catch basin minimizes sewer clogging and provides some basic storm water .mdot.state.mi.us/public/design/files/englishstandardplans/files/R001D.pdf. MDOT
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www.mi.gov/deq MDEQ NPS BMP Manual CB – 1 Rev2017.8.25 Water Resources Division C atch B as i n D e f ini t ion T h i s b e st m an a g e m e n t p r ac t i ce ( B M P ) p r ese n t s t he r ec o m m en d ed m e t h o ds o f p l ann i ng, des i g n, con s tr u c t i on, and m a i n t ena n ce o f t he c a t c h bas i n, w h i ch i s a r ece p t a c l e, r es e r v o i r , bas i n, or p i t benea t h a s t o r m se w er open i n g , f or c o ll ec t i ng s u r f a ce w a t er d r a i na g e o r r un o ff . A ca t ch b a s i n m i n i m i z es s e w er c l og g i ng and p r o v i d e s s o m e bas i c s t o r m w a t er p r e t r ea t m ent by tr app i n g l a r g e r m a tt e r w i t h an i n l et g r a te , and by a ll o w i ng sed i m ent and o t h er s m a ll er m a t e r i al t o se tt l e i n a s u m p l oc a t ed b el o w t he i n v e r t e l e v a t i o n s o f a l l ou t l et p i p e s. A l each i ng s t y l e ca t ch bas i n has an open, pe r v i ous, s t on e – f ill ed su m p b o tt o m , a ll o wi ng w a t er t o i n f ilt r a t e i n t o t he g r oun d . D esc rip t ion P o ll u t ant C on tr o ll ed P r i m a r il y coa r se sed i m e n t P a r t i c l es o f 0 . 04 i nch ( 1 m illi m e t e r ) d i a m e t e r a nd l a r g e r m ed i um or coa r se sand ( depend i ng on t he so i l c l ass i f i ca t i on s y s t em be i n g u se d ) , g r a v e l , e t c. T r e a tm e n t M echan i sm s – S e t t li ng ( i n ca t ch bas i n su m p ) ; and – I n f il tr a t i on (t h r o u g h p e rv i ous bo tt om o f l each i ng bas i n t y pe ca t c h bas i n, d esc r i bed be l o w ) P o ll u t ant R e m o v al E f f i c i ency I n g en e r a l , t he m o r e fr e quen t l y ca t ch b a s i ns a r e c l eaned ou t , t he b e tt e r t he po ll u t ant r e m o v al e f f i c i enc y . S t ud i es i nd i c a t e t hat a r e g u l a r l y c l eaned out ca t ch bas i n can a ch i e v e up t o app r o x i m a t e l y 50 pe r ce n t r e m o v al o f coa r se sed i m en t , w i t h l o w er r e m o v a l s f o r o t her pa r a m e t e r s (t o t al suspended so li ds, che m i cal o xy g en de m a n d , b i och e m i cal o xy g en de m an d , nu t r i en t s , m e t a l s , e t c . ) . C o m pan i on & Al t e r n a t e P r a c t i ces D u r i ng t he p l ann i ng s t a g e , p r i or t o s y s t e m des i g n or cons t r u c t i o n , a s an a l t e r n a t i v e t o s t o r m se w e r , cons i der a Gr a ss ed W a t e r w a y , S t o r m w a t er C on v e y ance C hannel , or o t h e r s i m il ar su r f ace w a t er con v e y ance t h a t p r o v i des ade q u a t e f l ow capac i t y and s t o r a g e , po ll u t ant r e m o v a l , s a f e t y , a nd f l ood m i n i m i z a t i on. W i t h an e x i s t i ng s t o r m s e w er s y s t e m , cons i der p r e – t r ea t i n g r un o f f e n t e r i n g t he ca t c h bas i n w i t h ca t ch b a s i n t r ea t m e n t d e v i ces, or m i n i m i z i ng t he a m ount o f m a t e r i al f l u s h ed i n t o c a t ch bas i ns by S tr eet S w eep i n g .
