n the des)gn o' o(e"l*nd 'low l*nd t"e*tment% '*c+lt*t)(e l*goons% *nd s)m)l*" *;+*t)c conce,ts# .n these c*ses% )t )s the consens+s o,)n)on th*t * ')"st o"de" ,l+g 'low model ,"o()des *n *cce,t*-le *nd "*t)on*l -*s)s 'o" des)gn# Ad(*nces h*(e -een m*de w)th l*goon systems% *nd mo"e com,le4 models *cco+nt)ng 'o" d)s,e"s)on *nd m)4)ng h*(e -een de(elo,ed# 7owe(e"% the ')"st o"de" ,l+g 'low model st)ll ,"e(*)ls *s the most commonly +sed#

=2E

Ch*,te" =

A first order 5lu" flo% model for 0O.6 removal also 4as #een used # a num#er of en"ineers for desi"n of t4ese S$ %etland s stems - in t4e United States7 Euro5e7 and Australia <=7>78797!07!27!37!?7!67!9720@: '4e "eneral form of t4e model is 5resented #elo%A

<!@ Whe"e9 Ce Co KT t KT K 20 T M E''l+ent 1OD< (mgHL) M ln'l+ent 1OD < (mgHL) M tem,e"*t+"e de,endent "*te const*nt (d2 ) M hyd"*+l)c "es)dence t)me (d) (T 2 20) M K20(/ #0E) 2/ M "*te const*nt *t 20o C% (d ) 2/ M /#/04 d M tem,e"*t+"e o' l);+)d )n the system ( C) o

A "*te const*nt K 20e; +*l to /#/04 d 'o" +se )n e;+*t)on (/) 'o" the des)gn o' !: const"+cted wetl*nds h*s -een ,"o,osed *nd ,+-l)shed )n se(e"*l so+"ces (E%F%6)# .nde,endent s+,,o"t 'o" th*t (*l+e c*n *lso -e 'o+nd )n othe" ,+-l)shed l)te"*t+"e (/0)# Th)s (*l+e )s -el)e(ed to -e conse"(*t)(e *nd )s *ssoc)*ted w)th *n J*,,*"entK o"g*n)c lo*d)ng on the system o' *-o+t //0 kgHh*Hd ( M 06 .-H*cHd)# The h)ghest J*,,*"entK o"g*n)c lo*d)ng shown on :)g+"e 4 )s *-o+t /4= kgHh*Hd (M /26 .-H*cHd) *nd the 2/ *ssoc)*ted J*,,*"entK "*te const*nt wo+ld -e *-o+t /#=6< d .n theo"y% )t sho+ld -e ,oss)-le to +se th)s h)ghe" (*l+e 'o" des)gn% -+t the mo"e conse"(*t)(e /#/04 d )s "ecommended s)nce the"e )s some )nde,endent s+,,o"t 'o" th*t (*l+e# Collect)on o' *dd)t)on*l ,e"'o"m*nce d*t* )n the '+t+"e m*y ,e"m)t '+"the" o,t)m)5*t)on *nd 2/ ,oss)-ly * s)gn)')c*nt )nc"e*se )n the /#/04 d "*te const*nt# .t )s -el)e(ed th*t the ,l+g 'low "*te const*nt 'o" these !: wetl*nds )s h)ghe" th*n those 'o" '*c+lt*t)(e l*goons o" 'o" :W! wetl*nds -ec*+se the s+"'*ce *"e* *(*)l*-le on the med)* )n the !: wetl*nds )s m+ch h)ghe" th*n )n the othe" two c*ses# Th)s s+"'*ce *"e* s+,,o"ts the de(elo,ment% *nd "etent)on% o' *tt*ched 2g"owth m)c"oo"g*n)sms wh)ch *"e -el)e(ed to ,"o()de most o' the t"e*tment "es,onses )n the system# T*-le = com,*"es the "*te const*nts 'o" these th"ee t"e*tment conce,ts% *t *n J*,,*"entK o"g*n)c lo*d)ng o' //0 kgHh*Hd (06 .-H*cHd)# The "*te const*nt 'o" the !: wetl*nd )s *-o+t *n o"de" o' m*gn)t+de h)ghe" th*n '*c+lt*t)(e l*goons% *nd *-o+t do+-le the (*l+e 'o" :W! wetl*nds#

2/

2/

=2F

Ch*,te" =

T*-le =# Com,*")son o' :)"st O"de" &l+g :low $*te Const*nts (F%//%40)

T"e*tment &"ocess

$*te Const*nt 2/ (d) /#/04 0#//F 0#<0/

!+-s+"'*ce :low Wetl*nd :*c+lt*t)(e L*goon :"ee W*te" !+"'*ce Wetl*nd

T!! $E O@AL !+s,ended sol)ds "emo(*l )s (e"y e''ect)(e )n !: const"+cted wetl*nds# ost o' the "emo(*l ,"o-*-ly occ+"s w)th)n the ')"st 'ew mete"s o' t"*(el d)st*nce '"om the )nlet 5one# :)g+"e < ,"esents the )n,+t T!! (e"s+s o+t,+t T!! 'o" the s)tes l)sted )n T*-le 2% w)th 20 mgHL shown *s * "e'e"ence )nde4# E4ce,t 'o" one e4c+"s)on (-el)e(ed d+e to e4tens)(e s+"'*ce 'low *nd sho"t c)"c+)t)ng)% *ll o' the systems ,"od+ce * ')n*l e''l+ent w)th less th*n 20 mgHL T!! "eg*"dless o' the )n,+t le(el (+, to //6 mgHL)# The systems w)th h)gh T!! )n,+t (*l+es (N <0 mgHl) ty,)c*lly h*(e '*c+lt*t)(e l*goons *nd the h)gh sol)ds *"e d+e to *lg*e c*""y2o(e" '"om the l*goon#

:)g+"e <# !+s,ended !ol)ds% .n,+t @e"s+s O+t,+t#

=26

Ch*,te" =

:)g+"e E com,*"es the T!! "emo(*l "*te to the 7$T 'o" the systems e4*m)ned# The "el*t)onsh), )s s)m)l*" to th*t shown on :)g+"e 2 'o" 1OD< )n th*t *'te" *n 7$T o' one d*y the"e )s l)ttle )m,"o(ement )n "emo(*l o' s+s,ended sol)ds#

:)g+"e E# !+s,ended !ol)ds $emo(*l @e"s+s 7$T#

:)g+"e F# !+s,ended !ol)ds $emo(*l @e"s+s !ystem As,ect $*t)o#

=20

Ch*,te" =

:)g+"e F com,*"es the T!! "emo(*l "*te to the *s,ect "*t)o o' the (*")o+s systems# '4ese results are similar to t4ose s4o%n in $i"ure 3 for 0O.6 and indicate no relations4i5 #et%een t4e s stem as5ect ratio and 'SS removal: A k)net)c des)gn model )s not *(*)l*-le 'o" T!! "emo(*l# 7owe(e"% -*sed on the "el*t)onsh),s )ll+st"*ted )n :)g+"es / to F% )t )s *,,*"ent th*t T!! "emo(*l 'ollows Th)s s+ggests th*t when * system )s des)gned 'o" * the s*me ,*tte"n *s 1OD<# ,*"t)c+l*" le(el o' 1OD< "emo(*l% the T!! "emo(*l w)ll -e com,*"*-le *s long *s s+-s+"'*ce 'low )s m*)nt*)ned )n the -ed#

-)'RO1E- RE+O*A/ The "emo(*l o' non2)on)5ed *mmon)* )s ty,)c*lly the m*Bo" n)t"ogen ,*"*mete" o' conce"n d+e to )ts to4)c)ty 'o" ')sh *nd othe" *;+*t)c *n)m*ls% *nd to )ts *dded o4ygen dem*nd on "ece)()ng st"e*ms# *ny o' the e*"l)est !: wetl*nd systems we"e only "e;+)"ed to "emo(e 1OD< *nd T!! *nd h*(e done so s+ccess'+lly# .n some c*ses% the)" ,e"m)ts h*(e s)nce -een "e()sed to "e;+)"e *mmon)* "emo(*l# *ny o' the new systems *lso h*(e *mmon)* l)m)ts (de,end)ng on "ece)()ng w*te"# "e;+)"ements)# The n)t"ogen ente")ng wetl*nd systems c*n -e me*s+"ed *s o"g*n)c n)t"ogen *nd *mmon)* (e4,"essed *s TKN)% o" *s n)t"*te% o" * com-)n*t)on o' -oth n)t"ogen me*s+"ements# !e,t)c t*nks% ,")m*"y t"e*tment systems% *nd '*c+lt*t)(e l*goon e''l+ents do not +s+*lly cont*)n n)t"*te% -+t c*n h*(e s)gn)')c*nt le(els o' o"g*n)c N *nd *mmon)*# D+")ng the w*"m s+mme" months% '*c+lt*t)(e l*goons c*n h*(e low le(els o' *mmon)* )n the e''l+ent% -+t o'ten cont*)n h)gh concent"*t)ons o' o"g*n)c N *ssoc)*ted w)th the *lg*e le*()ng w)th the e''l+ent# Ae"*ted second*"y t"e*tment system e''l+ents ty,)c*lly h*(e low le(els o' o"g*n)c N -+t cont*)n s)gn)')c*nt !ystems w)th h)gh )ntens)ty o" long2te"m# concent"*t)ons o' *mmon)* *nd n)t"*te# *e"*t)on c*n h*(e most o' the n)t"ogen )n the n)t"*te 'o"m# The o"g*n)c N ente")ng * !: wetl*nd )s ty,)c*lly *ssoc)*ted w)th ,*"t)c+l*te m*tte" s+ch *s o"g*n)c w*stew*te" sol)ds *ndHo" *lg*e# The ,l*nt det")t+s *nd othe" n*t+"*lly occ+"")ng o"g*n)c m*te")*ls )n the wetl*nd c*n *lso -e * so+"ce 'o" o"g*n)c N# .ecom5osition and mineraliBation 5rocesses in t4e %etland %ill convert a si"nificant 5art of t4is or"anic - to ammonia: 1)olog)c*l n)t")')c*t)on 'ollowed -y den)t")')c*t)on )s -el)e(ed to -e the m*Bo" ,*thw*y 'o" *mmon)* "emo(*l )n -oth ty,es o' const"+cted wetl*nds% *s they *"e

=2/0

Ch*,te" =

,"esently o,e"*ted (4%F%/0)# &l*nt t)ss+e *n*lys)s *t se(e"*l loc*t)ons )nd)c*te th*t * s)ngle *nn+*l h*"(est o' the ,l*nt m*te")*l m)ght *cco+nt 'o" ten ,e"cent o" less o' the A mo"e '"e;+ent h*"(est)ng ,"og"*m n)t"ogen2 "emo(ed -y the system (F%22%2=)# m)ght )nc"e*se th)s ,otent)*l% -+t )t wo+ld *lso )nc"e*se the costs 'o" o,e"*t)on o' the system## :)g+"e 6 ,"esents *mmon)* )n,+t (e"s+s o+t,+t d*t* 'o" the systems )ncl+ded )n th)s st+dy wh)ch h*(e * cont)n+o+s d)sch*"ge *nd w)tho+t "ecycle# The l)ne on the g"*,h )nd)c*tes the cond)t)on when )n,+t e;+*ls o+t,+t# One h*l' o' the systems *"e *t o" *-o(e th*t l)ne% )nd)c*t)ng th*t the"e )s * net ,"od+ct)on o' *mmon)* *s the w*stew*te" ,*sses th"o+gh the -ed# The so+"ce o' th)s Je4t"*K *mmon)* )s -el)e(ed to -e '"om the *n*e"o-)c decom,os)t)on o' the o"g*n)c n)t"ogen t"*,,ed )n the -ed *s !)nce the -ed )s *n*e"o-)c% the"e )s then )ns+'')c)ent o4ygen ,*"t)c+l*te m*tte"# *(*)l*-le )n the -ed to o4)d)5e th)s *mmon)* to n)t"*te# :)g+"e 0 ,"esents *mmon)* "emo(*l 'o" some o' the systems (e"s+s 7$T# The "es+lts 'o" se(e"*l systems (Denh*m !,")ngs% LA 'o" e4*m,le% N7% )n M 0#F mgHL% N7% o+t M /0 mgHL% "emo(*l M 2 /=F0L) *"e -elow the lowe" l)m)t on the g"*,h *nd *"e the"e'o"e not shown# One ,o)nt (the o,en s;+*"e )n the +,,e" ")ght co"ne") "e,"esents d*t* '"om !*ntee% CA> the "em*)nde" *"e d*t* '"om the T*-le 2 systems#

:)g+"e 6# Ammon)* .n,+t @e"s+s O+t,+t#

=2//

Ch*,te" =

:)g+"e 0# Ammon)* $emo(*l @e"s+s 7$T

ost o' the systems shown on :)g+"e 0 d)s,l*y * m*"g)n*l o" * neg*t)(e *mmon)* "emo(*l "*te "eg*"dless o' the detent)on t)me )n the system# Two systems% shown *s s;+*"es )n the ')g+"e% d)s,l*y (e"y h)gh "emo(*l "*tes *t 7$T le(els com,*"*-le to the othe" systems# '4e difference is #elieved to #e t4e lacC of al"ae7 t4e availa#ilit of o8 "en7 and sufficient 2R' in t4e latter t%o s stems7 so t4at 4i"4 levels of nitrification can occur in t4ese #eds: The ,")m*"y o4ygen so+"ce )n these two c*ses )s -el)e(ed to -e '"om the 8"oots o' the eme"gent *;+*t)c (eget*t)on# .n the ')"st c*se% (1e*" C"eek% AL) the -ed )s only 0#= m (/ 't) dee, *nd s+,,o"ts * st*nd o' Typha w)th the "oots o-se"(ed ,enet"*t)ng to the -ottom o' the -ed> *mmon)* "emo(*l "e*ches 60 ,e"cent w)th *n 7$T o' =#0 d# The second c*se )s the Scirpus -ed *t the !*ntee% CA ,)lot system% whe"e the "oots *lso ,enet"*ted to the -ottom o' the 0#FE m (2#< 't) dee, -ed> *mmon)* "emo(*ls o' 04 ,e"cent we"e *ch)e(ed w)th *n 7$T o' se(en# d*ys (4)# .t )s *lso )n'o"m*t)(e to com,*"e the 1e*" C"eek "es+lts +s)ng Typha to the 0#FE m2dee, -ed *t !*ntee% CA wh)ch *lso s+,,o"ted * st*nd o' Typha. )n t4e latter case7 the ,l*nt "oots only ,enet"*ted to 0#= m (s*me de,th *s *t 1e*" C"eek) *nd the *mmon)* "emo(*l w*s only 20 ,e"cent w)th the F d 7$T# .n the Typha -ed *t !*ntee% *-o+t E0 ,e"cent o' the 'low ,*ssed th"o+gh the -ed -elow the "oot 5one whe"e o4ygen w*s not l)kely to -e ,"esent *nd l)m)ted *mmon)* "emo(*l w*s

=2/2

Ch*,te" =

*ch)e(ed# At 1e*" C"eek% the ent)"e 'low ,*ssed th"o+gh the Typha "oot 5one *nd 60 ,e"cent *mmon)*% "emo(*l w*s ,"od+ced )n =#0 d# Th)s st"ongly s+,,o"ts the hy,othes)s th*t the ,l*nt "oots )n these !: wetl*nd -eds *"e the ,")m*"y so+"ce o' o4ygen needed 'o" n)t")')c*t)on o' *mmon)* *nd othe" -)ochem)c*l "es,onses% *nd th*t )t )s the"e'o"e essent)*l to -")ng the w*stew*te" )nto d)"ect cont*ct w)th the "oot 5one# T*-le 4 s+mm*")5es the s)te cond)t)ons *nd the *mmon)* "emo(*l ,e"'o"m*nce o' the /4 systems +sed )n th)s *n*lys)s# .t )s cle*" '"om *n e4*m)n*t)on o' these d*t* th*t systems w)th no *lg*e% w)th longe" detent)on t)mes% *nd w)th dee, "oot ,enet"*t)on ,"od+ce the -est *mmon)* "emo(*l "es+lts# The two systems )n the l)st (!*ntee *nd 1e*" C"eek) wh)ch )nco",o"*te *ll th"ee '*cto"s ,"od+ced the -est "es+lts o' *ll# T*-le 4# Ammon)* $emo(*l )n !: Wetl*nds#

Loc*t)on

Ammon)* $emo(*l L 2 /=26 2<<4 222 24< 2<0 2/4 /6 2 <F 4< 4< E 60 04

Alg*e &"esent

7$T d

1ed De,th m 0#E/ 0#FE 0#FE 0#E/ 0#E/ 0#E/ 0#E/ 0#E/ 0#E4 0#E4 0#E/ 0#0/ 0#=0 0#E/

$oot De,th L <0 <0 <0 40 <0 <0 <0 40 E0 E0 <0 =0 /00 /00

Denh*m !,")ngs% LA 7*+ghton% LA C*"()lle% LA 1enton% KD *nde()lle% LA G"eenle*(es% LA 7*"d)n% KD (-+l"+sh) 7*"d)n% KD ("eeds) 3t)c*% ! (no"th) 3t)c*% ! (so+th) Deg+ss* Co",#% AL onte"ey% @A 1e*" C"eek% AL !*ntee% CA (Scitpus)

Des Des Des Des No No No No Des Des No No No No

/ 4#< /#4 < 0#F / =#= =#= < =#F / 0#0 =#0 F

*# $oot de,th e4,"essed *s * ,e"cent*ge o' tot*l -ed de,th#

The e*"ly )n(est)g*to"s% *nd des)gne"s )n the 3#!# *nd E+"o,e% -el)e(ed th*t o4ygen '"om the ,l*nt "oots wo+ld -e *(*)l*-le th"o+gho+t the !: wetl*nd -ed# .m,l)c)t )n th*t -el)e' )s the *ss+m,t)on th*t the ,l*nt "oots wo+ld ,enet"*te the '+ll

=2 /=

Ch*,te" = de,th o' the -ed# A ,"oced+"e *d(oc*ted -y K)ck+th (<) to *ch)e(e th*t "es+lt w*s to lowe" the w*te" le(el )n the -ed d+")ng the '*ll o' the ye*"% 'o" th"ee s+ccess)(e ye*"s% to )nd+ce m*4)m+m "oot ,enet"*t)on# Th*t ,"oced+"e h*s not -een *ttem,ted )n the 3#!# to d*te# The med)* de,th )n most o' the -eds )n the 3#!# )s *-o+t 0#E m (2 '2t)% -+t )n most c*ses% the ,l*nt "oots h*(e -een o-se"(ed to ,enet"*te only to 0#= m (/ 't) o" less# Dee,e" ,enet"*t)ons h*(e -een o-se"(ed when n+t")ent le(els )n the w*te" *"e low o" when the ,l*nts *"e loc*ted *t the s)des o' the cells *nd othe" ,oss)-le Jde*d s,otsK w)th less 'low th*n the m*)n ,o"t)on o' the -ed# As * "es+lt% *-o+t h*l' o' the 'low )n most 3#!# systems occ+"s )n * 5one whe"e o4ygen )s not l)kely to -e ,"esent *nd n)t")')c*t)on c*nnot occ+"# The "es+lts shown 'o" most o' the d*t* ,o)nts )n :)g+"e 0 *"e ty,)c*l e4,ect*t)ons 'o" the c+""ent mode o' !: wetl*nd system o,e"*t)on *nd To ens+"e s)gn)')c*nt n)t")')c*t)on )n these systems% )t w)ll -e -ed con')g+"*t)on# necess*"y to de(elo, *n *,,"o,")*te o4ygen so+"ce# :+"the" d)sc+ss)on on th*t to,)c )s ,"o()ded )n * l*te" sect)on o' th)s "e,o"t# :)g+"e /0 com,*"es the m*ss "emo(*l "*te 'o" tot*l KBeld*hl n)t"ogen (TKN) to the m*ss lo*d)ng (most o' the systems )n T*-le 2 h*(e no TKN d*t*)# TKN )s essent)*lly e;+*l to tot*l n)t"ogen (TN) )n these c*ses s)nce the"e )s ty,)c*lly l)ttle n)t"*te ente")ng o" le*()ng the !: systems# The l)ne shown on the ')g+"e )s the "es+lt o' * "eg"ess)on *n*lys)s 'o" :W! wetl*nd systems 'o" these s*me ,*"*mete"s (24)#

