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MGD Metropolitan St. Louis Sewer District 2350 Market Street St. Louis, MO 63103-2555 (314) 768-6200 May 18, 2012 RE: Notice of Updated Volume Reduction Calculator Spreadsheet and User Instructions To Whom It May Concern: The purpose of this letter is to convey Metropolitan St. Louis Sewer District (MSD) changes with regard to use of the "MEP spreadsheets", which are used to assess volume reduction as a metric of post - construction best management practice (BMP) performance. The changes resulted in significant revision to these spreadsheets. Instructions on how to use the revised spreadsheets are also provided. Change Summary Effectively immediately, MSD will evaluate runoff volume reduction based on average annual precipitation. Also, for local vegetated areas located on silt or clay soil over limestone bedrock, MSD believes that approximately 42% of annual precipitation results in discharge. (The basis for this factor is provided in the attached paper, Locally Derived Water Balance Method to Evaluate Realistic Outcomes for Runoff Reduction in St. Louis, Missouri.)' Where applicable, MSD will use this value to calculate the annual runoff from vegetated areas (e.g., turf, native grasses, and urban forest). The purpose of the MEP spreadsheets is to document expected BMP performance relative to a site's pre- BMP runoff condition, and to determine if the BMP strategies utilized meet Stormwater Phase II Permit requirements. The revised MEP spreadsheets provide little information on BMP design, and no changes in BMP performance are proposed herein. Designers are referred to the BMP Toolbox website for BMP performance requirements and design aids.2 Additional information on the design parameters that are applicable to the reduction factors in the spreadsheets is available on the Chesapeake Stormwater Network website.3 Revised MEP Spreadsheet Instructions The revised MEP spreadsheets are available on the MSD website, at http://www.stlmsd.com/engineering/planreview/bmptoolbox/calctools. This tool consists of six MS Excel worksheets, which can be individually viewed by clicking on the tabs at the bottom of the spreadsheet. In all worksheets, spreadsheet input should be provided in the cells that are shaded green. Cells that are shaded gray make calculations, or are linked to other cells. The six worksheets are described below. 1. Pre -Construction Runoff. This worksheet determines whether the site is considered new or redevelopment, and calculates the pre -development annual runoff volume (VA,pre) for the site's drainage area. ' Hoskins, 2012. Watershed Science Bulletin, Volume 3, Issue 1. 2 The BMP Tool box website is located at http://www.stlmsd.com/engineering/planreview/bmptoolbox. 3 The Chesapeake Stormwater Network website is located at http://chesapeakestormwater.neticategory/publications/design-specifications/ Step 1: Enter project name, MSD P#, computed by, checked by, and dates at the top of the worksheet. Step 2: Answer, "Is complete elimination of runoff required?" This is a project specific question. In most cases, the answer to this question will be "no". "No" is the default entry. Only answer "yes" if instructed by MSD. Step 3: Answer, "Is the site located in the Missouri, Mississippi, or Meramec River floodplain?" This is a project specific question. "No" is the default entry. Answer "yes", if the site is located in the Missouri, Mississippi, Meramec River, or other floodplain alluvium. The spreadsheet tool will pick which runoff factor to use based on the answer to this question. Vegetated (pervious) areas that are located on silt or clay soil over limestone bedrock will be assigned a runoff factor of 0.42. Vegetated areas that are located over alluvium will be assigned a value of 0.05. Step 4: Enter "Total Drainage Area (A)" in acres. The total drainage area is the watershed drainage area draining to the furthest downstream outfall. This area may be the same as or different from the acreage of land disturbance or size of the parcel. Step 5: Enter "Impervious Area" in acres. The value of this entry should reflect the total acreage of impervious area that exists within the total drainage area, prior to the development project. 