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www.mi.gov/deq MDEQ NPS BMP Manual CB – 2 Rev2017.8.25 Advantage s & Disadvantages One design guide ( Stormwater Center , un date d) identifies th e followin g limitation s o f catc h basins: 1. E v en ca r e f u ll y des i g ned ca t ch b a s i ns cann o t r e m o v e po ll u t an t s as w e l l as o t her s t o r m w a t er tr e a t m ent p r a c t i c e s, s u ch as w et ponds, s a nd f il t e r s, or s t o r m w a t er w e t l ands. A no t her a l t e r n a t i v e i s g r e en i n f r a s tr u c t u r e as a m e ans o f m i n i m i z i ng t he g e ne r a t i on o f s t o r m w a t er r un o ff . 2. U n l ess p r ope r l y m a i n t a i n ed, c a t ch bas i ns can be c o m e a sou r ce o f po ll u t a n t s t h r o u g h r e – suspe n s i on ( de s c r i b e d i n m o r e d e t a i l i n t h e m a i n t enance se c t i on be l o w ) ; and 3. C a t ch bas i ns cannot e ff e c t i v e l y r e m o v e so l ub l e p o ll u t an t s, or f i ne p a rt i c l es ( f i ne sand, s il t , c l a y , o r co ll o i ds ) . Lo ca t ion W i t h i n s t o r m se w er s y s t e m s, c a t ch bas i ns a r e l o c a t ed a t l ow po i n t s, and o t he r w i se spaced t o p r o v i de ade q ua t e d r a i na g e o f su r f ace w a t er r un o f f . M a t e ri a ls C a t ch bas i ns and s u m ps a r e t y p i ca ll y cons tr uc t ed o f p r eca s t conc r e t e. B r i ck and conc r e t e b l o c k a r e fr e q ue n t l y seen i n o l der s y s t e m s. I n l et co v e r s a r e m ade o f ca s t i r on. D es ign R e f e r t o F i g u r e 1 f o r a s t anda r d c a t ch bas i n sch e m a t i c , and F i g u r es 2 , 3, and 4 f or t h r ee t y pes o f s t anda r d i n l et g r a t e s . R e g a r d i n g ca t ch bas i n s i z i n g , o ne s t udy ( L a g e r e t a l , 197 7 ) i de n t i f i es t he f o ll o w i ng op t i m al c a t ch bas i n and s u m p d i m ens i on s , based on an o u t l et p i pe o f d i a m e t e r : – S u m p de p t h: A t l ea s t 4D – C a t ch bas i n d i a m e t e r : 4D – C a t ch bas i n o v e r a l l de p t h: 6 . 5D – D ep t h t o t op o f o u t l et p i pe: 1 . 5D R e f e r t o F i g u r e 5 f o r a d ep i c t i on o f t hese d i m ens i ons. A no t her d e s i g n s t udy ( Pi t t et a l , 199 7 ) s u g g es t s a ca t ch bas i n s i z i ng m e t h od i n w h i ch t he e x pec t ed s t o r m w a t er r u n o f f so li ds conce n tr a t i on i s used t o e s t i m a t e t he a m ount o f so li ds t hat wil l be co ll ec t ed be t w een su m p c l ea n – o u t s, app l y i ng a f ac t o r o f s a f e t y , and s i z i ng t he ca t ch bas i n acco r d i n g l y .
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www.mi.gov/deq MDEQ NPS BMP Manual CB – 3 Rev2017.8.25 Figure 1. Standard Catch Basin with Sump Source: Adapted from MDOT, 2001a. Minimum two (2) feet Concrete footing Figure 2. Source: Adapted from MDOT, 2004a. Figure 3. Source: Adapted from MDOT, 2004b.