:)g+"e /0# TKN

*ss Lo*d)ng @e"s+s

*ss $emo(*l

=2/4

Ch*,te" =

The"e )s no *,,*"ent "el*t)onsh), -etween m*ss lo*d)ng o' TKN *nd "emo(*l 'o" the s)4 !: systems whe"e d*t* we"e *(*)l*-le# All -+t one o' these d*t* ,o)nts *"e s)gn)')c*ntly -elow the :W! l)ne% )nd)c*t)ng th*t these !: systems *"e less e'')c)ent *t TKN (o" TN) "emo(*l th*n :W! systems# The d)''e"ence )s *g*)n -el)e(ed to -e the .n :W! systems% the w*te" s+"'*ce )s e4,osed to the *(*)l*-)l)ty o' o4ygen# *tmos,he"e *nd some d)"ect o4ygen t"*ns'e" )s ,oss)-le# The only d*t* ,o)nt on :)g+"e /0 wh)ch )s close to the l)ne )s the 1e*" C"eek% AL system% whe"e (*s d)sc+ssed ,"e()o+sly) o4ygen '"om the ,l*nt "oots )s *,,*"ently *(*)l*-le )n th)s sh*llow -ed (0#=m) to s+,,o"t n)t")')c*t)on# .t h*s -een s+ggested th*t the e''l+ent *mmon)* '"om these wetl*nd systems )s "el*ted to the m*ss lo*d)ng o' TKN o" TN on the system (4/)# :)g+"e // ,"esents th)s com,*")son 'o" s)4 o' the T*-le 2 !: systems whe"e s+'')c)ent d*t* we"e *(*)l*-le# The "eg"ess)on c+"(e o' -est ')t )s *lso shown% -+t the low " (*l+e )nd)c*tes th*t the co""el*t)on )s not (e"y s)gn)')c*nt# A m)ss)ng element )n th)s *,,"o*ch )s the "es)d+e '"om decom,os)t)on o' ,l*nt m*tte" )n the system s)nce the TKN lo*d)ng )s only * me*s+"e o' n)t"ogen )n the ente")ng w*stew*te"# :)g+"e // s+ggests th*t * TKN m*ss lo*d)ng o' less th*n 2 kgHh*Hd (/#6 .-H*cHd) wo+ld -e necess*"y to cons)stently *ch)e(e *n e''l+ent *mmon)* o' 2 to = mgHL )n !: wetl*nds *s they *"e c+""ently o,e"*ted w)th *n o4ygen de')c)ency#

TKN A!! LOAD.NG (k gHh*Hd)

:)g+"e //# E''l+ent Ammon)* @e"s+s TKN

*ss Lo*d)ng

=2/<

Ch*,te" =

*ny o' the olde" systems )n the G+l' !t*tes +sed so't t)ss+e 'lowe")ng ,l*nts 'o" *esthet)c "e*sons# The)" decom,os)t)on )s (e"y "*,)d )n the '*ll *nd *'te" * '"ost% *nd me*s+"*-le )nc"e*ses )n e''l+ent 1OD< *nd *mmon)* c*n -e o-se"(ed (2<)# The s*me e''ect )s l)kely when s)gn)')c*nt s+"'*ce 'low )s *llowed on these systems> s+"'*ce 'low w)ll "es+lt )n * m+ch mo"e "*,)d -"e*kdown o' ,l*nt det")t+s *nd "ele*se o' *mmon)* to the w*te"# .' the s+"'*ce o' the -ed )s m*)nt*)ned )n * d"y cond)t)on (e4ce,t d+")ng "*)n'*ll e(ents)% ,l*nt det")t+s w)ll decom,ose m+ch mo"e slowly#

&7O!&7O$3! $E O@AL :)g+"e /2 ,"esents ,hos,ho"+s )n,+t (e"s+s o+t,+t d*t* 'o" the systems whe"e d*t* we"e *(*)l*-le# The slo,)ng l)ne on the ')g+"e "e,"esents the cond)t)on whe"e )n,+t e;+*ls o+t,+t# Two o' the systems '*ll on th*t l)ne *nd se(e"*l othe"s show m*"g)n*l "emo(*l c*,*-)l)t)es# Only one d*t* ,o)nt shows e4cellent "emo(*l 22 the 1e*" C"eek% AL system# The med)* )n th)s c*se *"e ')ne ")(e" g"*(el% *nd the ,"esence o' o4)des o' )"on *nd *l+m)n+m *ssoc)*ted w)th th)s med)* m*y -e "es,ons)-le 'o" the 0< ,e"cent "emo(*l o' ,hos,ho"+s o-se"(ed d+")ng the ')"st ye*" o' system o,e"*t)on#

:)g+"e /2# &hos,ho"+s .n,+t @e"s+s O+t,+t

=2/E

Ch*,te"= &hos,ho"+s "emo(*l )n most const"+cted wetl*nd systems )s not (e"y e''ect)(e -ec*+se o' the l)m)ted cont*ct o,,o"t+n)t)es -etween the w*stew*te" *nd the so)l# !ome e4,e")ment*l *nd de(elo,ment*l wo"k h*s -een +nde"t*ken +s)ng e4,*nded cl*y *gg"eg*tes *nd the *dd)t)on o' )"on *nd *l+m)n+m o4)des> some o' these t"e*tments m*y h*(e ,"om)se -+t the long2te"m e4,ect*t)ons h*(e not -een de')ned# !ome systems )n E+"o,e +se s*nd )nste*d o' g"*(el to )nc"e*se the ,hos,ho"+s "etent)on c*,*c)ty% -+t select)ng th)s med)* "es+lts )n * l*"ge" system -ec*+se o' the "ed+ced hyd"*+l)c cond+ct)()ty o' s*nd com,*"ed to g"*(el# )f si"nificant 54os54orus removal is a 5roDect re;uirement7 t4en ver lar"e land areas or alternative treatment met4ods %ill 5ro#a#l #e re;uired:

$E&A/ &O/)$OR+ RE+O*A/ '4ese S$ %etland s stems are7 in t4e "eneral case7 ca5a#le of a one- to t%olo" reduction in fecal coliforms7 %4ic4 in man cases is not enou"4 to routinel satisf disc4ar"e re;uirements %4ic4 often s5ecif E 200F!00 ml: &e*k 'lows )n "es,onse to )ntense "*)n'*ll e(ents *lso d)s"+,t "emo(*l e'')c)enc)es 'o" 'ec*l col)'o"ms# As * "es+lt% most o' the systems l)sted )n T*-le 2 +t)l)5e some 'o"m o' ')n*l d)s)n'ect)on# One e4ce,t)on )s the l)ghtly lo*ded system )n 1e*" C"eek% AL% wh)ch +ses * sm*ll s)5ed2")(e" g"*(el *s the -ed med)*# At 1e*" C"eek the 'ec*l col)'o"ms *"e "ed+ced 4 '"om 6 4 /0 H/00 ml to /0Hl00 ml o" less on *n *(e"*ge -*s)s#

=2/F

Ch*,te" 4

C7A&TE$ 4 .ES)1- &O-S).ERA')O-S

The m*Bo" conce"ns )n the des)gn o' !: const"+cted wetl*nds )ncl+de9

7yd"*+l)c *nd hyd"olog)c*l cond)t)ons% 1OD< *nd T!! "emo(*l mech*n)sms% N)t"ogen "emo(*l e'')c)ency% @eget*t)on select)on *nd m*n*gement% Const"+ct)on det*)ls% *nd

2,.RAU/)&S G 2,.RO/O1, A -*s)c )ntent o' the !: wetl*nd t"e*tment conce,t )s the m*)nten*nce o' 'low2 7owe(e"% * s)gn)')c*nt n+m-e" o' -ene*th the s+"'*ce o' the med)* )n the -ed# o,e"*t)ng !: const"+cted wetl*nds *"e e4h)-)t)ng (*"y)ng deg"ees o' s+"'*ce 'low on to, o' the med)* -ed# !)nce these systems we"e des)gned 'o" com,lete s+-s+"'*ce 'low% th)s cond)t)on "e,"esents * ,otent)*l des)gn de')c)ency# .t h*s -een s+ggested th*t th)s s+"'*ce 'low )s d+e to clogg)ng o' the (o)d s,*ces )n the -ed e)the" -y the (eget*t)(e "oots *nd *ssoc)*ted ,l*nt m*te")*ls o" -y the *cc+m+l*t)on o' s+s,ended sol)ds se,*"*ted '"om the w*stew*te" st"e*m# 7owe(e"% most o' these systems h*(e -een )n o,e"*t)on 'o" less th*n ')(e ye*"s *nd s+"'*ce 'low w*s o-se"(ed *t m*ny soon *'te" 'low commenced#

0E. &/O11)-1 A ,"el)m)n*"y% +n,+-l)shed /000 )n(est)g*t)on -y $eed s+ggested * "el*t)onsh), -etween the o"g*n)c lo*d)ng on the c"oss sect)on o' the -ed *t the ent"y 5one *nd o-se"(ed s+"'*ce 'low on the !: wetl*nd -ed# The *ss+m,t)on w*s th*t clogg)ng *t the ent"y 5one w*s c*+s)ng the s+"'*ce 'low# A c"oss sect)on*l lo*d)ng o' N 0#< kg

42l

Ch*,te" 4
2 2

1 O D<H m Hd (0#/ l- 1OD<H't Hd) w*s *ssoc)*ted w)th no o-se"(ed s+"'*ce 'low# 2 !ystems w)th o-se"(ed s+"'*ce 'low h*d h)ghe" o"g*n)c lo*d)ngs% O 0#< kgHm Hd# 3n'o"t+n*tely% th)s *,,*"ent "el*t)onsh), h*s now -een ,+-l)shed )n * n+m-e" o' so+"ces *nd h*s -ecome ,*"t o' some des)gn g+)del)nes (/F)# !+-se;+ent )n(est)g*t)ons *t the o")g)n*l s)tes h*(e )nd)c*ted th*t the o-se"(ed s+"'*ce 'low *t most o' the systems c*n -e e4,l*)ned -y )n*de;+*te hyd"*+l)c des)gn *nd )n*ttent)on to the "e;+)"ements o' D*"cyGs L*w (desc")-ed -elow)# The o"g*n)c lo*d)ng *,,"o*ch m*y h*(e some me")t )n th*t * "ed+ced o"g*n)c lo*d)ng on the c"oss sect)on sho+ld ce"t*)nly "ed+ce the ,otent)*l 'o" clogg)ng# The"e *"e% howe(e"% no d*t* *(*)l*-le *t ,"esent to s+,,o"t the select)on o' * s,ec)')c c"oss sect)on*l o"g*n)c lo*d)ng# The net *''ect o' th)s *,,"o*ch )s to )nc"e*se the c"oss sect)on*l *"e* o' the -ed *nd the"e-y "ed+ce the *s,ect (L9W) "*t)o# Th*t s*me "es+lt c*n -e *ch)e(ed% )n * mo"e "*t)on*l m*nne"% -y ,"o,e" *,,l)c*t)on o' D*"cyGs L*w# &)ts h*(e -een e4c*(*ted )n s)4 o' these !: systems (two )n Kent+cky% 'o+" )n Lo+)s)*n*) to o-se"(e *ny clogg)ng s+-st*nces% *nd to dete"m)ne the)" ch*"*cte")st)cs (2E%2F%26)# At only one Kent+cky s)te% -y A+ne /000% * ,e"s)stent gel*t)no+s s+-st*nce h*d *lmost com,letely clogged the (o)d s,*ces )n the ')"st 2< ,e"cent o' the -ed# L*-o"*to"y tests )nd)c*ted th*t th)s m*te")*l w*s *-o+t 60 ,e"cent )no"g*n)c% w)th th*t '"*ct)on com,osed o' s)l)c*% cl*y m)ne"*lsG% *nd l)mestone d+st# The clogg)ng *t th)s s)te occ+""ed "*,)dly d+")ng the ')"st ye*" o' o,e"*t)on *nd d)d not s)gn)')c*ntly e4,*nd )n *"e* )n s+-se;+ent ye*"s# &)ts e4c*(*ted *t the s*me loc*t)ons )n /002 showed no e()dence o' gel*t)no+s s+-st*nces *nywhe"e )n the -ed# .t )s l)kely th*t th)s )sol*ted c*se o' se(e"e clogg)ng m*y h*(e -een d+e to the o(e"lo*ded cond)t)on o' the -ed d+")ng )ts ')"st ye*" o' o,e"*t)on# At the 'o+" s)tes )n Lo+)s)*n*% *nd the second s)te )n Kent+cky% the s+s,ended m*tte" )n the "ock (o)ds w*s not gel*t)no+s )n ch*"*cte" *nd w*shed e*s)ly '"om the "ock s+"'*ces (2F%26/# .t w*s s)m)l*" )n *,,e*"*nce to * m)4ed l);+o" s*m,le% w)th * sl)ght odo" )n some c*ses# At th"ee o' the 'o+" s)tes )n Lo+)s)*n*% the sol)ds ,"esent occ+,)ed less th*n two ,e"cent o' the (o)d s,*ce *(*)l*-le 'o" 'low o' w*te"> )n the wo"st c*se the sol)ds ,"esent occ+,)ed *-o+t s)4 ,e"cent o' the *(*)l*-le (o)d s,*ces *t * loc*t)on close to the )nlet ,),e# .n *ll c*ses% these sol)ds we"e *t le*st 60 ,e"cent &l*nt "oots *nd "el*ted det")t+s we"e not enco+nte"ed -elow )no"g*n)c m*te")*l# de,ths o' *-o+t 0#= m (/ 't) )n *ny o' these systems (2F%26/# As * "es+lt% *t these ')(e s)tes )t does not *,,e*" th*t *cc+m+l*t)on o' T!! o" ,l*nt det")t+s we"e "es,ons)-le 'o" clogg)ng o" 'o" *ny s+"'*ce 'low wh)ch m*y h*(e occ+""ed# At *ll s)4 o' the s)tes )n(est)g*ted% the "ock med)* we"e del)(e"ed -y t"+ck o(e" +n,*(ed "o*ds% )n *ll k)nds o' we*the"% *nd% *s desc")-ed -y the o,e"*to"s% the t"+cks tended to 'ollow the s*me ,*thw*y ente")ng *nd le*()ng the wetl*nd -ed# .t )s ;+)te

422

Ch*,te" 4

,oss)-le th*t * l*"ge ,o"t)on o' the )no"g*n)c sol)ds o-se"(ed )n the (o)d s,*ces o' the med)* w*s d+e to so)l '"om the t"+ck t)"es% *nd so)l% "ock d+st *nd ')nes '"om the "ock med)* t"*ns,o"ted )n the t"+ck# At the 'o"me"ly ,*"t)*lly clogged Kent+cky s)te% these )no"g*n)c m*te")*ls m*y h*(e then t"*,,ed *lg*l sol)ds ente")ng the -ed% "es+lt)ng )n 'o"m*t)on o' the gel*t)no+s m*te")*l c"e*t)ng the clogg)ng# The '*ct th*t the clogged 5one ne(e" e4,*nded -eyond the ')"st 2< ,e"cent o' the -ed% *nd th*t the gel*t)no+s m*te")*l h*s now d)s*,,e*"ed% s+ggests th*t const"+ct)on *ct)()ty m*y h*(e -een the ,")m*"y c*+se o' the clogg)ng )nste*d o' * cont)n+)ng -)ochem)c*l "e*ct)on#

2,.RAU/)& .ES)1When s+-s+"'*ce 'low cond)t)ons *"e e4,ected )n the !: wetl*nd -ed )t )s common ,"*ct)ce to +se D*"cyGs L*w% wh)ch desc")-es the 'low "eg)me )n * ,o"o+s med)*# D*"cyGs L*w )s ty,)c*lly de')ned w)th e;+*t)on (2)#

I Whe"e9 I ks A !

M k! A !
= =

(2)

M 'low ,e" +n)t t)me% m Hd ('t Hd)% o" (g*lHd)% etc# M hyd"*+l)c cond+ct)()ty o' * +n)t *"e* o' the med)+m to the 'low d)"ect)on% m H m H d ,e",end)c+l*" = 2 ('t H't Hd)% o" (g*lHd)% etc# M tot*l c"oss2sect)on*l *"e*% ,e",end)c+l*" to 'low% m 2 ('t )# M hyd"*+l)c g"*d)ent o' the w*te" s+"'*ce )n the 'low system dhHdL% mHm% ('tH't)# (All +n)ts m+st -e cons)stent)

D*"cyGs L*w )s not st")ctly *,,l)c*-le to s+-s+"'*ce 'low wetl*nds -ec*+se o' ,hys)c*l l)m)t*t)ons )n the *ct+*l system# .t *ss+mes l*m)n*" 'low cond)t)ons% wh)ch m*y not -e the c*se when l*"ge "ock o" (e"y co*"se g"*(el *"e +sed *s the med)*# T+"-+lent 'low w)ll occ+" )n these co*"se med)* when the hyd"*+l)c des)gn )s -*sed D*"cyGs L*w *lso *ss+mes th*t the 'low (I) )n the on * h)gh hyd"*+l)c g"*d)ent# system )s const*nt *nd +n)'o"m% -+t )n the *ct+*l c*se )n * !: wetl*nd the )n,+t (e"s+s o+t,+t I m*y (*"y d+e to ,"ec),)t*t)on% e(*,o"*t)on% *nd see,*ge> *nd sho"t c)"c+)t)ng o' 'low m*y occ+" d+e to +ne;+*l ,o"os)ty o" ,oo" const"+ct)on# Ail of t4ese factors limit t4e t4eoretical a55lica#ilit of .arc Hs /a%7 #ut it remains as t4e .' sm*ll to onl reasona#l accessi#le model for desi"n of t4ese S$ s stems: mode"*te s)5ed g"*(el ( N 4 cm) )s +sed *s the med)*% )' the system )s ,"o,e"ly const"+cted to m)n)m)5e sho"t c)"c+)t)ng% )' the system )s des)gned to de,end on *