2. Post -Construction Runoff. This worksheet calculates the post -development annual runoff volume (VA.Post) for the site's drainage area. Step 1: Enter project name, MSD P#, computed by, checked by, and dates at the top of the worksheet. Step 2: Enter the impervious area (in acres) that will exist within the total drainage area after the proposed construction and development is complete. (For this calculation, all pavement and roof, including permeable pavement and green roof, should be treated as impervious area. The subsequent runoff reduction calculator worksheets address the runoff reduction achieved by permeable pavement and green roof.) 3. Runoff Reduction Calculators (RR-BMP1, RR-BMP2, & RR-BMP3). The runoff reduction calculation sheets estimate the annual volume of runoff that is retained on site (not discharged by overflow or underdrain flow). BMPs can operate in a "treatment train", whereby stormwater flows between BMPs before it is discharged (Figure 1). Impervious Area BMP Group 1 BMP Group 2 BMP Group 3 Figure 1. Schematic of BMPs in Series ► Discharge Using worksheets RR-BMP1, RR-BMP2, and RR-BMP3, designers can utilize up to 3 groups of BMPs discharging (in series) to a single point. (Sites may use more than 3 groups of BMPs in series, however, this will necessitate site specific modeling requirements.) Credits or BMPs within a group can be the same, or different. If multiple credits or BMP types are used within a group, then the impervious area entered should reflect the cumulative area addressed by that type of BMP. When rainwater harvesting or other BMPs not listed in these MEP spreadsheets are used, modeling will be required to estimate the annual reduction in runoff from the rainwater harvesting or other BMP system. Based on this modeling, the fraction of runoff that is retained on site can be input into the spreadsheet (2i or 11 a, as applicable). Designers will note that the worksheets that evaluated enhancing bioretention for volume reduction have been removed. BMPs may still be enhanced to achieve additional volume reduction; however, their assessment should be based on site specific continuous simulation modeling. Step 1: Enter project name, MSD P#, computed by, checked by, and dates at the top of the worksheets. Step 2: The impervious area(s) captured by the first group of BMPs should be entered into the "RR-BMP1" spreadsheet. Only impervious areas should be entered into the runoff reduction calculator spreadsheets. Step 3: The impervious area(s) captured by the second group of BMPs or credits should be entered into the "RR-BMP2" spreadsheet. The impervious area captured by the second group must include the impervious area captured by the group 1 BMPs. Step 4: The impervious area(s) captured by the third group of BMPs or credits should be entered into the "RR-BMP3" spreadsheet. The impervious area captured by the group 3 BMPs must also include the impervious area captured in groups 1 and 2. 4. Summary Step 1: Enter project name, MSD P#, computed by, checked by, and dates at the top of the worksheet. Step 2: Review summary sheet. First, review the pre- and post -development runoff volumes (VA,Pre and VA,Post) respectively), and confirm that values appear correctly. If in error, go back to the spreadsheets labeled "Pre - Construction Runoff' and "Post -Construction Runoff" and revise input (green cells). Second, review the "Runoff Reduction" volumes (RR,,) and depths (RR.). If in error, go back to the applicable spreadsheet (RR-BMP1, RR-BMP2, or RR-BMP3) and review information. Note that the runoff reduction calculators for RR-BMP2 or RR-BMP3 will not indicate reduction if the impervious area entered is less than the impervious area treated by the upstream BMP group. Annual runoff volumes are converted to runoff depth for use in curve number modification spreadsheets. The basis for this is provided by the Center for Watershed Protection in their paper The Runoff Reduction Method. 4 Runoff depth is provided for each BMP group, as well as cumulative runoff depth. Curve number modification can be used for reducing the size of downstream detention. Curve number modification may not be used to reduce the size of detention when the water quality volume is nested within the detention volume. The net increase or decrease in runoff is calculated from VA,Post — VA,Pre — RR, Many redevelopment sites with BMPs will indicate a decrease in runoff, and this decrease can be interpreted as an improvement in the site runoff condition. The amount of the decrease needed to meet the Phase II stormwater permit's maximum extent practicable (MEP) standard is site specific, and largely determined by the pre -redevelopment site conditions and BMPs utilized by the redevelopment project. MSD suggests that, early in the project, designers check with MSD staff as to whether the District will consider the proposed approach as