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www.mi.gov/deq MDEQ NPS BMP Manual CB – 5 Rev2017.8.25 Pe r f orm a n c e E nh a n c e rs A hooded i n l et can p r e v ent f l o a t ab l e m a t e r i a l s a n d t r ash fr o m e n t e r i ng t he s t o r m d r a i n s y s t e m . A n i nc li ned sc r een m ou n t ed i n fr o n t o f ca t ch bas i n i n l et ( w he t her hooded o r s t anda r d ) can he l p cap t u r e t r ash t h a t has e n t e r ed t he ca t ch bas i n fr o m g e tt i n g i n t o t he s t o r m se w er s y s t em. A l each i ng b a s i n i s s i m il ar t o a s t and a r d ca t ch b a s i n, e x cept t hat i ns t ead o f a so li d conc r e t e base, t he l each i n g b a s i n bo tt o m co n s i s t s o f l oose agg r e g a t e , t h r o u g h w h i c h s t o r m w a t er f l o w s, and i n f il tr a t es i n t o t he g r ound unde r ne a t h. R e f er t o F i g u r e 6 f or a dep i c t i on o f a l each i n g bas i n . D o not u se l each i n g bas i ns i n a r e a s w he r e p o t en ti al g r ound w a t er con t a m i na t i on i s an i ssue, such as i n w e ll head p r o t ec t i on a r e a s. Al so n o t e t hat l each i n g bas i ns a r e c ons i de r ed by t he U n i t ed S t a t e s E n v i r on m e n t al P r o t ec t i on A g e n cy ( USEPA ) t o be Cl ass V i n j ec t i on w e ll s , and t he r e f o r e m u s t b e c o m p li ant w i t h t he i r r e q u i r e m e n t s. A se w er tr ap i s an ou t l e t p i pe an g l ed up w a r d as i t l ea v es t he ca t c h bas i n. I t can p r e v ent l a r g e so li ds f r o m l ea v i ng t he c a t ch bas i n , a c t a s an od o r co n tr ol de v i ce, and s e rv e as an o il – w a t er sepa r a t o r . I t ‘ s si m il ar i n co n f i g u r a t i on a nd op e r a t i on t o a hooded ou t l e t . R e f er t o F i g u r e 7 f o r a s t anda r d se w er t r ap s c h e m a t i c . Con s t ru c t ion I ns t a l l C ons tr u c t i on B a r r i e r s a r ound t he s i t e t o p r e v ent pedes tr i an acces s . C ons i der us i ng Di v e r s i o n s or o t h e r so i l e r os i on c o n tr ol p r ac t i ces u p – s l ope o f c a t ch bas i ns t o p r e v ent po ll u t ed r un o f f f r om e n t e r i n g t he s i t e. S e e t he S t o r m S e w er I n l et P r o t e c t i on B M P f o r w a y s of p r e v en t i n g po ll u t ed r un o f f f r om en t e r i n g t he se w e r . P os t – con s tr u c t i on m a i n t enance m ay be necess a r y r e g a r d l ess o f w he t her or n o t i n l et p r o t ec t i on w as p r o v i ded. S t ab il i z e t he s i t e f o ll o wi n g t he S eed i n g , M u l c h i n g , and S odd i ng B M P s. R e m o v e any t e m p o r a r y B M P s a f t e r v e g e t a t i on h as been e s t ab li shed. M a in t e n a n ce T he p r e f e r r ed m e t hod o f m a t e r i al r e m o v al fr o m c a t ch bas i ns i s us i n g a se w er v acuu m , r e f e rr ed t o as a v ac t o r tr u c k. S o m e r e f e r ences r ec o m m end c a t ch bas i n c l ean i ng w hen t he sed i m ent h e i g ht i n t he s u m p g e t s up t o 0 . 3 m e t e r s ( one f o o t ) be l ow t he ou t l et p i pe i n v e rt . O t h e r r e f e r ences r eco m m end c l ea n – out w hen t he sed i m ent de p t h r eaches an y w he r e f r o m 30 pe r ce n t t o 50 p e r c e nt o f t o t al su m p dep t h . T o o – i n f r e q ue n t c l ean i n g can r esu l t i n s u m p s f illi ng up t o a po i nt w he r e a n y sed i m ent e n t e r i n g ca t ch b a s in s s i m p l y pas s es on t h r o u g h t he s y s t e m . S u m ps t h a t a r e t oo f u l l of m a t e r i al a r e a l so m o r e p r on e , a t l o w er f l o w s, t o r e – suspe n s i on and pass a g e o f any p r e v i ous l y se tt l ed m a t e r i al.