42=

Ch*,te" 4 m)n)m*l hyd"*+l)c g"*d)ent% *nd if t4e I in e;uation <2@ is considered to #e t4e Javera"eK flo% <LIin M IoutlF2@ in t4e s stem to account for an "ains or losses due to 5reci5itation7 eva5oration or see5a"e7 then D*"cyGs L*w c*n ,"o()de * "e*son*-le *,,"o4)m*t)on o' the hyd"*+l)c cond)t)ons )n these !: -eds# !ome o' the const"*)nts on D*"cyGs2L*w c*n -e "ed+ced -y cond+ct)ng ,"edes)gn tests w)th the *ct+*l med)* to -e +sed to dete"m)ne the Je''ect)(eK hyd"*+l)c cond+ct)()ty +nde" (*")o+s 'low *nd hyd"*+l)c g"*d)ent cond)t)ons% *nd to ens+"e th*t l*m)n*" 'low cond)t)ons ,"e(*)l# These tests *"e "ecommended 'o" l*"ge2 sc*le ,"oBects *ndHo" 'o" "e,et)t)(e +se o' the s*me med)* on * n+m-e" o' sm*ll2sc*le ,"oBects# The test c*n +se * 'l+me o" t"o+gh o' "e*son*-le length ( N E m) *nd "e*son*-le c"oss sect)on*l *"e* (de,ends on s)5e o' med)* to -e tested% -+t gene"*lly 2 N 0#2 m )# The )nlet end o' the t"o+gh )s c*,*-le o' -e)ng "*)sed *-o(e the d*t+m to ,"od+ce the des)"ed test slo,e# The g"*(el )s cont*)ned w)th)n ,e"'o"*ted ,l*tes )n the t"o+gh% *nd m*nomete"s *"e )nst*lled *t *,,"o,")*te loc*t)ons to me*s+"e the he*d d)''e"ent)*l (dh) 'o" c*lc+l*t)on o' the hyd"*+l)c g"*d)ent (dhHdL)# Cle*n w*te" )s +sed )n the test% *nd the )n'low *dB+sted so th*t the g"*(el )s s*t+"*ted *t the he*d o' the 'l+me -+t w)th no s+"'*ce 'low# D+")ng8 the test the o+t'low (I) )s me*s+"ed w)th * sto, w*tch *nd * con(en)ently s)5ed cont*)ne"% *nd the de,th o' the wetted 5one (A) *t the ,e"'o"*ted o+t'low ,l*te )s me*s+"ed# .t )s ,oss)-le w)th these d*t* to then c*lc+l*te the Je''ect)(eK hyd"*+l)c cond+ct)()ty 'o" des)gn o' the system% *nd to c*lc+l*te the $eynolds n+m-e" to ens+"e l*m)n*" 'low cond)t)ons# .t )s -el)e(ed th*t the s+"'*ce 'low o-se"(ed on m*ny o' the o,e"*t)on*l !: systems )n the 3#!# )s the "es+lt o' *n )n*de;+*te hyd"*+l)c g"*d)ent ,"o()ded -y the systemGs des)gn *nd selected con')g+"*t)on (/=)# *ny o' the ,"o-lem systems )n the 3#!# h*(e -een const"+cted w)th * (e"y h)gh *s,ect "*t)o (L9W)% *nd w)tho+t *ny -ottom slo,e o" w*te" le(el cont"ols *t the o+tlet wo"ks# .n some c*ses% the o+tlet ,o"ts )n the e''l+ent m*n)'old we"e *t o" ne*" the to, o' the -ed% the"e-y neg*t)ng the de(elo,ment o' *ny s)gn)')c*nt hyd"*+l)c g"*d)ent )n the -ed *nd ens+")ng the occ+""ence o' s+"'*ce 'low '"om the -eg)nn)ng o' o,e"*t)ons# !ystems )n the 3#!# *nd# E+"o,e w)th s+ccess'+l hyd"*+l)c ,e"'o"m*nce ()#e#%9 m*)nten*nce o' s+-s+"'*ce 'low) do so w)th e)the" a slo,)ng -ottom *ndHo" *dB+st*-le o+tlet wo"ks wh)ch *llow the w*te" le(el to -e lowe"ed *t the end o' the -ed# A slo,ed -ottom o" lowe")ng the w*te" le(el *t the end o' the -ed then ,"od+ces the ,"ess+"e he*d "e;+)"ed to o(e"come "es)st*nce to 'low th"o+gh the med)* *nd the m*)nten*nce o' s+-s+"'*ce 'low cond)t)ons# An adDusta#le outlet 5rovides "reater fle8i#ilit and control and is t4e recommended a55roac4:

424

Ch*,te" 4

As5ect Ratio The *s,ect "*t)o (L9W) o' the wetl*nd -ed )s * (e"y )m,o"t*nt cons)de"*t)on )n the hyd"*+l)c des)gn o' !: wetl*nd systems% s)nce the m*4)m+m ,otent)*l hyd"*+l)c g"*d)ent )s "el*ted to the *(*)l*-le de,th o' the -ed d)()ded -y the length o' the 'low ,*th# *ny o' the e*"ly systems des)gned w)th *n *s,ect "*t)o o' /09/ o" mo"e *nd * tot*l de,th o' 0#E m (2 't) h*(e *n )n*de;+*te hyd"*+l)c g"*d)ent *nd s+"'*ce 'low )s )ne()t*-le# The hyd"*+l)c g"*d)ent (! '*cto" )n e;+*t)on 2) de')nes the tot*l he*d *(*)l*-le2)n the system to o(e"come the "es)st*nce to ho")5ont*l 'low )n the ,o"o+s# med)*# :o" e4*m,le% )n * !: -ed 200 m long *nd 0#E m dee,% )' the w*te" le(el )s *t the s+"'*ce o' the med)* *t the )n'l+ent end *nd ne*" the -ottom o' the -ed *t the e''l+ent end (w*te" de,th M 0#2 m)% the *(*)l*-le hyd"*+l)c g"*d)ent wo+ld -e 0#4mH200m o" 0#002# .' th)s wetl*nd -ed we"e /00 m w)de (L9W M 29/) *nd +sed = 2 a g"*(el med)* w)th * hyd"*+l)c cond+ct)()ty (ks) o' /0%000 m Hm Hd% the m*4)m+m = s+-s+"'*ce 'low% -*sed on e;+*t)on (2)% wo+ld -e 600 m Hd (0#2/ mgd)# 3s)ng the s*me (ol+me o' g"*(el )n * -ed 4<0 m long "es+lts )n * -ed w)dth o' *-o+t 4< m (L9W M /09/) *nd * hyd"*+l)c g"*d)ent o' 0#0000> the m*4)m+m s+-s+"'*ce 'low )n th)s = c*se wo+ld -e /E2 m Hd (0#04 mgd)% wh)ch )s 20 ,e"cent o' the 'low *llowed -y the = sho"te" -ed# .' the des)gn 'low we"e *ct+*lly 600 m Hd )n the second c*se% then s+"'*ce 'low on to, o' the -ed wo+ld -e +n*(o)d*-le% e(en tho+gh the -ed cont*)ns e4*ctly the s*me (ol+me o' med)*# 0ed Slo5e !: systems )n E+"o,e (20) h*(e -een const"+cted w)th +, to 6 ,e"cent slo,e 7owe(e"% )t on the -ottom o' the -ed to m*)nt*)n *n *cce,t*-le hyd"*+l)c g"*d)ent# )s not ,"*ct)c*l *nd ,"o-*-ly not ,oss)-le w)th !: systems to ,"ec)sely des)gn *nd const"+ct the -ed 'o" * s,ec)')c hyd"*+l)c g"*d)ent d+e to (*")*-)l)t)es )n the med)* +sed *nd )n const"+ct)on techn);+es% *nd the ,otent)*l 'o" longe" te"m ,*"t)*l clogg)ng# .n *dd)t)on% the const"+ct)on o' * -ed w)th * slo,)ng -ottom ,"o()des no 'le4)-)l)ty 'o" 8'+t+"e *dB+stments# G"e*te" 'le4)-)l)ty *nd cont"ol )s ,oss)-le w)th *n *dB+st*-le o+tletG wh)ch ,e"m)ts cont"ol o' the w*te" le(el o(e" the ent)"e des)gn de,th o' the -ed# .n th)s c*se% the -ottom o' the -ed co+ld -e 'l*t o" w)th * (e"y sl)ght slo,e to ens+"e d"*)n*ge% when "e;+)"ed# 7owe(e"% -ec*+se o' the hyd"*+l)c g"*d)ent "e;+)"ements% the *s,ect "*t)o (L9W) w)ll h*(e to -e "el*t)(ely low ()n the "*nge o' 0#49/ to =9. ) to ,"o()de the 'le4)-)l)ty *nd the "ese"(e c*,*c)ty 'o" '+t+"e o,e"*t)on*l *dB+stments#

42<

Ch*,te" 4 +edia ' 5es T*-le 4 ,"esents * s+mm*"y o' ty,)c*l ch*"*cte")st)cs 'o" the ty,es o' med)* wh)ch h*(e -een +sed )n !: const"+cted wetl*nds# Essent)*lly *ll o' the o,e"*t)on*l !: const"+cted wetl*nds )n the 3#!# h*(e +sed med)* "*ng)ng '"om med)+m g"*(el to co*"se "ock# The (*l+es )n T*-le 4 *"e )ntended *s ,"el)m)n*"y )n'o"m*t)on only# $ollo%in" selection of a media t 5e and siBeN t4e 4 draulic conductivit and 5orosit of t4e material s4ould #e determined in t4e field or la#orator 7 5rior to s stem desi"n7 The "ecent# t"end )n the G+l' !t*tes tow*"d the +se o' l*"ge" s)5es o' "ock )s -el)e(ed d+e to the )m,"ess)on c"e*ted -y the s+"'*ce 'low cond)t)ons on m*ny o' the e*"ly systems# .t w*s *,,*"ently tho+ght th*t the s+"'*ce 'low w*s c*+sed -y clogg)ng *nd th*t the +se o' * co*"se" "ock w)th l*"ge" (o)d s,*ces *nd * h)ghe" hyd"*+l)c cond+ct)()ty wo+ld o(e"come the ,"o-lem# .n most c*ses the ,"o-lem h*s not -een o(e"come s)nce the hyd"*+l)c g"*d)ent ,"o()ded )s too sm*ll# The +se o' sm*lle" "ock s)5es h*s * n+m-e" o' *d(*nt*ges )n th*t the"e )s mo"e s+"'*ce *"e* *(*)l*-le on the med)* 'o" t"e*tment% *nd the sm*lle" (o)d s,*ces *"e mo"e com,*t)-le w)th de(elo,ment o' the "oots *nd "h)5omes o' the (eget*t)on% *nd the 'low cond)t)ons sho+ld -e close" to l*m)n*"# When t+"-+lent 'low occ+"s )n the co*"se" med)* l)sted )n T*-le <% the Je''ect)(eK hyd"*+l)c cond+ct)()ty w)ll -e less th*n the (*l+es l)sted )n the t*-le#

T*-le <# Ty,)c*l

ed)* Ch*"*cte")st)cs 'o" !: Wetl*nds

n* Ty,e
E''ect)(e !)5e D /0 m m 2 6 /E =2 /26 &o"os)ty L =2 =< =6 40 4<

7yd"*+l)c Cond+ct)()ty = 2 m H m Hd /%000 <%000 F%<00 /0%000 /00%000

ks

Co*"se !*nd G"*(elly !*nd :)ne G"*(el ed)+m G"*(el Co*"se $ock

*# The ,o"os)ty )s +sed to dete"m)ne the *ct+*l 'low (eloc)ty )n the (o)d s,*ces% *nd )n e;+*t)ons (=) *nd &o"os)ty )s e;+*l to @o)d @ol+meHTot*l @ol+me% *nd )s (<) to dete"m)ne the s)5e o' the !: -ed# e4,"essed *s * ,e"cent# -# Ass+m)ng non2t+"-+lent% ne*" l*m)n*" 'low cond)t)ons% w)th cle*n# w*te"# m =H m 2Hd 4 24#E M g,dH't2#

42E

Ch*,te" 4

The hyd"*+l)c cond+ct)()ty (ks) (*l+es )n T*-le < *ss+me th*t the med)* *nd the w*te" 'low)ng th"o+gh )t *"e cle*n so th*t clogg)ng )s not * '*cto"# As d)sc+ssed )n * ,"e()o+s sect)on% some clogg)ng c*n occ+" )n these systems% es,ec)*lly ne*" the )nlet 5one whe"e most o' the s+s,ended sol)ds w)ll -e "emo(ed# As noted ,"e()o+sly% the o-se"(ed clogg)ng "e,"esented less th*n E ,e"cent o' the (o)d s,*ces )n the systems )n(est)g*ted# The m*Bo")ty o' the m*te")*l (O60L) w*s )no"g*n)c *nd -el)e(ed to -e the "es)d+e '"om const"+ct)on *ct)()t)es% *nd sho+ld not% the"e'o"e% h*(e * c+m+l*t)(e )m,*ct on hyd"*+l)c cond+ct)()ty# .t )s% howe(e"% necess*"y to ,"o()de * l*"ge s*'ety '*cto" *g*)nst these cont)ngenc)es *nd *do,t)on o' *n *,,"o*ch s)m)l*" to th*t +sed )t is t4erefore )n the des)gn o' l*nd t"e*tment systems (=0) )s ,"o,osed# recommended t4at a value E !!3 of t4e JeffectiveK 4 draulic conductivit <Cs@ #e used for desi"n: '4e initial desi"n7 for t4e same reasons7 s4ould not utiliBe more t4an >0 5ercent of t4e 5otential 4 draulic "radient availa#le in t4e 5ro5osed #ed: '4ese t%o limits7 com#ined %it4 an adDusta#le outlet for t4e #ed disc4ar"e s4ould ensure a more t4an ade;uate safet factor in t4e 4 draulic desi"n of t4e s stem: These two l)m)ts w)ll *lso h*(e the ,"*ct)c*l e''ect o' l)m)t)ng the *s,ect "*t)o o' the -ed to N =9/ 'o" 0#E m (2 't) dee, -eds *nd to *-o+t 0#F<9/ 'o" 0#= m (/ 't) dee, -eds# 3s)ng s+ch * low (*l+e 'o" hyd"*+l)c g"*d)ent w)ll hel, m*)nt*)n ne*" l*m)n*" 'low )n the -ed *nd '+"the" (*l)d*te the +se o' D*"cyGs L*w 'o" des)gn o' these systems# !)nce th)s *,,"o*ch ens+"es * "el*t)(ely w)de ent"y 5one% )t w)ll *lso "es+lt )n * low o"g*n)c lo*d)ng on the c"oss sect)on*l *"e* *nd the"e-y "ed+ce conce"ns o(e" clogg)ng# .n *dd)t)on to the )nte"n*l hyd"*+l)c conce"ns d)sc+ssed *-o(e% )t )s necess*"y to h*(e *de;+*te )nlet *nd o+tlet st"+ct+"es 'o" the -ed to *ss+"e ,"o,e" d)st")-+t)on *nd collect)on o' 'low *nd m*4)m+m +t)l)5*t)on o' the med)* ,"o()ded )n the -ed# )nlet Structures The )nlet de()ces *t o,e"*t)on*l systems )ncl+de s+"'*ce *nd s+-s+"'*ce m*n)'olds% *n o,en t"ench ,e",end)c+l*" to the 'low d)"ect)on% *nd s)m,le% s)ngle ,o)nt we)" -o4es# The m*n)'old des)gns )ncl+de * (*")ety o' 'e*t+"es# .n some c*ses ,e"'o"*ted ,),e )s +sed 'o" -oth s+"'*ce *nd s+-s+"'*ce )nst*ll*t)ons# .n one c*se the s+-s+"'*ce2 m*n)'old +t)l)5ed two to th"ee (*l(ed o+tlets )n the cell# A s+"'*ce m*n)'old de(elo,ed -y T@A +ses m+lt),le% *dB+st*-le o+tlet ,o"ts (=/%=2)# Th)s *llows the o,e"*to" to m*ke *dB+stments 'o" d)''e"ent)*l settlement o' the ,),e *nd to m*)nt*)n +n)'o"m d)st")-+t)on o' the w*stew*te"# The ,"o,onents o' s+-s+"'*ce )nlet m*n)'olds cl*)m they *"e necess*"y to *(o)d the -+)ld2+, o' *lg*l sl)mes on the "ock s+"'*ces *nd "es+lt)ng clogg)ng *dB*cent to * s+"'*ce m*n)'old# The d)s*d(*nt*ges o' * s+-s+"'*ce m*n)'old *"e the )n*-)l)ty 'o" '+t+"e *dB+stment *nd the l)m)ted *ccess 'o"

42F

Ch*,te" 4 m*)nten*nce# .n one c*se% * -+")ed m*n)'old -ec*me clogged w)th t+"tles (ente"ed the ,),)ng system '"om the ,"el)m)n*"y t"e*tment l*goon) *nd h*d to -e "emo(ed# A surface manifold7 %it4 adDusta#le outlets7 seems to 5rovide t4e ma8imum fle8i#ilit for future adDustments and maintenance and is recommended: 3se o' * co*"se "ock (6 to /< cm P= 2 EKQ) )n th)s ent"y 5one% co+,led w)th *n *de;+*te hyd"*+l)c g"*d)ent 'o" the -ed% sho+ld ens+"e "*,)d )n')lt"*t)on *nd ,"e(ent ,ond)ng *nd *lg*e de(elo,ment# .n cont)n+o+sly w*"m *nd s+nny cl)m*tes% sh*d)ng o' th)s ent"y 5one w)th e)the" (eget*t)on o" * st"+ct+"e m*y *lso -e necess*"y# .n cold w)nte" cl)m*tes% some the"m*l ,"otect)on 'o" *n *-o(e2s+"'*ce m*n)'old w)ll ,"o-*-ly -e necess*"y# Outlet Structures O+tlet st"+ct+"es )n +se *t o,e"*t)on*l !: wetl*nd systems )ncl+de s+-s+"'*ce m*n)'olds% *nd we)" -o4es o" s)m)l*" g*ted st"+ct+"es# The ,e"'o"*ted s+-s+"'*ce m*n)'old )s the most commonly +sed de()ce> howe(e"% the loc*t)on o' th*t m*n)'old )n the -ed h*s (*")ed cons)de"*-ly# .n * 'ew c*ses )t h*s -een loc*ted )n * sh*llow t"ench% -elow the -ottom o' the -ed% ,e"m)tt)ng com,lete d"*)n*ge o' the -ed *nd de(elo,ment o' the m*4)m+m hyd"*+l)c g"*d)ent 'o" the system# .n m*ny c*ses% the m*n)'old *ndHo" the o+tlet ,o"ts h*(e -een loc*ted *-o(e the -ottom o' the -ed% *nd )n some c*ses the o+tlet ,o"ts h*(e -een )oc*ted ne*" the to, o' the -ed# As )nd)c*ted ,"e()o+sly% th)s l*tte" ,"*ct)ce "es+lts )n s+"'*ce 'low on the -ed# .n most c*ses% the s+-s+"'*ce o+tlet m*n)'old connects d)"ectly to the ')n*l d)sch*"ge ,),e% *ndHo" to * conc"ete ch*nnel +sed 'o" ')n*l d)s)n'ect)on# !ome system des)gns )n E+"o,e *nd those )n the 3#!# de")(ed '"om th*t ,"*ct)ce (=/%=2)% connect the s+-s+"'*ce m*n)'old to *n *dB+st*-le o+tlet 'o" w*te" le(el cont"ol# :low then ,"oceeds to e)the" d)sch*"ge o" d)s)n'ect)on# The +se o' *n *dB+st*-le o+tlet w*s ,"e()o+sly "ecommended to m*)nt*)n *n Th)s de()ce c*n *lso h*(e s)gn)')c*nt% *de;+*te hyd"*+l)c g"*d)ent )n the -ed# The s+"'*ce o' the -ed c*n -e 'looded to o,e"*t)on*l *nd m*)nten*nce -ene')ts# enco+"*ge% de(elo,ment o' newly ,l*nted (eget*t)on *nd to s+,,"ess +ndes)"*-le weeds% *nd the w*te" le(el c*n -e lowe"ed )n *nt)c),*t)on o' m*Bo" sto"m e(ents *nd to ,"o()de *dd)t)on*l the"m*l ,"otect)on *g*)nst '"ee5)ng d+")ng w)nte" o,e"*t)ons )n cold cl)m*tes# '4e +se of a 5erforated su#surface manifold connected-to an adDusta#le outlet %ould seem to offer t4e ma8imum fle8i#ilit and relia#ilit as t4e outlet device for S$ wetl*nd systems# !)nce the m*n)'old )s -+")ed *nd )n*ccess)-le 'ollow)ng