MEP. "Total Additional Volume Reduction Needed" calculates the additional runoff volume required to mimic pre -construction runoff conditions on new development sites. To demonstrate compliance, the value in this cell should be zero. If the BMP strategies used on a new development site do not reduce runoff volume to the pre -development estimate, then the strategy will be required to be modified. Only in very limited site -specific circumstances will variance be granted. Example Project Calculations For assistance in properly using MEP spreadsheets, attached are two sets of example calculations. Site Specific Modeling MSD provides these standard equation spreadsheets as a tool for developers and engineers who decide not to use site -specific modeling. Site -specific continuous simulation modeling - in lieu of the above MEP spreadsheets approach - is allowed as long as performance criteria are met. Please direct any questions regarding this policy to my attention, at (314) 768-2709. \Sincerely, (\t- Jay S \Hoskin , PE Princiljaing eer Erigirieering/Planning — Development Review Metropolitan St. Louis Sewer District 4 Battiata, Collins, Hirschman, and Hoffmann, 2010. Journal of Contemporary Water Research and Education. Issue 146. 1 Locally Derived Water Balance Method To Evaluate Realistic Outcomes for Runoff Reduction in St. Louis, Missouri Introduction The Metropolitan St. Louis Sewer District (MSD) is the coordi- nating authority of a 61-permittee Phase II municipal separate storm sewer system (MS4) permit. MSD is carefully following the development of new national postconstruction storm - water regulations, which focus on maintaining or restoring the runoff component of the undeveloped (i.e., natural) water balance. If the Energy Independence and Security Act (EISA) Section 438 technical guidance is the "writing on the wall" for a national rule, then development projects would be required to imple- ment postconstruction controls that capture and retain on -site (i.e., no discharge) the 95th percentile daily rainfall depth (3.8 cm in St. Louis). Stormwater professionals may question whether a rule like this would be appropriate nationwide. MSD developed a water balance model to evaluate the potential runoff reduction that may be achieved in local watersheds in response to the targeted EISA rule. The predevelopment water balance in the St. Louis region has not previously been studied for this purpose. This vignette presents a "simple" approach to developing an annual esti- mate of runoff, and one that may be a useful tool for other stormwater managers whose watersheds' predevelopment hydrology has not been assessed. Methods The water balance is the balance between the input of water from precipitation and the output of water by runoff, evapotranspiration, storage, and infiltration. Numerically, the runoff component of the water balance is expressed as R = P — ET — N — S, where R is runoff, P is precipitation, ET is evapotranspiration, N is infiltration or recharge, and S is the change in storage (in soil). The one-dimensional Thornthwaite method is used to esti- mate components of the water balance on a daily time -step. MSD used a modified version of this method, as described below. Figure 1. Example of naturally vegetated Missouri prairie and sinkhole pond. Climate, Evapotranspiration, and Vegetation MSD obtained 21 years of daily weather data from the National Weather Service' for Lambert St. Louis Airport for the period January 1989 to December 2009. We calcu- lated daily potential evapotranspiration rates according to the American Society of Civil Engineers (ASCE) standard- ized reference evapotranspiration equation, thus replacing the Thornthwaite evapotranspiration rates with the ASCE rates. We then multiplied daily reference evapo- transpiration rates by the landscape coefficient for a grass prairie (0.5), a reasonable approximation of an undeveloped, natu- rally vegetated condition in Metropolitan St. Louis and much of Missouri (see Figure 1). This prairie landscape coefficient is consistent with the US Geological Survey (USGS) rain garden report, Evaluation of Turf -Grass and Prairie -Vegetated Rain Gardens in Clay and Sand Soil, Madison, Wisconsin, Water Years 2004-2008, which estimates the landscape coefficient for a prairie -planted rain garden area to range from 0.2 to 0.7. Infiltration (Recharge) The near -surface geology of much of St. Louis City and County consists of urbanized (e.g., cut, filled, and reworked) clayey silt soil over limestone bedrock. The thickness of urbanized fill over bedrock