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www.mi.gov/deq MDEQ NPS BMP Manual CB – 6 Rev2017.8.25 O ne s t udy ( H e rr e r a E n v i r on m en t al Co nsu l t an t s , I n c ., 200 6 ) s u g g e s t s t he f o ll o w i ng c l ea n – out fr e q uenc i e s , based on t h e l and use d r a i n i ng t o a g i v en ca t ch bas i n: – I ndus t r i a l : q u a rt e r l y t o s e m i – annua ll y – C o m m e r c i a l : s e m i – an n ua l l y – R es i den t i a l : annua ll y T h i s s t udy a l so s t a t e s t h a t , based on a r e v i ew of p r e v i ous m on i t o r i n g s t ud i es, t he r e i s a po i nt o f d i m i n i sh i ng r e t u r n s. T h a t i s, abo v e a c e rt a i n c l ea n – out fr e q uenc y , no m o r e w a t er q ua li t y ben e f i t i s g a i ne d , because so li t tl e m a t e r i al has a ccu m u l a t ed s i nce t he p r e v i ous c l ea n – ou t . Figure 6. Leaching Basin Source: Adapted from MDOT, 2001a. Loose Granular Class II Material (stone) Min. two feet Concrete footing Figure 7. Sewer Trap Source: Adapted from MDOT, 2001b. Concrete footing
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www.mi.gov/deq MDEQ NPS BMP Manual CB-8 Rev2017.8.25 References He rrera Envir onmental Consult ants , Inc. 2006. Non-S tructural Stormwater BM P Assessm ent. Technical memor andum prepared for City of Portland, OR, under work ord er num ber 14531043. h ttps:// www.po rtlandoregon.gov/ bes/article/ 133999 Lager, J.A., W .G. Smith, W.G. Ly nard, R.M. Finn, and E.J. Fi nnemore . 1977. Ur ban Stor mwater M anagement and Technology: U pdate and Users Guide . USEPA. EPA-600/8-77-014. MDEQ. 2007. Catch Basin Cleaning Activiti es Guidance Document . http://www.michigan.gov/documents/deq/wrd-stormwater-catch-basin- guidance_579858_7.pdf MDOT. 2001a. Drainage S tructur es. St andard Pl an R-1-D . S heet 2 of 5. Obtai ned from mdotwas1 .mdot.state.m i.us/public/design/f iles/eng lishst andar dplans/f iles /R001D.pdf. MDOT. 2001b. Sewer Tr ap. Sta ndard Plan R-19-B. Obtai ned from mdotwas1 .mdot.state.m i.us/public/design/f iles/eng lishst andar dplans/f iles /R019B.pdf. MDOT. 2004a. Cover E . St andard Plan R-10-C. Obtai ned from mdotwas1 .mdot.state.m i.us/public/design/f iles/eng lishst andar dplans/f iles /R010C.pdf. MDOT. 2004b. Cover G. St andard Plan R-12-D. Obtai ned from mdotwas1 .mdot.state.m i.us/public/design/f iles/eng lishst andar dplans/f iles /R012D.pdf. MDOT. 2004c. Cover R . St andard Plan R-20-C . Sheet 2 of 2. Obtai ned from mdotwas1 .mdot.state.m i.us/public/design/f iles/eng lishst andar dplans/f iles /R020C.pdf. Pitt, R. , M. L ilburn, S. Nix, S. Durr ans, and S. Burian. 1997. Guidance Manual for Int egrated Wet Weather Flow Co llecti on and Tr eatment Systems for Newly Ur banized Ar eas. USEPA Office of Research and Devel opment. Cincinnati , OH. Stormwater Center. Undated. Pollution Prevention Fact Sheets: Catch Basins.
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