426

Ch*,te" 4

const"+ct)on% c*"e'+l g"*d)ng *nd s+--*se com,*ct)on wo+ld -e "e;+)"ed d+")ng const"+ct)on *nd cle*n2o+t ")se"s sho+ld -e ,"o()ded )n the l)ne# 0O. 6 RE+O*A/ W4en 5rocess Cinetics %ere "iven an consideration7 most of t4e e8istin" s stems in t4e U:S: and: Euro5e %ere desi"ned as an attac4ed "ro%t4 #iolo"ical reactor usin" a first order 5lu" flo% model7 s4o%n 5reviousl as e;uation <!@A

(/)
The e''l+ent 1OD< (C%) )n e;+*t)on / )s% *s ,"e()o+sly d)sc+ssed% )n'l+enced -y the ,"od+ct)on o' "es)d+*l 1OD < w)th)n the wetl*nd '"om decom,os)t)on o' ,l*nt det")t+s *nd othe" n*t+"*lly occ+"")ng o"g*n)cs# Th)s "es)d+*l 1OD< )s ty,)c*lly )n the "*nge o' 2 to F mgHL# As a result7 e;uation <!@ s4ould not #e used for desi"ns for a final 0O.6 E 6 m"F/: .t h*s -een *"g+ed th*t ,l+g 'low k)net)cs do not *,,ly to !: const"+cted wetl*nd systems -ec*+se the dye *nd t"*ce" st+d)es wh)ch h*(e -een ,e"'o"med do not e4h)-)t the )de*l ,l+g 'low "es,onse# :)g+"e /= ,"esents the "es+lts o' * t"*ce" st+dy% +s)ng l)th)+m chlo")de (*n )no"g*n)c% conse"(*t)(e t"*ce")% cond+cted )n /060 *t the o,e"*t)on*l !: wetl*nd system *t C*"()lle% LA (2F)# Essent)*lly /00 ,e"cent o' the t"*ce" w*s *cco+nted 'o" )n the e''l+ent% so th)s c*n -e cons)de"ed * (*l)d st+dy# .t cle*"ly d)d not e4h)-)t )de*l ,l+g 'low "es,onses% -+t the c+"(e )s m+ch close" to ,l+g 'low cond)t)ons th*n to the com,lete m)4 *lte"n*t)(e# The cent"o)d o' the c+"(e )nd)c*tes *n 7$T o' 46 ho+"s% wh)ch )s )dent)c*l to the theo"et)c*l detent)on t)me c*lc+l*ted w)th the *ct+*l 'low% me*s+"ed ,o"os)ty% *nd wetl*nd cell d)mens)ons# D*t* '"om s)m)l*" tests *t othe" s)tes The"e w*s no s+"'*ce 'low d+")ng th)s test# show *n e(en close" "esem-l*nce to ,l+g 'low#

The sh*,e o' the c+"(e on :)g+"e /= )s s)m)l*" to those o-se"(ed w)th '*c+lt*t)(e ,onds *nd s)m)l*" w*stew*te" t"e*tment conce,ts whe"e ,l+g 'low cond)t)ons *"e *lso *ss+med *s the -*s)s 'o" des)gn (==)# odels *"e *(*)l*-le 'o" these systems wh)ch *ttem,t to de')ne cond)t)ons -etween ,l+g 'low *nd com,lete

420

Ch*,te" 4 m)4% -+t the d)'')c+lty )n de')n)ng the necess*"y ,*"*mete"s h*s "es+lted )n m)n)m*l +se o' these *lte"n*t)(es#

:)g+"e /=# L)th)+m T"*ce" !t+dy% C*"()lle> LA#

The ,l+g 'low model )s ,"esently )n gene"*l +se# *nd )t seems to ,"o()de * "e*son*-le *,,"o4)m*t)on o' ,e"'o"m*nce )n these !: const"+cted wetl*nds# 7owe(e"% mo"e so,h)st)c*ted models h*(e *lso -een ,"o,osed 'o" !: wetl*nds# One model )ncl+des * ,l+g 'low segment 'ollowed -y th"ee cont)n+o+sly st)""ed (com,lete m)4) "e*cto"s )n se")es (4=)# When s+'')c)ent d*t* *"e *(*)l*-le to (*l)d*te these *lte"n*t)(e models% they m*y "e,l*ce the c+""ent *,,"o*ch# )n t4e interim7 t4e use of t4e 5lu" flo% model is recommended for desi"n: The JtK o" hyd"*+l)c "es)dence t)me (7$T) '*cto" )n e;+*t)on (/) c*n -e de')ned *s9

<3@

42/0

Ch*,te" 4

Whe"e9

n L W d I

M e''ect)(e ,o"os)ty o' med)* (see T*-le <) L *s * dec)m*l M length o' -ed% m ('t) M w)dth o' -ed% m ('t) M *(e"*ge de,th o' l);+)d )n -ed% m ('t) = = M *(e"*ge 'low th"o+gh the -ed% m Hd ('t Hd)

The I (*l+e )n e;+*t)on (=) )s the *(e"*ge 'low )n the -ed to *cco+nt 'o" ,"ec),)t*t)on% see,*ge% e(*,ot"*ns,)"*t)on *nd othe" g*)ns *nd losses o' w*te" d+")ng t"*ns)t o' the -ed# Th)s )s the s*me (*l+e +sed )n D*"cyGs L*w 'o" hyd"*+l)c des)gn# &+-l)shed (*l+es *"e +s+*lly *(*)l*-le 'o" *n est)m*te o' ,"ec),)t*t)on *nd ET losses *t * ,*"t)c+l*" s)te# The d (*l+e )n e;+*t)on (=) )s the *(e"*ge de,th o' l);+)d )n the -ed# .'% *s "ecommended ,"e()o+sly% the des)gn hyd"*+l)c g"*d)ent )s l)m)ted to /0 ,e"cent o' the ,otent)*l *(*)l*-le% 2then the *(e"*ge de,th o' w*te" )n the -ed w)ll -e# e;+*l to 0< ,e"cent o' the tot*l de,th o' the t"e*tment med)* )n the -ed# The tem,e"*t+"e de,endence o' the "*te const*nt )n e;+*t)on (/) )s de')ned *s9

(4) Whe"e9

Com-)n)ng e;+*t)ons (/)% (=)% *nd (4) ,"od+ces9

(<)

4 2 //

Ch*,te" 4 !)nce the te"m LW )n e;+*t)on (<) )s e;+*l to the s+"'*ce *"e* o' the -ed% "e*""*ngement o' te"ms )n e;+*t)on (<) ,e"m)ts the c*lc+l*t)on o' the s+"'*ce *"e* (A%) "e;+)"ed to *ch)e(e the necess*"y le(el o' 1OD< "emo(*l9

Whe"e9

As

M -ed s+"'*ce *"e*% m ('t )

Othe" te"ms de')ned ,"e()o+sly

The de,th o' med)* selected w)ll de,end on the des)gn )ntent)ons 'o" the system# .' the (eget*t)on )s )ntended *s * m*Bo" o4ygen so+"ce 'o" n)t")')c*t)on )n the system% then the de,th o' the -ed sho+ld not e4ceed the ,otent)*l "oot ,enet"*t)on de,th 'o" the ,l*nt s,ec)es to -e +sed# Th)s w)ll ens+"e *(*)l*-)l)ty o' some o4ygen th"o+gho+t the -ed ,"o')le% -+t m*y "e;+)"e m*n*gement ,"*ct)ces wh)ch *ss+"e "oot ,enet"*t)on to these de,ths# T*-le E ,"esents "es+lts '"om the ,)lot system )n !*ntee% CA (4) show)ng the "el*t)onsh), -etween "oot ,enet"*t)on *nd ,e"'o"m*nce# The "oot de,ths shown )n T*-le E *"e cons)de"ed to -e ne*" the m*4)m+m ,"*ct)c*l l)m)t to -e e4,ected# The des)gn *,,"o*ch )n E+"o,e h*s *lso *ss+med * m*4)m+m de,th o' 0#E m 'o" Phragmites (/<)#

T*-le E# &e"'o"m*nce o' @eget*ted *nd 3n(eget*ted !: Wetl*nd 1eds (4) 1ed Ty,e 1+l"+sh% Scirpus $eeds% Phragmites C*tt*)ls% Typha No @eget*t)on $oot De,th% m 0#6 0#E 0#= 0#0 :)n*l E''l+ent I+*l)ty% m;HL T!! 1OD < < 22 =0 =E 4 6 E E
*

N7

2 < /6
22

*# &")m*"y e''l+ent )n,+t (1OD< M //6 mgHL% !! M <F mgHL% N7= M 2< mgHL)

The"e )s one o,e"*t)on*l system )n the 3#!# ( onte"ey% @A) w)th * med)* de,th o' 0#0 m (= 't)> the most commonly +sed de,th )s 0#E m (2 't)# One system (1e*"

4 2 /2

Ch*,te" 4

C"eek% AL) +s)ng Typha )n ')ne g"*(el )s o-t*)n)ng e4cellent ,e"'o"m*nce w)th * de,th o' 0#= m% wh)ch m*tches the "oot ,enet"*t)on l)sted )n T*-le E 'o" th*t ,l*nt# '4e final desi"n and siBin" of t4e S$ #ed for 0O. 6 removal is an iterative 5rocessA !: .etermine t4e media t 5e7 ve"etation7 and de5t4 of #ed to #e used: 2: .etermine # field or la#orator testin" t4e 5orosit <n@ and JeffectiveK 4 draulic conductivit <Cs@ of t4e media to #e used: 3: .etermine t4e re;uired surface area of t4e #ed7 for t4e desired level of 0O.6 removal7 %it4 e;uation =: ?: .e5endin" on site to5o"ra54 7 select a 5reliminar as5ect ratio </AW@N 0:?A! u5 to 3A ! are "enerall acce5ta#le: 6: .etermine #ed len"t4 </@ and %idt4 <W@ from t4e 5reviousl assumed as5ect ratio7 and results of ste5 2: =: Usin" .arc Hs /a% <e;uation 2@ %it4 t4e 5reviousl recommended limits <Cs E !F3 JeffectiveK value7 4 draulic "radient S E !0O of ma8imum 5otential@7 determine t4e flo% <I@ %4ic4 can 5ass t4rou"4 t4e #ed in a su#surface mode: )f t4is I is less t4an t4e actual desi"n flo%7 t4en surface flo% is 5ossi#le: )n t4at case it is necessar to adDust t4e / and W values until t4e .arc Hs I is e;ual to t4e desi"n flo%: >: )t is not valid to use e;uation 6 %it4 effluent 0O. 6 <&e@ values #elo% 6 m"Fl: AS 5reviousl discussed7 t4ese %etland s stems e85ort a 0O.6 residual due to decom5osition of t4e natural or"anic detritus in t4e s stem: 8: )n cold climates it is necessar to assume a desi"n tem5erature for 0O. 6 to first determine t4e re;uired surface area: '4ermal calculations are t4en necessar to determine t4e %inter 4eat losses and #ed tem5erature conditions durin" t4e desi"n 2R': $urt4er iterations of t4is 5rocedure are necessar until t4e assumed tem5erature and t4e tem5erature determined # t4e 4eat loss calculations conver"e:

4 2 /=

Ch*,te" 4 Sus5ended Solids Removal A k)net)c model )s not *(*)l*-le 'o" s+s,ended sol)ds "emo(*l> -*sed on the d*t* ,"esent*t)ons )n :)g+"es < *nd E% )t )s +nl)kely th*t s+ch * model w)ll -e de(elo,ed# .t wo+ld *,,e*" th*t w)th *n 7$T o' *-o+t / d the T!! w)ll -e "emo(ed to * le(el o' *-o+t !0 mgHL# As a rule of t4um# it can #e assumed t4at if t4e system is des)gned for a certain level of 0O.6 removal7 t4e 'SS removal %ill #e com5ara#le as lon" as si"nificant lon"-term surface flo% does not occur: Long2te"m s+"'*ce 'low c*n "es+lt )n sho"t c)"c+)t)ng *nd the *dd)t)on o' T!! to the s+"'*ce 'low st"e*m )n the 'o"m o' *lg*e *nd ,l*nt det")t+s#

-)'RO1E- RE+O*A/ As )nd)c*ted )n the d)sc+ss)on "el*ted to :)g+"es 6 *nd 0% the m*Bo" ,*thw*y 'o" n)t"ogen "emo(*l )n !: wetl*nd systems )s -)olog)c*l n)t")')c*t)on 'ollowed -y den)t")')c*t)on (4%F%6)# 1*sed on the d*t* ,"esent*t)ons )n :)g+"es 6 *nd 0% )t )s cle*" th*t *mmon)* "emo(*l )s not (e"y e''ect)(e )n most o' the o,e"*t)on*l !: systems st+d)ed# The l)m)t)ng '*cto" )n *mmon)* "emo(*l ()* n)t")')c*t)on )s -el)e(ed to -e the *(*)l*-)l)ty o' o4ygen )n the med)* ,"o')le# Th)s const"*)nt )s *,,*"ent "eg*"dless o' the *ge o" o,e"*t)on*l h)sto"y o' the system# The only two systems demonst"*t)ng e4cellent *mmon)* "emo(*l )n :)g+"e 0 h*(e ,l*nt "oots (*nd the"e'o"e *(*)l*-le o4ygen) th"o+gho+t the ,"o')le% *nd s+'')c)ent 7$T to com,lete the "e*ct)ons# The m*Bo")ty o' the systems const"+cted )n the G+l' !t*tes )n "ecent ye*"s h*(e too -")e' *n 7$T ( N 2d) *nd )n*de;+*te "oot ,enet"*t)on *nd de(elo,ment to de,end on the ,l*nt "oots *s *n o4ygen so+"ce 'o" s)gn)')c*nt n)t")')c*t)on# .n these c*ses% othe" o4ygen so+"ces w)ll -e necess*"y# The"e )s no consens+s on how m+ch o4ygen c*n -e '+"n)shed -y the (eget*t)on )n !: wetl*nds o" on the o4ygen t"*ns'e" e'')c)ency o' (*")o+s ,l*nt s,ec)es# The"e )s consens+s th*t these eme"gent *;+*t)c ,l*nts t"*nsm)t eno+gh o4ygen to the)" "oots to kee, *l)(e# The d)s*g"eement occ+"s o(e" how m+ch e4cess o4ygen )s then *(*)l*-le to s+,,o"t -)olog)c*l *ct)()ty )n the "oot 5one# &+-l)shed est)m*tes h*(e 2 "*nged '"om 5e"o to 4< gm 02H m Hd o' wetl*nd s+"'*ce *"e* (4%F%=4)# Th)s o4ygen )s not -el)e(ed to -e d)''+sed th"o+gho+t the s+-s+"'*ce ,"o')le% -+t )s l)kely to -e *(*)l*-le2only on the s+"'*ces o' the sm*lle" "oots% w)th)n the "oot 5one% )n the -ed# These *e"o-)c m)c"os)tes on the "oot h*)"s ,"o()de ,otent)*l cont*ct s+"'*ces 'o" the n)t")')c*t)on o' *mmon)*# These m)c"os)tes ,"o-*-ly occ+" th"o+gho+t the length o' the -ed% -+t the o4ygen dem*nd 'o" 1OD< "emo(*l )s l)kely to l)m)t the ,otent)*l 'o" n)t")')c*t)on )n the '"ont ,*"t o' the system#

42/4

Ch*,te" 4

An alternative o8 "en source7 ot4er t4an t4e 5lant roots7 is not a55arent in t4e com5letel su#mer"ed7 #ut full rooted7 S$ #ed: !)nce these systems% *s shown )n T*-le E% do ,"o()de s)gn)')c*nt *mmon)* "emo(*l (wh)ch )s co""el*ted to "oot de,th)% )t seems l)kely th*t the"e )s some o4ygen *(*)l*-le on the s+"'*ces o' the ,l*nt "oots# !)nce )t t*kes *-o+t < mg o' o4ygen to con(e"t / mg o' *mmon)* to n)t"*te% )t )s ,oss)-le to est)m*te the o4ygen th*t w*s ,"o()ded )n the !*ntee system to *ch)e(e the "emo(*ls shown )n T*-le E# These "es+lts *"e s+mm*")5ed )n T*-le F# The (*l+es )n T*-le F do not de')ne the *ct+*l o4ygen ,"od+ct)on o' the ,l*nts% -+t only )nd)c*te the *mo+nt o' o4ygen necess*"y to *cco+nt 'o" the known "emo(*l o' *mmon)* *t the !*ntee ,"oBect# .t seems l)kely th*t the ,l*nt "oots we"e the so+"ce o' th)s o4ygen s)nce no othe" so+"ce )s *,,*"ent no" )s *ny othe" *lte"n*t)(e *mmon)* "emo(*l ,"ocess l)kely# These (*l+es '"om !*ntee *"e *lso cons)stent w)th the ,e"'o"m*nce o' the 1e*" C"eek system (see :)g+"e 0 *nd "el*ted d)sc+ss)on)# The = *(e"*ge (*l+e o' F#< gm 02Hm Hd )s *lso cons)stent w)th% *nd ne*" the low end o'% the "*nge "e,o"ted -y E+"o,e*n )n(est)g*to"s (F%=4/#

T*-le F# &otent)*l O4ygen '"om @eget*t)on *t !*ntee% CA

&l*nt Ty,e

$oot De,th m 0#FE 0#E0 0#=0

A(*)l*-le O4ygen = * 2 gmHm Hd gmHm Hd F#< 6#0 F#0 F#< <#F 4#6 2#/

1+l"+sh "+sh (Scirpus) $eeds (Phragmites) C*tt*)ls (Typhal A(e"*ge

A(*)l*-le o4ygen ,e" +n)t (ol+me o' *ct+*l "oot 5one# A(*)l*-le o4ygen ,e" +n)t s+"'*ce *"e* o' 0#FE m dee, wetl*nd -ed#

The e4*m,le -elow )ll+st"*tes the *,,l)c*t)on o' these tent*t)(e "el*t)onsh),s9 Ass+me9 I M =F6 m =Hd% N7% )n M 20 mgHL% N7% o+t M 2 mgHL &l*nt ty,e9 c*tt*)ls% 1ed de,th M 0#= m = A(e"*ge *(*)l*-le o4ygen F#< gmHm Hd ('"om T*-le E) 1 O D< )n M F< mgHL% 1OD< le(el 'o" st*"t o' n)t")')c*t)on M 20 mgHL ed)* ,o"os)ty M 0#4

