Ha rdne ss-Ba se d Me ta ls Crite ria in NPDE S Pe rmits BY BRI - - PowerPoint PPT Presentation

Ha rdne ss-Ba se d Me ta ls Crite ria in NPDE S Pe rmits

BY BRI AN NI CK E L US E PA RE GI ON 10

Ba c kg ro und: Ho w the E PA De te rmine s the Ne e d fo r L imits (“Re a so na b le Po te ntia l”)

 A disc ha rg e ha s “Re a so na b le po te ntia l” if the pro je c te d re c e iving

wa te r c o nc e ntra tio n e xc e e ds wa te r q ua lity c rite ria .

 T

he 99th pe rc e ntile o f the e fflue nt da ta is e stima te d using sta tistic s in Cha pte r 3 o f the E PA’ s T e c hnic al Suppo rt Do c ume nt fo r Wate r Quality- b ase d T

• xic s Co ntro l (T

SD).

 Dilutio n ma y b e c o nside re d in a re a so na b le po te ntia l a na lysis b a se d o n

a n a utho rize d mixing zo ne .

 “Critic a l” stre a m flo ws fo r mixing a re g e ne ra lly spe c ifie d in Se c tio n 210.03.b o f

the I da ho WQS.

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Ba c kg ro und: Ho w the E PA Ca lc ula te s Wa te r Qua lity-b a se d E fflue nt L imits

 I

f the re is “re a so na b le po te ntia l,” the n limits a re e sta b lishe d.

 L

imits a re g e ne ra lly c a lc ula te d b a se d o n pro c e dure s in Cha pte r 5 o f the T SD.

 Mixing zo ne a utho rize d: L

imits me e t c rite ria a t the e dg e o f the mixing zo ne .

 No mixing zo ne a utho rize d: L

imits me e t c rite ria a t the po int o f disc ha rg e (“e nd-o f-pipe ”).

 L

imits b a se d o n a q ua tic life c rite ria must me e t b o th a c ute a nd c hro nic wa te r q ua lity c rite ria .

 Bo th the a ve ra g e mo nthly limit a nd ma ximum da ily limit b a se d o n the sa me

c rite rio n (e ithe r a c ute o r c hro nic ), whic he ve r re sults in mo re string e nt limits.

 Average monthly limit ≤ chronic wasteload allocation.  Maximum daily limit ≤ acute wasteload allocation.

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Me ta ls with ha rdne ss-de pe nde nt c rite ria in I da ho

 Mo st wa te r q ua lity c rite ria a re fixe d va lue s.

 E

.g ., a q ua tic life c rite ria fo r c hlo rine , c ya nide , se le nium, a nd pe stic ide s, a nd huma n he a lth c rite ria .

 Aq ua tic life c rite ria fo r se ve ra l me ta ls a re b a se d o n ha rdne ss:

 Ca dmium, c hro mium I

I I , c o ppe r, le a d, nic ke l, silve r, a nd zinc .

 Crite ria c o nc e ntra tio ns inc re a se (i.e ., b e c o me le ss re stric tive ) with

inc re a sing ha rdne ss.

 T

he ha rdne ss va lue (a nd, in turn, the c rite ria ) must b e e sta b lishe d a s pa rt o f the re a so na b le po te ntia l a na lysis a nd e fflue nt limit c a lc ula tio ns.

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I da ho WQS Pro visio ns Re g a rding Ha rdne ss (Se c tio n 210.03.c )

 Hig h-e nd “c a p” o f 400 mg / L

a s Ca CO 3 e ve n if a c tua l ha rdne ss is g re a te r.

 L

• w e nd “flo o r” o f 25 mg / L

, e xc e pt fo r c a dmium, whic h is 10 mg / L , e ve n if a c tua l ha rdne ss is le ss.

 “T

he ha rdne ss va lue s use d fo r c a lc ula ting a q ua tic life c rite ria fo r me ta ls a t de sig n disc ha rg e c o nditio ns sha ll b e re pre se nta tive o f the a mb ie nt ha rdne sse s fo r a re c e iving wa te r tha t o c c ur a t the de sig n disc ha rg e c o nditio ns g ive n in Sub se c tio n 210.03.b .”

 Sub se c tio n 210.03.b re fe rs to the lo w flo w de sig n disc ha rg e c o nditio ns

(e .g ., 1-da y, 10-ye a r lo w flo w fo r a c ute c rite ria a nd 7-da y, 10-ye a r lo w flo w fo r c hro nic c rite ria ).

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Co nside ring the I nflue nc e o f the Disc ha rg e

 Disc ha rg e s c a n b e ha rde r o r so fte r tha n the a mb ie nt wa te r.  T

his c a n b e fa c to re d into the a na lysis in two wa ys:

 Use ha rdne ss me a sure d do wnstre a m fro m the disc ha rg e .  Ca lc ula te the do wnstre a m ha rdne ss using a ma ss b a la nc e o f the

upstre a m a nd e fflue nt ha rdne ss a nd flo w.

 I

da ho ’ s Dra ft Mixing Zo ne Guida nc e (Se c tio n 4.3.3).

 “F

• r e fflue nt with g re a te r o r lo we r ha rdne ss…tha n the re c e iving wa te r

b o dy, use a n e stima te o f the fully mixe d c o nditio ns to c a lc ula te the a pplic a b le e dg e o f mixing zo ne c o nc e ntra tio n.”

 “I

f da ta a re a va ila b le , DE Q stro ng ly sug g e sts disc ha rg e rs e xa mine the re la tio n b e twe e n flo w a nd ha rdne ss.”

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E xa mple s



Use ha rdne ss me a sure d do wnstre a m fro m the disc ha rg e .



City o f Ca ld we ll (56 mg / L a s Ca CO 3, 5th pe rc e ntile ).



City o f Me rid ia n (F ive mile Cre e k, minimum ha rd ne ss whe n flo w wa s le ss tha n the se a so na l me d ia n).

 28 mg / L

a s Ca CO 3 fro m Ma y – Se pte mb e r.

 102 mg / L

a s Ca CO 3 fro m Oc to b e r – April.



Gro use Cre e k Mine (fo r silve r a nd L e a d ).



Ca lc ula te the do wnstre a m ha rdne ss using a ma ss b a la nc e o f the upstre a m a nd e fflue nt ha rdne ss a nd flo w.



Gro use Cre e k Mine (e xc e pt silve r a nd le a d ).



City o f Me rid ia n (Bo ise Rive r).



Ha rd ne ss wa s c a lc ula te d a t the e d g e o f the mixing zo ne (no t a t c o mple te mix).



5th Pe rc e ntile wa s use d fo r b o th e fflue nt a nd upstre a m ha rd ne ss.

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Wha t’ s spe c ia l a b o ut silve r a nd le a d?

Co nc a ve do wn Co nc a ve up

0.0 5.0 10.0 15.0 20.0 25.0 20 40 60 80 100 120 140 160 180 200

Copper (ug/L) Hardness (mg/L as CaCO3)

Figure 1: Chronic Copper Criterion and Mixture

Chronic Copper Criterion Copper Mixture

2 4 6 8 10 12 20 40 60 80 100 120 140 160 180 200

Silver (ug/L) Hardness (mg/L as CaCO3)

Figure 2: Silver Acute Criterion and Mixture

Acute Silver criterion Mixture of Flows

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Que stio ns

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