4 2 /<

Ch*,te" 4

(e;+*t)on =) 7$T 'o" 1OD< M ln(F<H20)H/#/04 M /#2 d A"e* 'o" 1OD< "emo(*l to 20 mgHL M 0#4 h* (e;+*t)on E) N)t")')c*t)on9 O4ygen *(*)l*-le M (0#= m)(F#< gmHm =Hd) M 2#2< gmHm2H d O4ygen "e;+)"ed M (20 2 2)(=F6)(<) M =4%0E< gmHd N)t")')c*t)on *"e* "e;+)"ed M (=4%0E<)H(2#2<) M /<%/40 m M /#< h* Tot*l 7$T M /#2 R 4#6 M E#0 d Tot*l A"e* M 0#4 R /#< M / #0 h* (4#F *c) (4F *cHmgd) The e4*m,le ,"es+mes * two2st*ge system )n wh)ch the 1OD< )s "ed+ced to *-o+t 20 mgHL 'ollowed -y n)t")')c*t)on w)th o4ygen s+,,l)ed -y the (eget*t)on# The "em*)n)ng 1OD< )n th)s second st*ge wo+ld -e *(*)l*-le 'o" den)t")')c*t)on *nd the ')n*l e''l+ent 1OD< sho+ld -e *t -*ckg"o+nd le(els 'o" these systems# The "es+lts o' th)s e4*m,le *"e cons)stent w)th the !*ntee ,e"'o"m*nce *nd othe" loc*t)ons whe"e ,l*nt s+,,l)ed o4ygen )s -el)e(ed to -e "es,ons)-le 'o" n)t")')c*t)on# '4is su""ests t4at nitrification via t4is 5at4%a is 5ossi#le %4en #ot4 full develo5ed root s stems and sufficient detention time are availa#le: The l)m)t)ng '*cto" )n th)s c*se )s the "*te *t wh)ch the ,l*nt c*n ,"o()de o4ygen# 2o%ever7 t4ere: are7 at 5resent7 limited inde5endent data to su55ort t4is tentative 5rocedure derived from t4e e85erience at Santee7 %4ic4 s4ould #e used %it4 caution for desi"n until furt4er researc4 results are availa#le: )t %ill also #e necessar to identif t4e seasonal and tem5erature influences on t4e 5rocedure to ac4ieve successful a55lication in cold climates: Ado,t)on o' th)s *,,"o*ch 'o" n)t")')c*t)on wo+ld then "e;+)"e *t le*st * s)42d*y 7$T% *nd the cost o' the "ock o" g"*(el med)* co+ld -e ,"oh)-)t)(e# Alte"n*t)(e# methods 'o" o4ygen s+,,ly *nd n)t")')c*t)on% the"e'o"e% dese"(e cons)de"*t)on# These *lte"n*t)(e methods m*y )ncl+de9 mech*n)c*l *e"*t)on *'te" 1OD < "ed+ct)on% ,"o()s)on o' o,en w*te" 5ones 'o" s+"'*ce "e*e"*t)on% +se o' the o(e"l*nd 'low l*nd t"e*tment conce,t 'o" n)t")')c*t)on% *nd the +se o' ,*"*llel n)t")')c*t)on cells o,e"*ted on * -*tch ty,e ')ll *nd d"*w -*s)s to "et+"n *tmos,he")c o4ygen to the med)* ,"o')le# Anothe" *,,"o*ch% wh)ch )s +nde" const"+ct)on 'o" -oth :W! *nd !: cells )n Kent+cky% w)ll s+,e")m,ose * (e"t)c*l 'low% "ec)"c+l*t)ng -ed% com,osed o' ')ne .n th)s c*se the "ec)"c+l*t)ng g"*(el% 'o" n)t")')c*t)on on to, o' the e4)st)ng system# ')lte" w)ll -e loc*ted *t the )n'l+ent end o' the -ed# The e''l+ent '"om the n)t")')c*t)on
2

42/E

Ch*,te" 4 -ed w)ll m)4 w)th the no"m*l +nt"e*ted 'low )n the wetl*nd cell whe"e the n)t"*tes ,"od+ced sho+ld -e den)t")')ed# W)th th)s *,,"o*ch the wetl*nd cell need only -e s)5ed 'o" 1OD< "emo(*l "e;+)"ements s)nce n)t")')c*t)on )s e4,ected to occ+" )n the The conce,t o''e"s ,"om)se 'o" "et"o')t o' the m*ny e4)st)ng "ec)"c+l*t)ng -ed# systems wh)ch *"e h*()ng d)'')c+lty meet)ng the)" d)sch*"ge l)m)ts 'o" *mmon)*# The conce,tG m*y *lso -e mo"e cost2e''ect)(e th*n * m)n)m+m o' * s)42d*y 7$T 'o" wetl*nds whe"e ,l*nt2*(*)l*-le o4ygen )s *ss+med *s the sole so+"ce 'o" n)t")')c*t)on# The hyd"*+l)c des)gn o' s+ch * system w)ll h*(e to )ncl+de cons)de"*t)on o' the "ecycle 'low w)th)n the ho")5ont*l ,o"t)on o' the -ed# D*t* collect)on )s ,l*nned 'o" * /22 month ,e")od *t the Kent+cky s)te *nd sho+ld le*d to o,t)m)5*t)on o' the conce,t 'o" *,,l)c*t)on elsewhe"e# Th"ee othe" des)gn models 'o" est)m*t)ng *mmon)* "emo(*l )n const"+cted wetl*nd systems *"e *(*)l*-le )n the l)te"*t+"e# The W&C: *n+*l o' &"*ct)ce (6) ,"esents * model 'o" *mmon)* "emo(*l -*sed on * "eg"ess)on *n*lys)s o' -oth :W! *nd !: systems% 'o" *nn+*l *(e"*ge cond)t)ons w)th no ,"o()s)on 'o" tem,e"*t+"e co""ect)on9

N 7e N 70 I

wetl*nd s+"'*ce *"e* "e;+)"ed 'o" *mmon)* "emo(*l% h* M e''l+ent *mmon)*% mgHL M )n'l+ent *mmon)*% mgHL = M J*(e"*geK 'low th"o+gh system% m Hd

1*sed on ,)lot sc*le wo"k w)th !: wetl*nds% 1*(o" (/2) h*s ,"esented the 'ollow)ng e;+*t)on 'o" *mmon)* "emo(*l )n those systems9

(F)

42/F

Ch*,te" 4

Whe"e9

As

M "e;+)"ed s+"'*ce *"e*% m de,endent "*te const*nt% d

2/

d n I

M M

*(e"*ge de,th o' l);+)d )n the -ed% m e''ect)(e ,o"os)ty o' -ed med)*% L *s * dec)m*l#
=

M *(e"*ge 'low th"o+gh the system% m H d

1*sed on * "eg"ess)on *n*lys)s o' * l)m)ted n+m-e" o' systems% 7*mme" *nd Kn)ght (4/) h*(e ,"o,osed the 'ollow)ng e;+*t)on 'o" *mmon)* "emo(*l )n const"+cted wetl*nd systems9
A = ( 0 . 0 0 1 8 3 1 ) ( N Ho ) ( Q ) N Ho + 0 . 1 6 0 6 3

Whe"e9

As N7 0 N7e I

M "e;+)"ed wetl*nd s+"'*ce *"e*% h* M ln'l+ent *mmon)* concent"*t)on% mgHL M des)"ed e''l+ent *mmon)* concent"*t)on% mgHL = M *(e"*ge 'low th"o+gh the system% m H d

E;+*t)ons E% F% *nd 6 ,"od+ce com,*"*t)(e "es+lts down to *n *mmon)* e''l+ent concent"*t)on o' *-o+t 2 mgHL# 7owe(e"% *ll th"ee e;+*t)ons w)ll ,"ed)ct * tot*l t"e*tment *"e* *t le*st tw)ce th*t "es+lt)ng '"om the )n)t)*l ,"oced+"e ,"esented% wh)ch de,ends on the o4ygen ,"od+ced -y the (eget*t)on# The tot*l 7$T 'o" the )n)t)*l e4*m,le w*s s)4 d*ys> the 7$T 'o" the s*me cond)t)ons% +s)ng e;+*t)ons E% F% *nd 6% "*nges '"om /= to /0 d*ys# Th)s m*y -e -ec*+se *ll th"ee ,"oced+"es we"e de")(ed '"om s)te cond)t)ons whe"e o4ygen m*y h*(e -een sl)ghtly to s)gn)')c*ntly de')c)ent )n the w*te" 'low)ng th"o+gh the system# None o' these e;+*t)ons w)ll ,"o()de *n *cc+"*te ,"ed)ct)on o' *mmon)* "emo(*l 'o" the !: systems shown on :)g+"es 6 *nd 0# Th)s )s -el)e(ed to -e d+e to the *lmost com,lete l*ck o' o4ygen )n most o' the systems *nd% con(e"sely% to the ,"esence o' *(*)l*-le o4ygen )n the two systems wh)ch demonst"*ted e4cellent *mmon)* "emo(*l E;+*t)ons E% F% *nd 6 m*y ,"o()de * "e*son*-le o"de"2o'2m*gn)t+de est)m*te o' *mmon)* "emo(*l ,e"'o"m*nce

? - !8

Ch*,te" 4 o' m*ny o' the e4)st)ng !: const"+cted wetl*nds wh)ch do not h*(e s+'')c)ent o4ygen '"om the ,l*nts o" othe" so+"ces#

*E1E'A')O- SE/E&')O- A-. +A-A1E+E-' ost o' the const"+cted wetl*nds )n the 3#! +t)l)5e one o" mo"e o' the ,l*nt s,ec)es l)sted )n T*-les E *nd F# A-o+t 40 ,e"cent o' the o,e"*t)on*l !: systems +se only Scripus. Phragmites )s the most w)dely +sed s,ec)es )n the E+"o,e*n systems# A n+m-e" o' systems )n the G+l' !t*tes *lso +sed * n+m-e" o' 'lowe")ng ,l*nts 'o" *esthet)c "e*sons# These so't t)ss+e ,l*nts decom,ose (e"y "*,)dly *nd c*n *''ect w*te" ;+*l)ty )n the e''l+ent# *ny loc*t)ons *do,ted * "o+t)ne '*ll h*"(est to "emo(e these ,l*nts -e'o"e they d)ed o" s+''e"ed '"ost d*m*ge# The"e h*(e -een some *ttem,ts to c"e*te * ,l*nt d)(e"s)ty s)m)l*" to th*t ,"esent )n * n*t+"*l m*"sh> th)s *,,"o*ch )s mo"e e4,ens)(e *nd the )ntended d)(e"s)ty c*n -e d)'')c+lt to m*)nt*)n# An of t4e t4ree s5ecies listed in 'a#les = and > are suita#le for use in S$ s stems: .' the ,l*nt )s e4,ected to ,"o()de * s)gn)')c*nt t"e*tment '+nct)on% then the de,th o' the -ed sho+ld not e4ceed the ,otent)*l "oot ,enet"*t)on de,th# ' 4 e Phragmites used in man Euro5ean s stems offer several advanta"es for a lo% m*)nten*nce treatment s stem: They w)ll g"ow *nd s,"e*d '*ste" th*n -+l"+sh> the)" "oots sho+ld go dee,e" th*n c*tt*)ls> *nd they *"e not * 'ood so+"ce 'o" m+sk"*ts *nd n+t")* wh)ch h*(e -een * ,"o-lem 'o" c*tt*)l *nd -+l"+sh wetl*nds# 7owe(e"% the h*-)t*t (*l+es 'o" * Phragmites system *"e ,"o-*-ly less th*n 'o" othe" ,l*nt s,ec)es# A n+m-e" o' systems )n the G+l' !t*tes +t)l)5e *n *nn+*l h*"(est% "eg*"dless o' .n cont"*st% "o+t)ne *nn+*l h*"(est)ng )s not ,"*ct)ced )n the ,l*nt s,ec)es +sed# E+"o,e o" *t most othe" systems )n the 3#!# .t m*y -e +se'+l to "emo(e +ndes)"*-le weeds d+")ng the e*"ly ,*"t o' the g"ow)ng se*son 'o" the ')"st 'ew ye*"s o' o,e"*t)on# :lood)ng o' the -ed s+"'*ce *'te" the )n)t)*l ,l*nt)ng c*n hel, "ed+ce weed )n'est*t)on# A "o+t)ne *nn+*l h*"(est o' the ent)"e system ,"o()des m)n)m*l -ene')ts *nd )s not "ecommended# .t )s *lso s+ggested th*t the +se o' so't t)ss+e 'lowe")ng ,l*nts -e *(o)ded *nd the"e-y el)m)n*te the need 'o" the)" *nn+*l h*"(est *nd "el*ted m*)nten*nce# W*te" le(el m*n*gement )n the !: -ed )s not only hel,'+l 'o" weed cont"ol% -+t c*n *lso -e +sed to )nd+ce dee,e" "oot ,enet"*t)on# 1*sed on e4,e")ence )n E+"o,e% )t )s cl*)med th*t )' the w*te" le(el )n the -ed )s g"*d+*lly lowe"ed )n the '*ll o' e*ch ye*" the "oots w)ll ,enet"*te to g"e*te" de,ths# A th"ee ye*" ,e")od )s cons)de"ed necess*"y 'o" Phragmites "oots to "e*ch the)" 0#E m ,otent)*l de,th# Altho+gh th)s *,,"o*ch h*s not -een t")ed )n the 3#!# )t sho+ld -e s+ccess'+l% -+t )t m*y h*(e to -e

42/0

Ch*,te" 4 "e,e*ted e(e"y ye*" 'o" the o,e"*t)on*l l)'e o' the system# The *lte"n*t)(e )s * "oot 5one whe"e the m*Bo" m*ss o' "oots *"e l)m)ted to the to, S 0#2< m )n the ,o"t)ons o' the -ed whe"e n+t")ent concent"*t)ons *"e h)gh# The Typha "oots ,enet"*ted to the '+ll de,th o' the sh*llow -ed ( 0#= m) *t the const"+cted wetl*nd system )n 1e*" C"eek# Th)s system w*s l)ghtly .o*ded% *nd s)nce )t se"(ed * ,+-l)c h)gh school )t "ece)(ed essent)*lly no w*stew*te" 'low *t n)ght% d+")ng the weekends% *nd d+")ng the s+mme" months# These do"m*nt ,e")ods when the n+t")ent concent"*t)ons wo+ld -e *t low le(els )n the -ed *"e -el)e(ed to -e * cont")-+t)ng '*cto" to the "*,)d ,enet"*t)on o' the "oot system# .t m)ght -e ,oss)-le to "e,l)c*te th)s e4,e")ence *t othe" loc*t)ons w)th cont)n+o+s 'low )' the system we"e d)()ded )nto two o" mo"e ,*"*llel cells *nd )' the )n)t)*l 'low we"e less th*n the +lt)m*te des)gn c*,*c)ty# .n th)s c*se% the w*stew*te" 'low co+ld -e *lte"n*ted -etween the cells d+")ng the s+mme" *nd '*ll months *nd "es+lt )n enh*nced "oot ,enet"*t)on )n the tem,o"*")ly do"m*nt cell# At the !*ntee ,)lot system% the ,l*nt "oots ,enet"*ted to the de,ths shown )n T*-le E w)tho+t *ny s,ec)*l m*n),+l*t)on o' w*te" le(els o" othe" s)m)l*" m*n*gement *ct)()t)es# The s)42d*y 7$T com-)ned w)th the w*"m cl)m*te *nd cont)n+o+s g"ow)ng se*son *t th)s s)te ,"o-*-ly *)l cont")-+ted to low n+t")ent cond)t)ons )n the l*tte" ,*"t o' the -ed% the"e-y )nd+c)ng "oot g"owth *nd ,enet"*t)on# As "oot de(elo,ment commences% n)t")')c*t)on sho+ld -e enh*nced> th)s sho+ld -e "*,)dly 'ollowed -y den)t")')c*t)on (*s long *s * c*"-on so+"ce )s *(*)l*-le)# The "es+lt)ng loss o' n)t"ogen to the *tmos,he"e '+"the" "ed+ces the *(*)l*-)l)ty o' n+t")ents )n the -ed *nd m*y ,"omote '+"the" ,"og"ess)(e "oot de(elo,ment )n the ,o"t)ons o' the -ed whe"e the n)t")'y)ng o"g*n)sms c*n s+ccess'+lly com,ete 'o" the *(*)l*-le o4ygen# .t )s l)kely th*t "oot de(elo,ment wo+ld st)ll -e l)m)ted )n the '"ont ,*"t o' s+ch * -ed whe"e the o4ygen dem*nd 'o" 1OD < "emo(*l wo+ld l)m)t the de(elo,ment o' the n)t")')e"s# .n th)s *"e* m+ch o' the n)t"ogen wo+ld st)ll -e )n the *mmon)* 'o"m *nd the ,l*nt "oots wo+ld not h*(e to ,enet"*te dee,ly to o-t*)n s+'')c)ent n+t")ents# A c")t)c*l d)''e"ence -etween the !*ntee ,"oBect *nd m*ny o' the o,e"*t)ng systems )n the G+l' !t*tes )s the s)42d*y 7$T *t the 'o"me" (e"s+s the one2 to two2 d*y 7$T *t2the l*tte" systems# The +se o' new ,l*nt s,ec)es% h*"(est)ng *nd othe" (eget*t)on m*n*gement *ct)()t)es *"e +nl)kely to )m,"o(e *mmon)* "emo(*l ,e"'o"m*nce *t these sho"t detent)on t)me systems# Dee, ,enet"*t)on o' the "oots )n these sho"t detent)on t)me -eds m*y -e ,oss)-le )' most o' the 'low )s *ct+*lly occ+"")ng on to, o' the -ed# .n th)s c*se the"e wo+ld -e m)n)m*l 'low th"o+gh most o' the -ed ,"o')le% "es+lt)ng )n low n+t")ent le(els

4 2 20

Ch*,te" 4

*nd dee,e" "oot ,enet"*t)on# The dee,e" "oot ,enet"*t)on )n th)s c*se wo+ld not "es+lt )n )m,"o(ed t"e*tment s)nce the "oots *"e not )n cont*ct w)th the -+lk o' the w*stew*te"# 7yd"*+l)c )m,"o(ements *"e necess*"y 'o" s+ch systems to m*)nt*)n 'low th"o+gho+t the '+ll -ed ,"o')le% -+t the sho"t detent)on t)me w)ll st)ll -e * l)m)t)ng '*cto"#

4 2 2/

Ch*,te" <

&2AP'ER 6 &O-S'RU&')O- .E'A)/S .t )s ,"+dent 'o" *ll -+t the sm*llest systems to d)()de the s+"'*ce *"e* "e;+)"ed 'o" t"e*tment )nto two o" mo"e cells% )n ,*"*llel% to ,"o()de 'le4)-)l)ty 'o" o,e"*t)on *nd E*ch cell sho+ld -e ,"o()ded w)th *n *ccess "*m, 'o" m*)nten*nce m*)nten*nce# e;+),ment# The hyd"*+l)c ,e"'o"m*nce o'2 these const"+cted wetl*nds c*n -e s)gn)')c*ntly )n'l+enced -y )m,"o,e" const"+ct)on *ct)()t)es# .n)t)*l e4c*(*t)on *nd g"*d)ng m+st -e c*"e'+lly cont"olled to *(o)d low s,ots *nd ,"e'e"ent)*l 'low down one s)de o' the cell% &*st e4,e")ence h*s shown th*t e(en w)th o" e""*t)c c"oss 'low w)th)n the cell# c*"e'+l )n)t)*l g"*d)ng% the cell ,"o')le c*n -e d)s"+,ted -y +ncont"olled t"+ck t"*'')c -")ng)ng the g"*(el o" "ock med)* )nto the -ed# .t )s s+ggested th*t the n*t)(e so)ls *t the -ottom o' the !: wetl*nd cell -e com,*cted to the s*me deg"ee "e;+)"ed 'o" * h)ghw*y s+-g"*de to w)thst*nd d*m*ge '"om t"+cks *nd othe" e;+),ment% *nd then const"+ct)on (eh)cle *ccess to the cell sho+ld -e l)m)ted d+")ng wet cond)t)ons# The l)ne"% o" othe" )m,e"me*-le -*"")e" ()' needed) goes on to, o' the com,*cted so)l% *nd the -ed med)* )s ,l*ced on to, o' the l)ne"# .' * mem-"*ne l)ne" )s +sed% * l*ye" o' s*nd2)s s+ggested to ,"e(ent ,+nct+"e o' the l)ne"# !elect)on o' med)* ty,e *nd s)5e )s c")t)c*l to the s+ccess'+l ,e"'o"m*nce o' the system# 3nw*shed c"+shed stone h*s -een +sed on * l*"ge n+m-e" o' ,"oBects# T"+ck del)(e"y o' s+ch m*te")*l d+")ng const"+ct)on c*n le*d to ,"o-lems d+e to seg"eg*t)on o' the ')nes )n the t"+ck d+")ng t"*ns)t% *nd then the de,os)t)on o' *ll o' those ')nes )n * s)ngle s,ot when the lo*d )s d+m,ed# Th)s c*n "es+lt )n n+me"o+s sm*ll -lock*ges )n the 'low ,*th *nd )nte"n*l sho"t c)"c+)t)ng w)th)n the system# W*shed stone o" g"*(el )s ,"e'e""ed# Co*"se *gg"eg*tes 'o" conc"ete const"+ct)on *"e commonly *(*)l*-le th"o+gho+t the 3#!# *nd wo+ld -e s+)t*-le 'o" const"+ct)on o' !: wetl*nd systems# A,,"o,")*te )nlet *nd o+tlet de()ces h*(e -een d)sc+ssed )n * ,"e()o+s sect)on# .t )s essent)*l th*t -oth de()ces ,"o()de 'o" +n)'o"m d)st")-+t)on *ndHo" collect)on# !ome method 'o" cont"oll)ng the w*te" le(el )n the -ed sho+ld -e +t)l)5ed 'ollow)ng the e''l+ent m*n)'old# The (eget*t)on on most o' the e4)st)ng !: wetl*nd systems h*s -een ,l*nted -y h*nd% w)th the )n)t)*l s,*c)ng "*ng)ng '"om 0#= to /#2 m (/ 2 4 't)# The +se o' )nd)()d+*l "ootH"h)5ome m*te")*l w)th * g"ow)ng shoot *t le*st 0#2 m (6 )n) )n length

<2/

Ch*,te" < )s s+ggested# The +se o' loc*lly *(*)l*-le ,l*nts )s "ecommended s)nce they h*(e *l"e*dy *d*,ted to the en()"onment*l cond)t)ons> howe(e"% these ,l*nts *"e *lso *(*)l*-le '"om comme"c)*l s+,,l)e"s# The "ootH"h)5ome m*te")*l sho+ld -e ,l*ced )n the g"*(el o" "ock med)*% *t * de,th e;+*l to the e4,ected o,e"*t)on*l w*te" le(el# The g"ow)ng shoot sho+ld ,"oBect *-o(e the s+"'*ce o' the med)*# .' m*t+"e% loc*lly *(*)l*-le ,l*nts *"e +sed% they c*n -e se,*"*ted )nto )nd)()d+*l "ootH"h)5omeHshoot +n)ts> )n these c*ses the m*t+"e stem sho+ld -e c+t -*ck to N 0#= m# (N / 't) -e'o"e ,l*nt)ng# The w*te" le(el )n the -ed sho+ld -e m*)nt*)ned sl)ghtly *-o(e the med)* s+"'*ce d+")ng ,l*nt)ng *nd 'o" se(e"*l weeks the"e*'te" to s+,,"ess weed de(elo,ment *nd ,"omote g"owth o' the ,l*nted s,ec)es# An )n)t)*l% mode"*te *,,l)c*t)on o' comme"c)*l 'e"t)l)5e"s w)ll *lso enh*nce ,l*nt de(elo,ment# W*stew*te" *,,l)c*t)ons c*n ,"o-*-ly commence s)4 to e)ght weeks *'te" ,l*nt)ng )' ()go"o+s g"owth )s o-se"(ed# An e*"ly s,")ng ,l*nt)ng )s ,"e'e""ed whene(e" ,oss)-le# The ,l*nts% *nd the"e'o"e system ,e"'o"m*nce 'o" n)t"ogen% m*y not -eg)n to "e*ch m*t+")ty *nd e;+)l)-")+m +nt)l l*te )n the second g"ow)ng se*son##

CO!T! A "ecent s+"(ey (/=) )nd)c*tes th*t the c*,)t*l costs 'o" !: wetl*nd systems *(e"*ged *"o+nd T200%000 ,e" hect*"e (T6F%000H*c) *nd the :W! systems we"e The m*Bo" cost d)''e"ence o' the two *-o+t T<0%000 ,e" hect*"e (T22%000H*c)# systems )s )n the e4,ense o' ,"oc+")ng the "ock o" g"*(el med)*% h*+l)ng )t to the s)te% *nd ,l*c)ng )t# Altho+gh the const"+ct)on cost ,e" hect*"e )s h)ghe" 'o" !: wetl*nds% the des)gn 'low "*tes *t c+""ently o,e"*t)ng !: systems *"e *lso m+ch h)ghe" th*n *t the :W! ty,e# As * "es+lt% 'o" the systems )ncl+ded )n the s+"(ey% the +n)t cost )s = = T/E=Hm (T0#E2Hg*l) o' w*stew*te" t"e*ted 'o" the !: ty,e% *nd T20EHm (T0#F6Hg*l) 'o" the :W! ty,e# 7owe(e"% m*ny o' these e*"ly !: systems we"e m+ch sm*lle" th*n mo"e "ecently des)gned !: systems% so the c+""ent +n)t costs *"e l)kely to -e h)ghe"# As shown )n T*-le =% the 1OD< "*te const*nt 'o" !: wetl*nds )s *-o+t do+-le the (*l+e 'o" :W! wetl*nds# 7owe(e"% th*t does not me*n th*t :W! wetl*nds *"e do+-le the s)5e o' !: wetl*nds 'o" the s*me cond)t)ons *nd ,e"'o"m*nce e4,ect*t)ons# The two systems m*y o,e"*te *t d)''e"ent w*te" de,ths% *nd the )nc"e*sed J,o"os)tyK (s,*ce *(*)l*-le 'o" w*te" 'low) )n the :W! c*se com,ens*tes to some2deg"ee 'o" the .n the ty,)c*l c*se% the :W! wetl*nd m)ght -e *-o+t F0 "ed+ced "*te const*nt# ,e"cent l*"ge" th*n * !: wetl*nd to *ch)e(e the s*me 1OD < ,e"'o"m*nce# :)g+"e /4 ,"esents the cost d)st")-+t)on 'o" !: wetl*nds *s de")(ed -y Conley% et *l# (/<)#

<22

Ch*,te" <

LAND CO!T CLEA$lNG $OCK

EDlA CON!T$3CT

.!C#

AAO$ CO!T CO &ONENT!

:)g+"e /4# Cost D)st")-+t)on 'o" !: Const"+cted Wetl*nds#

The l*nd costs *"e ;+)te low )n th)s c*se -+t ,"oc+"ement *nd ,l*cement o' the "ock med)* "e,"esents *-o+t <= ,e"cent o' the tot*l const"+ct)on costs# Th)s )s *n e4,ense not "e;+)"ed -y the :W! wetl*nd *lte"n*t)(e# Th)s cost d)st")-+t)on does not )ncl+de the cost 'o" *ny collect)on o" ,+m,)ng systems )n the comm+n)ty o" *ny ,"el)m)n*"y t"e*tment# :)g+"e /< ,"esents the *ct+*l const"+ct)on costs 'o" * sm*ll (0#4 h*) !: system )n so+the"n Lo+)s)*n* (=<)# The *ct+*l costs *"e "e'e"enced to the le't *4)s *nd the ,e"cent o' tot*l costs to the *4)s on the ")ght# The cost o' the "ock med)* )s com,*"*-le to th*t shown on :)g+"e /4# $ock )s not loc*lly *(*)l*-le *t th)s s)te so the m*te")*l w*s -*"ged '"om A"k*ns*s to Lo+)s)*n* *nd then t"+cked to the s)te# A lowe" cost m)ght -e e4,ected )' "ock o" g"*(el med)* we"e *(*)l*-le loc*lly# The l*nd costs )n th)s c*se we"e h)gh s)nce the system )s loc*ted )n *nd se"(es * l*"ge# "es)dent)*l s+-d)()s)on# The most cost2e''ect)(e cho)ce -etween !: *nd :W! const"+cted wetl*nds w)ll then de,end on the loc*l costs 'o" l*nd *nd 'o" the !: med)*# .' the l*nd costs *"e *s low *s shown )n :)g+"e /4% the :W! conce,t m*y -e '*(o"ed% *ss+m)ng the *dd)t)on*l l*nd needed w*s *(*)l*-le> )' the l*nd )s *s e4,ens)(e *s shown on :)g+"e /E the !: conce5t ma -e mo"e econom)c*l% *ss+m)ng * so+"ce o' low2cost med)* )s loc*lly *(*)l*-le#

<2=

Ch*,te" <

O of total

:)g+"e /<# Act+*l Cost D)st")-+t)on 'o" *n !: !ystem )n Lo+)s)*n*#

.' s)gn)')c*nt *mmon)* n)t")')c*t)on o" n)t"ogen "emo(*l )s "e;+)"ed% then the :W! conce,t w)th *n 7$T o' 6 to /0 d m*y st)ll -e mo"e econom)c*l s)nce *-o+t E2d 7$T )s "e;+)"ed 'o" *n !: system de,end)ng only on ,l*nt *(*)l*-le o4ygen# .' * "ec)"c+l*t)ng ')lte" )s +sed )n com-)n*t)on w)th the !: conce,t% the tot*l 7$T m)ght -e )n the "*nge o' 2 d ('o" w*"m cl)m*tes) *nd )t m)ght then -e the mo"e cost2e''ect)(e *lte"n*t)(e# '4e selectFon of t4e more cost-effective alternative %ill de5end on treatment "oals7 t4e availa#ilit and cost of land in t4e area7 and on t4e cost of t4e media for t4e S$ alternative: Ot4er factors include mos;uito and 5ositive odor control offered # t4e S$ conce5t7 and less concern over 5u#lic access: '4ese factors %ould favor t4e use of t4e S$ conce5t in close 5ro8imit to 5u#lic facilities and d%ellin"s:

Ch*,te" E

&2AP'ER = O--S)'E S$ WE'/A-. S,S'E+S '4e S$ %etland conce5t is 5articularl %ell suited for on-site a55lications #ecause of t4e advanta"es <odor and vector control7 5u#lic access issues@ of t4e 5rocess: Altho+gh the"e )s no gene"*l consens+s on des)gn% * l*"ge n+m-e" o' on2s)te !: wetl*nd systems h*(e -een const"+cted *nd ,l*ced )n o,e"*t)on )n Lo+)s)*n*% A"k*ns*s% Kent+cky% )ss)ss),,)% Tennessee% Colo"*do% *nd New e4)co# These systems se"(e s)ngle2'*m)ly dwell)ngs% ,+-l)c '*c)l)t)es *nd ,*"ks% *,*"tments% 2*nd comme"c)*l de(elo,ments# .n gene"*l these systems c*n ,"o()de -ette" th*n second*"y le(els o' t"e*tment *nd )n some st*tes * s+"'*ce d)sch*"ge h*s -een ,e"m)tted (d)s)n'ect)on m*y -e "e;+)"ed de,end)ng on loc*l cond)t)ons)# A st*nd*"d m+lt)2com,*"tment se,t)c t*nk )s the ty,)c*l ,"el)m)n*"y t"e*tment de()ce# G+)del)nes 'o" des)gn o' these sm*ll !: wetl*nd systems c*n -e o-t*)ned '"om st*te *genc)es )n Lo+)s)*n*% A"k*ns*s% Kent+cky *nd the T@A (/F%=E)# *ny on2s)te systems h*(e *lso -een des)gned +s)ng the s*me ')"st o"de" ,l+g 'low model desc")-ed ,"e()o+sly# !ystems o' th)s ty,e )n the so+thweste"n 3#!# *"e ty,)c*lly des)gned 'o" *n e''l+ent w)th N /0 mgHL 1OD <% N /0 mgHL T!!% *nd /0 mgHL tot*l n)t"ogen% w)th *n 7$T )n the wetl*nd -ed o' O E d (42)# A revie% of t4e various desi"n met4ods in current use su""ests t4at t4e '*A method and t4e 5lu" flo% model offer t4e most rational a55roac4 to desi"nN these two *nd the *,,"o*ch +sed )n Lo+)s)*n* w)ll -e d)sc+ssed )n det*)l#

/OU)S)A-A +E'2O. The method +sed )n Lo+)s)*n* (=E) )s de")(ed '"om the2wo"k o' Wol(e"ton% et *l# (=)% *nd *s *,,l)ed to l*"ge" sc*le m+n)c),*l systems )n the "eg)on# The system ty,)c*lly )n(ol(es * s)ngle n*""ow t"ench% e4c*(*ted )n cl*y% o" l)ned )n mo"e ,e"me*-le# so)ls# The 7$T )n the -ed )s one to two d*ys (*ss+m)ng the tot*l s,ec)')ed -ed (ol+me )s *ct)(ely cont")-+t)ng to t"e*tment)# The ,e"'o"m*nce )n e4)st)ng systemsG h*s -een somewh*t (*")*-le% -+t e''l+ent e4,ect*t)ons *"e ty,)c*lly )n the "*nge o' 1 O D< N =0 mgHL% T!! N =0 mgHL% *nd no l)m)ts on n)t"ogen# The t"enches )n the Lo+)s)*n* systems ty,)c*lly cont*)n * 0#E m (2 't) de,th o' c"+shed stone% w)th * l*ye" o' sm*lle" g"*(el on to,# The t"ench -ottoms *"e ty,)c*lly 'l*t *nd the o+tlet does not *llow *dB+stment o' w*te" le(el )n the -ed# Ammon)*

=-!

Ch*,te" E

"emo(*l )s not *n )ss+e w)th these on2s)te systems *nd )s not "e;+)"ed# O"n*ment*l 'lowe")ng ,l*nts *"e o'ten +sed *s the (eget*t)on o' cho)ce )n these systems# The -ed o+tlet m*)nt*)ns the w*te" le(el *t m)d2de,th o' the -ed to ,"o()de * w*te" so+"ce 'o" the o"n*ment*l ,l*nts# Th)s const"*)nt ,"o-*-ly "ed+ces the J*ct)(eK (ol+me )n the -ed wh)ch )s ,otent)*lly cont")-+t)ng to t"e*tment# A -ette" *,,"o*ch m)ght -e to +se *n *dB+st*-le o+tlet *nd mo"e d"o+ght "es)st*nt ,l*nts s+ch *s Phragmites. The se,t)c t*nk e''l+ent )s *,,l)ed to these -eds -y * ,e"'o"*ted ,),e loc*ted *t *-o+t the m)d2,o)nt o' de,th% *nd e4tend)ng *-o+t /H= o' the length o' the t"ench# .t )s l)kely th*t the *ct+*l 7$T )n these systems% *t des)gn 'low% )s less th*n the *nt)c),*ted one to two d*ys -ec*+se o' the hyd"*+l)c const"*)nts )m,osed -y the )nlet *nd o+tlet de()ces# The s,ec)')c g+)del)nes 'o" these systems )n Lo+)s)*n* *"e (=E)9 /# !ystems /#< m=Hd (400 g,d) o" less9

Th"ee2com,*"tment se,t)c t*nk% /2#0 m= (<00 g*l) )n ')"st com,*"tment% 0#0 m= (2<0 g*l) e*ch )n second *nd th)"d com,*"tment# Wetl*nd t"ench d)mens)ons9 0#4E m (/#< 't) dee,% 0#E/ m (2 't) w)de *nd =2 m (/0< 't) long% o" 0#0 m (= 't) w)de *nd 2/ m (F0 't) long# The to, /<0 mm (E )n) )s m*)nt*)ned )n * d"y st*te> the"e'o"e the "e;+)"ed t"e*tment (ol+me )s <#0 m= (2/0 't=) 'o" des)gn 'low N /#< m=Hd# The "ock )n the t"e*tment 5one sho+ld -e cle*n% w*shed "ock "*ng)ng '"om 2< to FE mm ( / to = )n) )n s)5e# The to, l*ye" c*n -e the s*me m*te")*l o" sm*lle" )n s)5e# The t"ench sho+ld -e l)ned w)th * ,l*st)c ')lm *t le*st /2 m)l )n th)ckness o" othe" e;+)(*lent m*te")*l# The e''l+ent ,),e 'o" the -ed w)ll -e * ,e"'o"*ted ,),e l*)d *s * he*de" *c"oss the '+ll w)dth o' the -ed% so th*t the h)gh w*te" le(el )n the -ed )s m*)nt*)ned *t * de,th o' =0< mm (/ 't) *t *ll t)mes# The )n'l+ent ,),e to the wetl*nd -ed w)ll -e * ,e"'o"*ted ,),e% e4tend)ng = m (/0 't) )nto the -ed on the cente"l)ne% w)th the )n(e"t o' the ,),e *t the l);+)d le(el )n the -ed *s de')ned *-o(e# A;+*t)c ,l*nts *,,"o(ed 'o" +se )ncl+de9

E22

Ch*,te" E

A""ow A"+m (Peltandra virginica) C*tt*)ls (Typha latifolia &)cke"elweed (Pontederia cordata) C*ll* L)ly (Zantedeschia aethiopica) Ele,h*nt E*" (Calocafia esculenta)

A""owhe*d (Sagittaria latifolia) $eed (Phragmites) C*nn* L)ly (Canna flaccida) 1+l"+sh (Scirpus americanus) G)nge" L)ly ( edychium coronatum)

Ty,)c*l ,l*nt dens)ty )s *-o+t E0 ,l*nts ,e" -ed% e(enly s,*ced% w)th * m*4)m+m o' 0#4E m (/#< 't) -etween )nd)()d+*l ,l*nts# !o)l sho+ld -e w*shed '"om "oots -e'o"e ,l*nt)ng *nd "oots m+st -e ,l*ced -elow the des)gn l);+)d le(el De*d (eget*t)on m+st -e "eg+l*"ly "emo(ed '"om the -ed *nd )n the -ed# *dd)t)on*l ,l*nts )nst*lled *s necess*"y# AdB*cent s+"'*ce "+no'' m+st -e e4cl+ded '"om the -ed -y *,,"o,")*te g"*d)ng *"o+nd the s)te# The -ed sho+ld -e /< m (<0 't) '"om *ny well o" ,ot*-le w*te" l)ne% *nd *t le*st = m (/0 't) '"om *ny ,"o,e"ty l)ne#

2# !ystems l*"ge" th*n /#< m=Hd (400 g,d)9 The th"ee com,*"tment se,t)c t*nk w)ll h*(e * tot*l (ol+me e;+*l to 2#< t)mes the des)gn d*)lyG 'low# The wetl*nd -ed m+st -e )nc"e*sed )n (ol+me -y /#4 m= ( <0 't=) 'o" e(e"y 0#4 m=Hd (/00 g,d) o' 'low *-o(e /#< m=# Othe" "e;+)"ements *"e the s*me *s *-o(e#

T@A

ET7OD

The T@A conce,t (/F) +ses * des)gn *,,"o*ch wh)ch cons)de"s the '*cto"s cont"oll)ng the hyd"*+l)c ,e"'o"m*nce o' the -ed% *nd the o"g*n)c lo*d)ng (kg 2 1 0 D<Hm Hd) on the ent"y 5one c"oss sect)on*l *"e* to *(o)d ,otent)*l clogg)ng# The tot*l *"e* "e;+)"ed 'o" t"e*tment )s then d)()ded )nto two e;+*l cells )n se")es# The t"*ns'e" st"+ct+"e% -etween the cells% )s e;+),,ed w)th *n *dB+st*-le 'low de()ce to cont"ol the w*te" le(el )n the ')"st cell# 1oth s+"'*ce m*n)'olds w)th *dB+st*-le o+tlets *nd -+")ed m*n)'olds h*(e -een +sed 'o" the )nlet st"+ct+"es# The second cell )n the T@A systems )s the s*me s)5e *s the ')"st cell *nd )s +nl)ned to ,e"m)t see,*ge o' the t"e*ted w*stew*te" )nto the g"o+nd# The ,"esent ,"oced+"e 'o" des)gn o' these cells does not t*ke )nto *cco+nt the ,e"me*-)l)ty o' the so)l -ene*th the +nl)ned cell% -+t )n the gene"*l c*se th)s second cell ,"o()des *n

E2=

Ch*,te" E )n')lt"*t)on *"e* com,*"*-le to th*t "e;+)"ed 'o" con(ent)on*l le*ch)ng -eds o" t"enches# The s,ec)')c T@A g+)del)nes *"e (/F)9

Dete"m)ne des)gn 'low (I) '"om the home% * ty,)c*l "*te )s 0#4< m=Hd (/20 g,d) ,e" -ed"oom> st*te o" loc*l "e;+)"ements w)ll go(e"n# Dete"m)ne the d*)ly o"g*n)c lo*d)ng (OL)# A (*l+e o' 0#04< kg 1OD<H,e"sonHd (0#/ l-Hd) )n the e''l+ent le*()ng the se,t)c t*nk )s *cce,t*-le#

Dete"m)ne the tot*l s+"'*ce *"e* (As) o' the -ed +s)ng the ,"e()o+sly dete"m)ned 2 = des)gn 'low *nd * s+"'*ce lo*d)ng o' =/#0 m o' -ed *"e* ,e" m Hd o' 'low (/#= 2 't Hg,d) 'o" * -ed de,th o' 0#= m (/ 't)# A -ed 0#4E m (/#< 't) dee, sho+ld -e 2 = 2 des)gned 'o" * lo*d)ng o' 2/#= m Hm Hd (0#6F 't Hg,d)# The sh*llowe" de,th )s ,"e'e""ed )' s)te cond)t)ons ,e"m)t#

The c"oss2sect)on*l *"e* (A%) )s dete"m)ned -y com,*")ng the )m,*ct o' D*"cyGs L*w% *nd o"g*n)c lo*d)ng c")te")*% *nd *do,t)ng the l*"ge" o' the two c"oss sect)on*l *"e*s# O"g*n)c lo*d)ng '*cto"9 Lo M 4#00F m Hkg 1OD <Hd (20 't Hl- 1OD <Hd) C"oss2sect)on*l *"e*9 D*"cyGs L*w9 Whe"e9 AC I k
s 2 2

A C M (Lo)(OL) A M M M M M M M
C

I H ks !
2 2

c"oss2sect)on*l *"e* o'= -ed% m ('t )# = des)gn 'low% m Hd ('t Hd)# hyd"*+l)c cond+ct)()ty = 2 = 2 2 < 0 m H d H m (6<0 't H d H ' t ) hyd"*+l)c g"*d)ent# 0#00< 'o" 'l*t -ottom# 0#0/ to 0#02 'o" / to 2 ,e"cent -ottom slo,e#

The -ed w)dth (W) c*n -e dete"m)ned s)nce the de,th h*s -een selected# *nd the c"oss2sect)on*l *"e* dete"m)ned *-o(e#

E24

Ch*,te" E The tot*l -ed length (L) c*n -e dete"m)ned -y d)()d)ng the ,"e()o+sly c*lc+l*ted s+"'*ce *"e* -y the -ed w)dth# A two2cell system wo+ld h*(e * length o' LH2 'o" e*ch cell#

An )m,e"me*-le l)ne" or low ,e"me*-)l)ty cl*y -ottom )s necess*"y 'o" the ')"st !ynthet)c l)ne"s +s)ng 202=0 m)l ,olyethylene o" cell )n * two2cell system# ,oly()nyl chlo")de *"e *cce,t*-le# W*shed ")(e" g"*(el )s the ,"e'e""ed -ed med)*% +s)ng ,e* g"*(el s)5es +, to /#= cm (0#< )nch) )n d)*mete"# The )nlet *nd o+tlet 5ones o' e*ch cell sho+ld +se < to /0 cm ( 2 to 4 )nch) stone 'o" * 0#E m (2 't) length *"o+nd *nd o(e" the )n'l+ent *nd e''l+ent m*n)'olds# !ched+le 40 &@C ,),e% w)th * /0 cm ('o+"2)nch) d)*mete" )s *cce,t*-le 'o" )nlet *nd o+tlet m*n)'olds% w)th 2#< cm (one2)nch) d")lled holes# The o+tlet m*n)'old sho+ld connect to e)the" * sw)(el)ng st*nd,),e o" * 'le4)-le hose )n * m*nhole to ,e"m)t w*te" le(el cont"ol )n the -ed# !+"'*ce w*te" m+st -e d)(e"ted *w*y '"om the -ed# The to, o' the -ed sho+ld -e m+lched# Loc*l ,l*nt s,ec)es sho+ld -e +sed on the -ed# The ,"e'e""ed s,ec)es )ncl+de9 c*tt*)l% sedge% "+sh% so't stem -+l"+sh% *nd "eeds# Deco"*t)(e% 'lowe")ng ,l*nts c*n -e +sed *"o+nd the edges o' the -ed#

An e(*l+*t)on o' th)s T@A des)gn method "e(e*ls se(e"*l conce"ns## .t does not t*ke )nto *cco+nt the tem,e"*t+"e )n'l+ence on ,e"'o"m*nce when *,,l)ed )n cold cl)m*tes# .t *ss+mes th*t )n')lt"*t)on *nd ,e"col*t)on )nto the g"o+nd w)ll -e *cce,t*-le -+t )t does not )ncl+de *ny ')eld me*s+"ements o' the *ct+*l hyd"*+l)c c*,*c)ty o' the )n2s)t+ so)ls# .t does not ,"o()de * method 'o" est)m*t)ng n)t"ogen "emo(*l )n the system 'o" loc*t)ons whe"e *mmon)* o" n)t"ogen cont"ol )s "e;+)"ed# The 7$T )n these systems w)ll ,"o-*-ly "*nge '"om = to 4 d*ys *t des)gn 'low% wh)ch m*y not -e s+'')c)ent to de*l w)th the *mmon)* le(els le*()ng most se,t)c t*nks# )n s+mm*"y% the '*A a55roac4 is 5ro#a#l conservative and acce5ta#le %4ere in-"round dis5osal is t4e final disc4ar"e 5at4%a and %4ere nitro"en limits do not a55l to suc4 a disc4ar"e: .n these c*ses% some ')eld me*s+"ements to dete"m)ne the *ct+*l hyd"*+l)c c*,*c)ty o' the so)l )s *lso "ecommended# The T@A *,,"o*ch m*y not -e

E2<

Ch*,te" E s+'')c)ently conse"(*t)(e 'o" des)gn o' systems w)th * s+"'*ce d)sch*"ge )n loc*t)ons w)th cold w)nte" cl)m*tes *nd sho+ld -e +sed w)th c*+t)on )n these c*ses#

P/U1 $/OW +O.E/ $OR O--S)'E S,S'E+S The ,l+gG 'low model h*s -een ,"esented *nd d)sc+ssed )n det*)l )n ,"e()o+s sect)ons o' th)s "e,o"t# A s+mm*"y l)st)ng o' s)m,l)')ed c")te")* *nd ,"oced+"es )s g)(en -elow to demonst"*te the *,,l)c*t)on to sm*ll sc*le on2s)te systems9
the des)gn 'low> 0#2= m Hd (E0 g,d) )s * "e*son*-le *ss+m,t)on 'o" ,e" Dete"m)ne c*,)t* 'low 'o" "es)dent)*l systems# !t*te o" loc*l c")te")* w)ll go(e"n# =

3se * m+lt)2com,*"tment se,t)c t*nk# 3se one t*nk 'o" s)ngle2'*m)ly dwell)ngs> +se two o" mo"e t*nks )n se")es 'o" l*"ge" sc*le (O /0%000 g,d) ,"oBects# The tot*l (ol+me o' the t*nk(s) sho+ld -e *t le*st tw)ce the des)gn d*)ly 'low#

Ass+me th*t the 1OD < (C%) le*()ng the se,t)c t*nk(s) )s conse"(*t)(e O /00 mgHL#

Ass+me th*t the wetl*nd e''l+ent 1OD< (C%) w)ll not e4ceed /0 mgHL#

3se cle*n% w*shed g"*(el *s the t"e*tment med)* )n the -ed% s)5e "*nge /#2< 2 2#< cm (0#< 2 / )nch)% w)th * tot*l de,th o' 0#E m (2 't)# :o" des)gn *ss+me the Je''ect)(eK w*te" de,th )n the -ed )s 0#<< m (/#6 't)# $e*son*-le est)m*tes *"e9 = 2 = 2 hyd"*+l)c cond+ct)()ty (k%) M /<00 m H m Hd (<000 't H't Hd> ,o"os)ty M 0#=6# .' * l*"ge n+m-e" o' systems *"e to -e )nst*lled +s)ng the s*me m*te")*ls% ')eld o" l*-o"*to"y test)ng 'o" hyd"*+l)c cond+ct)()ty (k%) *nd ,o"os)ty (n) )s "ecommended#

$eeds (Phragmites) *"e the ,"e'e""ed ,l*nt s,ec)es# Est)m*te the s+mme" *nd w)nte" w*te" tem,e"*t+"es to -e e4,ected )n the -ed#
o

.n the s+mme" *nd )n ye*"2"o+nd w*"m cl)m*teso 2O C )s "e*son*-le# .n cold w)nte" cl)m*tes% * w)nte" w*te" tem,e"*t+"e o' M E C )s * "e*son*-le *ss+m,t)on#

Dete"m)ne the -ed s+"'*ce *"e* w)th9

E2E

Ch*,te" E

(E)

As * s*'ety '*cto"% +se * "*te const*nt K20 wh)ch )s F< ,e"cent o' the -*se (*l+e 2/ 2/ (/#/04 d )# !o% 'o" des)gn o' sm*ll on2s)te systems K 20 M 0#626 d #
2O C% *nd w)th the othe" '*cto"s de')ned *-o(e% th)s e;+*t)on "ed+ces to9 At o

et")c9 3#! +n)t At E C 9 et")c9 3#! +n)ts

/=#=/(I) M m

(I )n m Hd) (I )n 't Hd)

A s M 4#0F(I) M 't 2

A s M = 0 # / ( I ) M m (I )n m H d ) As M 0#2(I) M 't
2

(I )n 't Hd)

AdDustments for ot4er tem5eratures7 ot4er media t 5es7 etc:7 s4ould use t4e #asic desi"n equations. Ado,t *n *s,ect "*t)o (L9W) o' 29/% c*lc+l*te -ed length (L) *nd w)dth (W) s)nce the s+"'*ce *"e* w*s dete"m)ned *-o(e# .n the gene"*l c*se% *n *s,ect "*t)o o' 29/% o" less% w)th * -ed de,th o' 0#E m (2 't) w)ll s*t)s'y the D*"cyGs L*w const"*)nts on hyd"*+l)c des)gn o' the -ed% so hyd"*+l)c c*lc+l*t)ons *"e not "e;+)"ed# )f site conditions %ill not 5ermit use of an /AW of 2A! for t4e #ed7 and a 0:= m #ed de5t47 t4en 4 draulic calculations as descri#ed 5reviousl %ill #e necessar :
o

Th)s *,,"o*ch w)ll g)(e *n 7$T o' *-o+t 2#6 d (*t 2O C) )n the -ed% wh)ch )s mo"e th*n *de;+*te 'o" 1OD< "emo(*l to N /0 mgHL# .' n)t"ogen "emo(*l to /0 mgHL )s "e;+)"ed% the s)5e o' the system sho+ld -e do+-led to ,"od+ce *n 7$T o' *-o+t s)4 d*ys# N)t"ogen "emo(*l d+")ng the w)nte" months% )n cold cl)m*tes m*y "e;+)"e *n 7$T o' *-o+t /0 d*ys# .n these c*ses% he*t loss c*lc+l*t)ons sho+ld -e ,e"'o"med to *ss+"e th*t the -ed )s *de;+*tely ,"otected *g*)nst '"ee5)ng#

E2F

Ch*,te" E Const"+ct the -ed *s * s)ngle cell 'o" s)ngle2'*m)ly dwell)ngs# 3se m+lt),le cells (*t le*st two) )n ,*"*llel 'o" l*"ge" systems# 3se cl*y o" * synthet)c l)ne" to ,"e(ent see,*ge '"om the -ed# Const"+ct the -ed w)th * 'l*t -ottom *nd * ,e"'o"*ted e''l+ent m*n)'old -ottom o' the -ed# A ,e"'o"*ted )nlet m*n)'old * 'ew )nches *-o(e the o' the -ed )s *de;+*te 'o" most sm*ll systems# These )nlet *nd o+tlet sho+ld +se 2#< to < cm (one2 to two2)nch) w*shed "ock 'o" * length o' / m (= 't)% *nd 'o" the '+ll de,th o' the -ed# The e''l+ent m*n)'old sho+ld connect to e)the" * sw)(el)ng st*nd,),e o" * 'le4)-le hose 'o" d)sch*"ge% to *llow cont"ol o' the w*te" le(el )n the -ed# The )nlet *nd e''l+ent m*n)'olds sho+ld h*(e *ccess)-le cle*no+ts *t the s+"'*ce o' the -ed# *t the -ottom 5ones *-o+t

The system *s desc")-ed *-o(e sho+ld ,"od+ce *n e''l+ent w)th 1OD < N /0 mgHL% T!! N /0 mgHL% *nd TN N /0 mgHL% *nd sho+ld the"e'o"e -e s+)t*-le 'o" e)the" s+"'*ce o" )n2g"o+nd d)sch*"ge# &e"col*t)on tests% -*s)n )n')lt"*t)on tests% o" othe" ')eld o" l*-o"*to"y techn);+es sho+ld -e +sed to dete"m)ne the hyd"*+l)c c*,*c)ty o' the n*t)(e so)ls 'o" )n2g"o+nd d)sch*"ge systems# The ,os)t)on o' the g"o+ndw*te" t*-le )n the ,"o,osed d)s,os*l *"e* m+st *lso -e dete"m)ned# The l*"ge" the system% the mo"e so,h)st)c*ted th)s test)ng sho+ld -e# 1ec*+se o' the (e"y cle*n n*t+"e o' the wetl*nd e''l+ent% )t sho+ld -e ,oss)-le to des)gn the ')n*l d)s,os*l -ed o" t"enches *t *-o+t one th)"d to one h*l' the s)5e th*t wo+ld -e "e;+)"ed 'o" d)"ect se,t)c t*nk d)s,os*l :o" e4*m,le% * ty,)c*l con(ent)on*l on2s)te system 'o" * '*m)ly o' 'o+" (/ m Hd% = 2 2 =00 g,d) m)ght )ncl+de * 4 m (/000 g*l) se,t)c t*nk *nd * 4E m (<00 't ) )n')lt"*t)on *"e* )n * s*ndy lo*m so)l# Add)t)on o' * wetl*nd com,onent w)th * E d 2 2 7$T wo+ld "e;+)"e *-o+t 26 m (=00 't ) o' *"e*# .' *,,"o,")*te c"ed)t 'o" the h)ghe" le(el o' t"e*tment )s *llowed% the tot*l *"e* 'o" the wetl*nd cell *nd the )n')lt"*t)on -ed 2 2 co+ld -e less th*n 4E m ( N <00 't )# An e(*l+*t)on o' th)s des)gn *,,"o*ch s+ggests th*t )t )s -oth mo"e conse"(*t)(e *nd mo"e 'le4)-le th*n the othe" two# .t *llows *dB+stment )n the des)gn 'o" d)''e"ent tem,e"*t+"e cond)t)ons% -ed con')g+"*t)ons% *nd e)the" s+"'*ce o" s+-s+"'*ce d)sch*"ge o,t)ons# .t )s *,,"o,")*te 'o" s)ngle2'*m)ly dwell)ngs *nd l*"ge" systems se"()ng ,+-l)c -+)ld)ngs *nd comme"c)*l est*-l)shments# As a result7 t4is a55roac4 is recommended 'o" des)gn o' on2s)te systems#
=

E26

Ch*,te" F

&2AP'ER > O'2ER PO'E-')A/ APP/)&A')O-S $OR S$ &O-S'RU&'E. WE'/A-.S Const"+cted wetl*nds *"e )n +se o" h*(e -een ,"o,osed 'o" the t"e*tment o' l*nd')ll le*ch*te% *g")c+lt+"*l "+no''% 'eed lot "+no''% *c)d m)ne d"*)n*ge% d"*)n*ge '"om co*l *nd *sh ,)les% sto"mw*te" "+no''% *nd com-)ned sewe" o(e"'lows (C!O)# .n most o' the o,e"*t)on*l systems% the wetl*nd conce,t )n +se )s most o'ten the '"ee w*te" s+"'*ce ty,e (:W!)# Th)s sect)on w)ll -")e'ly e4*m)ne the ,otent)*l 'o" the +se o' s+-s+"'*ce 'low wetl*nds (!:) 'o" these *,,l)c*t)ons# The !: conce,t )n(ol(es s+-me"ged 'low )n * -ed o' g"*(el o" c"+shed stone% *nd the des)gn )ntent )s to m*)nt*)n th*t cond)t)on *t *ll t)mes to "e*l)5e the t"e*tment .m,l)c)t )n th*t *,,"o*ch *"e the ,otent)*l *nd to *(o)d s+"')c)*l sho"t c)"c+)t)ng# *ss+m,t)ons th*t the 'low w)ll -e "el*t)(ely ste*dy st*te% *nd th*t the w*stew*te" does not cont*)n l*"ge ;+*nt)t)es o' )no"g*n)c sol)ds wh)ch m)ght le*d to "*,)d clogg)ng o' the ,o"e s,*ces )n the -ed#

S'OR+WA'ER S,S'E+S The !: system c*n *ccommod*te the d)+"n*l 'low ,*tte"n 'o" domest)c% m+n)c),*l% *nd )nd+st")*l w*stew*te" 'low -+t *"e not well s+)ted hyd"*+l)c*lly 'o" t"e*tment o' sto"mw*te" o" C!O d)sch*"ges whe"e the ,e*k 'low m*y -e se(e"*l o"de"s o' m*gn)t+de h)ghe" th*n the J*(e"*geK 'low# .t wo+ld -e +neconom)c*l to ,"o()de * g"*(el -ed l*"ge eno+gh to cont*)n% )n * s+-s+"'*ce mode% the ,e*k sto"m e(ent# The +se o' sed)ment t"*,s *he*d o' the wetl*nd co+ld "ed+ce the )m,*ct o' )no"g*n)c sol)ds% *nd the const"+ct)on o' s+'')c)ent '"ee-o*"d to cont*)n the sto"m 'low *-o(e the !: -ed w)th s+-se;+ent ste*dy2st*te d)sch*"ge th"o+gh the -ed m*y so+nd ,oss)-le# 7owe(e"% )t )s +nl)kely th*t the '+ll -ed (ol+me wo+ld -e )n(ol(ed )n t"e*tment o' the ,onded w*te"> ,"e'e"ent)*l d)sch*"ge )n * 5one ne*" the o+tlet )s * mo"e l)kely 'low ,*th# .n th)s c*se the -+lk o' the med)* m*y not cont")-+te to t"e*tment d+")ng the m*Bo" sto"m e(ents# As a result7 t4ere seems to #e ne"li"i#le *d(*nt*ges for t4e use of "ravel media7 so a $WS constructed %etland is 5ro#a#l t4e 5referred c4oice for storm%ater and &SO disc4ar"es: A :W! wetl*nd m*y tend to se"(e *s * -*tch ty,e ,l+g 'low "e*cto" )n "es,onse to sto"m e(ents# The m*Bo" t"e*tment "es,onses (othe" th*n sed)ment*t)on) w)ll ,"o-*-ly occ+" )n the st*nd)ng w*te" -etween the sto"m e(ents# Th*t t"e*ted w*te" w)ll then -e d)s,l*ced -y the )ncom)ng 'low '"om the ne4t sto"m e(ent#

F2l

Ch*,te" F /A-.$)// /EA&2A'ES !: const"+cted wetl*nds *"e -e)ng +sed 'o" t"e*tment o' l*nd')ll le*ch*tes# .n these c*ses the 'low )s "el*t)(ely +n)'o"m and low )n )no"g*n)c s+s,ended sol)ds *nd the !: wetl*nd c*n -e +sed to *d(*nt*ge# Collect)on o' *dd)t)on*l d*t* )s necess*"y 'o" * -ette" +nde"st*nd)ng o' the c*,*-)l)t)es o' the wetl*nd 'o" "emo(*l o' the com,le4 o"g*n)c *nd )no"g*n)c m*te")*ls wh)ch m*y -e 'o+nd )n le*ch*tes#

P+)-E .RA)-A1E !: wetl*nds c*n *lso -e +sed 'o" t"e*tment o' m)ne d"*)n*ge% whe"e *g*)n the 'low )s "el*t)(ely +n)'o"m *nd the t"e*tment does not "es+lt )n the ,"ec),)t*t)on *nd de,os)t)on o' l*"ge ;+*nt)t)es o' )no"g*n)c sol)ds )n the -ed# :W! wetl*nds *"e mo"e commonly +sed )n the e*ste"n st*tes to t"e*t d"*)n*ge '"om co*l m)nes% *s well *s co*l *nd *sh ,)les .n these c*ses% the ,"ec),)t*t)on *nd sto"*ge o' )"on *nd m*ng*nese )n the wetl*nd cell )s the m*Bo" t"e*tment go*l#

A1R)&U/'URA/ RU-O$$ Ag")c+lt+"*l "+no'' )s *lso s+-Bect to )nte"m)ttent ,e*k e(ents *nd h)gh )no"g*n)c sed)ment lo*ds% so :W! wetl*nds wo+ld *g*)n seem -est s+)ted 'o" these c*ses# D)sch*"ges '"om 'eed lots *nd othe" so+"ces o' h)gh o"g*n)c st"ength w*stew*te" c*n -e t"e*ted -y e)the" !: o" :W! const"+cted wetl*nds# .n -oth c*ses% ,"el)m)n*"y t"e*tment 'o" sol)ds *nd 1OD< "ed+ct)on )s necess*"y# )n summar 7 t4e use of S$ %etlands is 5ro#a#l #est suited7 #ecause of t4e 4 draulic constraints im5osed # t4e media7 for t4e treatment of %aste%aters %it4 relativel lo% solids concentrations7 under relativel uniform flo% conditions7 and in locations %4ere t4e advanta"es of t4e su#surface flo% mode <ieA no insect vectors7 4i"4er rate of treatment7 etc@ are im5ortant considerations:

F22

Ch*,te" 6

&2AP'ER 8 RESEAR&2 -EE.S $ese*"ch needs to '+"the" *d(*nce *nd +nde"st*nd the !: wetl*nd conce,t we"e d)sc+ssed *t *n E&A wo"ksho, held )n New O"le*ns% LA on !e,tem-e" 24% *nd 2<% /002# &*"t)c),*nts )n th*t wo"ksho, *"e l)sted )n A,,end)4 A# These "ese*"ch needs we"e c*tego")5ed *s Jh)ghK% Jmed)+mK *nd JlowK ,")o")ty needs% *nd *"e s+mm*")5ed -elow#

2)12 PR)OR)', RESEAR&2 -EE.S A -ette" +nde"st*nd)ng o' the n)t"ogen "emo(*l *nd n)t"ogen t"*ns'o"m*t)ons occ+"")ng )n these !: systems )s necess*"y# Th)s sho+ld le*d to the de(elo,ment o' "*t)on*l tem,e"*t+"e *nd ,oss)-ly se*son*lly de,endent des)gn models 'o" n)t"ogen "emo(*l# Add)t)on*l d*t* collect)on )s necess*"y on the s,*t)*l "es,onses to 1OD < w)th)n the !: wetl*nd -ed to ,e"m)t de(elo,ment *nd (*l)d*t)on o' )m,"o(ed des)gn models to "e,l*ce the )nte")m ,"oced+"es now )n +se# :+"the" "ese*"ch )s needed on )dent)'y)ng the o4ygen needs *nd so+"ces )n these The "ole o' the ,l*nt "oots )n ,"o()d)ng th)s o4ygen )s es,ec)*lly !: systems# )m,o"t*nt# The +se o' ,l*nt ty,es othe" th*n "eeds% "+shes% *nd c*tt*)ls needs to -e )n(est)g*ted to dete"m)ne )' o,t)m+m s,ec)es e4)sts# The need 'o" "o+t)ne ,l*nt h*"(est *lso dese"(es st+dy# ost o,e"*t)on*l !: wetl*nds demonst"*t)ng s+ccess'+l *mmon)* "emo(*l h*(e *n 7$T o' *-o+t s)4 d*ys o" mo"e# The system *t 1enton% LA h*s *,,*"ently demonst"*ted h)gh *mmon)* "emo(*ls w)th *n 7$T o' N / d# The '*cto"s "es,ons)-le 'o" th)s ,e"'o"m*nce *t 1enton need to -e de')ned# Altho+gh "ecent st+d)es )nd)c*te m)n)m*l clogg)ng )n the -eds )n(est)g*ted% the e''o"t needs to -e cont)n+ed to dete"m)ne the long2te"m ")sks o' clogg)ng#

62l

Ch*,te" 6

E''o"ts sho+ld cont)n+e to collect "el)*-le ,e"'o"m*nce d*t* '"om '+ll2sc*le o,e"*t)ng systems to con')"m *nd s+,,lement the "es+lts '"om l*-o"*to"y% g"eenho+se% *nd ,)lot2sc*le "ese*"ch#

+E.)U+ PR)OR)', RESEAR&2 -EE.S .nte"m)ttent o" -*tch ty,e 'low to *lte"n*t)ng -eds m)ght enh*nce the o4ygen st*t+s *nd the"e'o"e the *mmon)* "emo(*l c*,*-)l)ty# The *,,"o*ch sho+ld -e tested> *nd then demonst"*ted )' ,"om)s)ng# A des)gn model 'o" ,*thogen "emo(*l )n these systems wo+ld -e +se'+l% w)th the de,endency on t)me *nd tem,e"*t+"e de')ned# The "es,onse to com,le4 o"g*n)c *nd )no"g*n)c com,o+nds )n )nd+st")*l *nd *g")2chem)c*l w*stes needs de')n)t)on#

/OW PR)OR)', RESEAR&2 -EE.S The +se o' s,ec)*l)5ed med)* 'o" )m,"o(ed ,hos,ho"+s "emo(*l co+ld -e de(elo,ed *nd demonst"*ted# The "emo(*l mech*n)sms 'o" met*ls )n these systems co+ld -e -ette" de')ned# The "ole o' the ,l*nt "oots (othe" th*n se"()ng *s *n o4ygen so+"ce) )n m*)nt*)n)ng des)"*-le -ed cond)t)ons needs st+dy# The m*n*gement o' (*")*-le 'lows '"om comm+n)t)es wh)ch s+''e" '"om h)gh )n')lt"*t)onH)n'lows )n the)" sewe" systems needs cons)de"*t)on# T"e*tment o' sto"mw*te"% C!O d)sch*"ges% *n)m*l w*stes% *nd le*ch*tes needs '+"the" cons)de"*t)on#

622

Ch*,te" 0

&2AP'ER 9 &O-&/US)O-S / # The s+-s+"'*ce 'low (!:) const"+cted wetl*nd conce,t c*n o''e" h)gh ,e"'o"m*nce le(els 'o" 1OD< *nd T!! *t "el*t)(ely low costs 'o" const"+ct)on *nd o,e"*t)on *nd m*)nten*nce# .t )s ,*"t)c+l*"ly well s+)ted 'o" sm*ll to mode"*te s)5ed )nst*ll*t)ons whe"e s+)t*-le l*nd *nd med)* *"e *(*)l*-le *t * "e*son*-le# cost# 2# The odo" *nd (ecto" cont"ol o''e"ed -y the !: conce,t m*ke )t *tt"*ct)(e 'o" systems wh)ch *"e )n close ,"o4)m)ty to the ,+-l)c# These +ses "*nge '"om s)ngle '*m)ly dwell)ngs to l*"ge" de(elo,ments *nd ,+-l)c '*c)l)t)es#

=# The cost e''ect)(eness o' !: wetl*nd systems *s com,*"ed to '"ee w*te" s+"'*ce (:W!) wetl*nds 'o" the s*me w*te" ;+*l)ty go*ls w)ll de,end on the loc*l *(*)l*-)l)ty o' l*nd *nd the cost 'o" l*nd *nd 'o" the med)* +sed )n the !: conce,t# 4# Ammon)* "emo(*l )n most o' the ,"esent gene"*t)on o' o,e"*t)ng !: systems )s de')c)ent# The "e*son )s -el)e(ed to -e the l*ck o' o4ygen )n the -ed ,"o')le *nd * too -")e' 7$T to com,lete the n)t")')c*t)on "e*ct)ons# E''ect)(e *mmon)* "emo(*l h*s -een "el)*-ly est*-l)shed )n * 'ew !: wetl*nd systems# The common elements )n those systems *"e '+ll ,enet"*t)on o' the ,l*nt "oots *nd *n 7$T O = d# $emo(*l o' 1OD< *nd T!! )s not "el*ted to the *s,ect "*t)o (L9W) o' the system# !+"'*ce 'low h*s -een o-se"(ed *t * n+m-e" o' o,e"*t)on*l !: systems# Th)s )s -el)e(ed to -e l*"gely d+e to )n*de;+*te hyd"*+l)c des)gn o' the systems *nd not to clogg)ng o' the ,o"e s,*ces )n the med)*# The w*te" le(el )n the -ed c*n -e e''ect)(ely cont"olled w)th *dB+st*-le o+tlet st"+ct+"es# .t )s l)kely th*t some o4ygen )s *(*)l*-le '"om the ,l*nt "oots to s+,,o"t n)t")')c*t)on "e*ct)ons# E''ect)(e +se o' th*t o4ygen so+"ce "e;+)"es com,lete de(elo,ment o' the "oot 5one )n the -ed ,"o')le *nd s+'')c)ent detent)on t)me# Ne)the" cond)t)on )s ,"esent )n most o,e"*t)on*l !: systems# :+"the" "ese*"ch )s necess*"y to o,t)m)5e these "el*t)onsh),s#

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Ch*,te" 0 0# ethods *,,e*" to -e *(*)l*-le to )nd+ce *nd m*)nt*)n "oot ,enet"*t)on )n o"de" to enh*nce th)s o4ygen so+"ce 'o" n)t")')c*t)on# A-o+t * s)42d*y 7$T wo+ld -e necess*"y 'o" s)gn)')c*nt n)t")')c*t)on w)th * '+lly de(elo,ed "oot 5one *nd w*"m we*the" cond)t)ons# Th)s *,,"o*ch c*nnot -e +sed *s * "et"o')t 'o" most e4)st)ng systems s)nce the"e )s not eno+gh *"e* *(*)l*-le to )nc"e*se the 7$T to E d# 3se o' * "ec)"c+l*t)ng n)t")')c*t)on ')lte" )n com-)n*t)on w)th the !: wetl*nd -ed seems to 8o''e" ,"om)se 'o" s+ccess'+l *mmon)* cont"ol *nd cont)n+ed h)gh le(els o' 1OD< *nd T!! "emo(*l# Th)s com-)n*t)on m*y -e mo"e cost2e''ect)(e th*n *n :W! wetl*nd des)gned 'o" the s*me ,e"'o"m*nce le(el# The "emo(*l o' 1OD< )n !: wetl*nds shows * l)ne*" "el*t)onsh), to the 1OD< m*ss lo*d)ng +, to le(els o' *t le*st /40 kgHh*Hd (/2< .-H*cHd)# A ')"st o"de" ,l+g 'low k)net)c model ,"o()des * "e*son*-ly *cc+"*te est)m*te o' 1OD < "emo(*l ,e"'o"m*nce% *nd )s "ecommended 'o" +se *s *n )nte")m *,,"o*ch +nt)l mo"e so,h)st)c*ted models c*n -e de(elo,ed *nd (*l)d*ted# D*"cyGs L*w ,"o()des * "e*son*-le *,,"o4)m*t)on o' the hyd"*+l)c ,e"'o"m*nce )n these !: systems *s long *s the l)m)t*t)ons *"e "ecogn)5ed *nd *ccommod*ted# The hyd"*+l)c cond+ct)()ty (ks) *nd ,o"os)ty (n) o' the med)* to -e +sed )n these systems sho+ld -e tested )n the ')eld o" l*-o"*to"y ,")o" to ')n*l des)gn# To ,"o()de *n *de;+*te s*'ety '*cto"% no mo"e th*n one2th)"d Je''ect)(eK hyd"*+l)c cond+ct)()ty% *nd no mo"e th*n /0 ,e"cent ,otent)*l hyd"*+l)c g"*d)ent sho+ld -e +sed 'o" the hyd"*+l)c systems# These const"*)nts w)ll tend to l)m)t the *s,ect "*t)o 0#E m dee,# o' the me*s+"ed o' the m*4)m+m des)gn o' these to N =9/ 'o" -eds

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!: systems o' *ll s)5es sho+ld )ncl+de * ')n*l *dB+st*-le o+tlet to ,e"m)t cont"ol o' the w*te" le(el )n the -ed# L*"ge" systems (I M O <%000 g,d) sho+ld cons)de" the +se o' m+lt),le wetl*nd cells )n ,*"*llel to )m,"o(e cont"ol *nd 'le4)-)l)ty )n o,e"*t)ons# The l)m)ted systems *"e most c*ses 200H/00 ml% d*t* *(*)l*-le on "emo(*l o' 'ec*l col)'o"ms )nd)c*te th*t these c*,*-le o' *-o+t * one2 o" two2log "ed+ct)on w)th s+'')c)ent 7$T# .n th*t w)ll not -e s+'')c)ent to "e*ch the commonly *,,l)ed l)m)t o' so some 'o"m o' ')n*l d)s)n'ect)on m*y -e necess*"y#

/F#

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0-2

Ch*,te" 0

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!ome 'o"m o' ,"el)m)n*"y t"e*tment% *t le*st to the ,")m*"y le(el% )s ty,)c*lly +sed 'o" !: wetl*nd systems )n -oth the 3#!# *nd E+"o,e# &")m*"y t"e*tment +s)ng se,t)c o" lmho'' t*nks )s s+)t*-le 'o" sm*ll to mode"*te s)5ed systems# *ny e4)st)ng !: systems 'ollow '*c+lt*t)(e l*goons s)nce they we"e ty,)c*lly *dded *s :*c+lt*t)(e l*goons *"e *n *cce,t*-le 'o"m o' ,"el)m)n*"y * ,ol)sh)ng ste,# t"e*tment -+t c*n *dd l*"ge concent"*t)ons o' *lg*e# .n these c*ses * (*")*-le le(el d"*w2o'' )n the% l*goon m*y hel, "ed+ce the *lg*l lo*d on the wetl*nd com,onent#

02=

Ch*,te" /0

&2AP'ER !0 RE$ERE-&ES /# !e)del% K# ( /0EE)# $e)n)g+ng (on Gew*sse"n d+"ch hohe"e &'l*n5en !eutsche "atur#issenschaft, /2#9206220F# Deg"*d*t)on *nd )nco",o"*t)on o' n+t")ents '"om "+"*l 2# K)k+th% $# (/0FF)# w*stew*te"s -y ,l*nt "h)5os,he"e +nde" l)m)n)c cond)t)ons# $tili%ation of &anure by 'and Spreading, Comm# o' the E+"o,# Comm+n)t)te% E3$ <EF2e% London% 2=<2 24=# =# Wol(e"ton% 1#C#% $#C# cDon*ld% W#$# D+''e"% (/06=)# )c"oo"g*n)sms *nd 7)ghe" &l*nts 'o" W*stew*te" T"e*tment# (. )nvironmental *uality, /2(2)9 2=E2 242# 4# Ge"s-e"g% $# #% 1#@# Elk)ns% !#$# Lyons% C#$# Goldm*n% (/06<)# $ole o' A;+*t)c &l*nts )n W*stew*te" T"e*tment -y A"t)')c)*l Wetl*nds# +ater Research, 209=E=2 ,-.. <# 1oon% A#G# (/06<)# $e,o"t o' * @)s)t -y em-e"s *nd !t*'' o' W$C to Ge"m*ny to ln(est)g*te the $oot Uone ethod 'o" T"e*tment o' W*stew*te"s# W*te" $ese*"ch Cent"e% !te(en*ge% Engl*nd#

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/022

Ch*,te" /0 Tcho-*noglo+s% G#% :#L# 1+"ton (/00/)# +aste#ater )ngineering2 Treatment, Disposal and Reuse. Th)"d ed)t)on% cG"*w 7)ll .nc#% New Do"k% ND# 7e"skow)t5% A#% !# 1l*ck% W# Lew*ndowsk)% (/06F)# 'isto#el /rtificial &arsh )n9 A;+*t)c &l*nts 'o" W*te" T"e*tment *nd $eso+"ce Treatment Pro@ect. $eco(e"y% $eddy ? 1l*ck% ed#% 24F22<4% *gnol)* &+-l)sh)ng% O"l*ndo% :L# Ge*"he*"t% $#A#% 1#A#:)nney% !# W)l-+"% A# W)ll)*ms% D# 7+ll (/06<)# The $se of +etland Treatment Processes in +ater Reuse. )n9 :+t+"e o' W*te" $e+se% @ol2% E/F2E=6% AWWA $ese*"ch :o+nd*t)on% Den(e"% CO# Kn)ght% $#L#% $#7# K*dlec% S.C. $eed (/00/)# !atabase? "orth /merican +etlands for +ater *uality Treatment. 3n,+-l)shed .nte"n*l E&A "e,o"t% ,"e,*"ed 'o" 3#!# E&A E$L% Co"(*ll)s% O$# L)ttle% A# (/00/)# O,e"*to"% Deneh*m !,")ngs% LA# &e"son*l Comm+n)c*t)on# K*dlec% $#L#% A#T# W*tson (/00/)# ydraulics and Solids /ccumulation in a 6ravel .nte"n*t)on*l !ym,os)+m on )n9 &"oceed)ngs% 7ed Treatment +etland. const"+cted Wetl*nds 'o" W*te" I+*l)ty .m,"o(ement% Lew)s &+-l)she"s% )n ,"ess# $eed% S.C. (/00/)# Constructed +etlands Characteri%ation2Carville 1 &andeville '/. 3n,+-l)shed .nte"n*l E&A $e,o"t% ,"e,*"ed 'o" 3#!# E&A $$EL% C)nc)nn*t)% O7# Constructed +etlands Characteri%ation2 6reenleaves 1 $eed% !#C# (/002)# ammond, '/. 3n,+-l)shed .nte"n*l E&A $e,o"t% ,"e,*"ed 'o" 3#!# E&A $$EL% C)nc)nn*t)% O7% ()n ,"e,*"*t)on)# Treatment of +aste #ater in the Rhi%osphere of +etland 1")4% 7# (/06F)# Plants2 The Root2Zone &ethod. W*te" !c)ence Technology% (ol /0% /0F2//<# Process !esign &anual2 'and Treatment of &unicipal 3#!# E&A% (/06/)# +aste#ater. E&A E2<H) 26/2<0/% 3#!# E&A CE$.% C)nc)nn*t)% O7# W*tson% A#T#% $eed% !#C#% $#7# K*dlec% $#L# Kn)ght% A#E# Wh)teho+se% (/060)# Performance )Bpectations and 'oading Rates for Constructed +etlands. )n9 Const"+cted Wetl*nds 'o" W*stew*te" T"e*tment9 +n)c),*l% .nd+st")*l *nd Ag")c+lt+"*l% D# 7*mme"% ed#% =/02=</% Lew)s &+-l)she"s% Chelse*% l#

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/024

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