varies greatly. MSD used results for Southwest Missouri from the USGS report, Groundwater - Flow Model and Effects of Projected Groundwater Use in the Ozark Plateaus Aquifer System in the Vicinity of Greene County, Missouri-1907-2030, to estimate groundwater recharge as only limited research and modeling of ground- water has been conducted for Metropolitan St. Louis. The surficial geologic conditions (clay or silt soil over limestone bedrock) in Southwest Missouri and St. Louis are similar in many ways. ' National Oceanic and Atmospheric Administration's National Weather Service, "NHDS Access of Historical Data," http://amazon.nws.noaa.gov/hdsb/data/archived/indez.html. SPRING2012 65 " T h e U S G S g r o u n d w a t e r r e p o r t e s t i m a t e d r e c h a r g e t o b e a n a v e r a g e o f 2 . 5 % o f a n n u a l p r e c i p i t a t i o n . T h u s , o n l y a l i m i t e d a m o u n t o f p r e c i p i t a t i o n c a n r e s u l t i n d e e p i n f i l t r a t i o n . S o i l S t o r a g e T h e m a x i m u m a v a i l a b l e w a t e r s t o r a g e i s t h e p r o d u c t o f t h e s o i l ' s p o r o s i t y ( s a t u r a t i o n ) a n d t h e t h i c k n e s s o f t h e r o o t z o n e . W h e n t h e m a x i m u m a v a i l a b l e w a t e r s t o r a g e i s e x c e e d e d , r u n o f f o c c u r s ( i f t h e p r e c i p i t a t i o n i s n o t f r o z e n ) . T h e m i n i m u m a v a i l a b l e w a t e r s t o r a g e i s t h e p r o d u c t o f t h e w i l t i n g p o i n t a n d t h e t h i c k n e s s o f t h e r o o t z o n e . T h e v a l u e s M S D u s e d i n c a l c u l a t i o n s w e r e r e p r e s e n t a t i v e o f s i l t l o a m . T h e r o o t z o n e t h i c k n e s s u s e d f o r t h e p r a i r i e c o n d i t i o n w a s 1 . 5 m ; t h i s i s c o n s i s t e n t w i t h o b s e r v a t i o n s r e p o r t e d i n t h e U S G S r a i n g a r d e n r e p o r t . M o d e l L i m i t a t i o n s T h i s m o d i f i e d T h o r n t h w a i t e w a t e r m o d e l h a s a n u m b e r o f l i m i t a t i o n s . F i r s t , t h e m o d e l d o e s n o t a c c o u n t f o r r a i n f a l l i n t e n s i t y ; t h u s , w h e r e t h e i n t e n s i t y o f t h e s t o r m e x c e e d s t h e i n f i l t r a t i o n r a t e o f t h e s o i l , r u n o f f i s u n d e r e s t i m a t e d . S e c o n d , t h e m o d e l a s s u m e s t h a t r u n o f f o c c u r s o n t h e s a m e d a y a s p r e c i p i t a t i o n . T h i s a s s u m p t i o n i s s u p p o r t e d b y r e c e n t w o r k b y D e b u s k a n d c o l l e a g u e s , w h o s h o w e d t h a t , i n a n u n d e - v e l o p e d w a t e r s h e d w i t h c l a y e y s o i l s , n e a r l y a l l p r e c i p i t a t i o n ( e v e n i n t e r f l o w ) i s d i s c h a r g e d w i t h i n 1 8 h o u r s a f t e r r u n o f f b e g i n s . T h i r d , t h i s m o d e l a s s u m e s t h a t a l l s n o w m e l t r u n o f f o c c u r s o n t h e f i r s t d a y o n w h i c h t h e a i r t e m p e r a t u r e i s a b o v e f r e e z i n g . T h i s a s s u m p t i o n m a k e s l i t t l e d i f f e r e n c e f o r a n n u a l o r s e a s o n a l w a t e r b a l a n c e c o m p a r i s o n s b e c a u s e s n o w m e l t s d u r i n g a t i m e o f y e a r w h e n s o i l i s t y p i c a l l y s a t u r a t e d a n d e v a p o t r a n s p i r a t i o n r a t e s a r e l o w . F i n a l l y , b e c a u s e t h e m o d e l i s o n e - d i m e n s i o n a l , c a l c u l a t i o n s d o n o t d i f f e r e n t i a t e b e t w e e n r u n o f f a s i n t e r f l o w o r o v e r l a n d f l o w . R e s u l t s a n d D i s c u s s i o n T a b l e s 1 a n d 2 s u m m a r i z e t h e r e s u l t s . T h e t o t a l a v e r a g e a n n u a l p r e c i p i t a t i o n w a s 1 0 0 c m ; o f t h i s , 4 2 % r e s u l t e d i n r u n o f f , p r i m a r i l y b e t w e e n J a n u a r y a n d J u l y . T a b l e 1 . S u m m a r y o f w a t e r b a l a n c e c o n d i t i o n s . C o m p o n e n t A n n u a l Q u a n t i t y ( c m ) P e r c e n t a g e o f A n n u a l P r e c i p i t a t i o n E v a p o t r a n s p i r a t i o n 5 5 5 5 D e e p I n f i l t r a t i o n 2 . 5 2 . 5 R u n o f f 4 2 4 2 T a b l e 2 . S u m m a r y o f r u n o f f ( d i s c h a r g e ) c o n d i t i o n s . T i m e P e r i o d A n n u a l A v g . R u n o f f ( c m ) R u n o f f a s % o f A n n u a l P r e c i p i t a t i o n R u n o f f a s % o f Q u a r t e r l y P r e c i p i t a t i o n T o t a l 4 2 4 2 J a n u a r y - - M a r c h 1 2 1 2 6 0 A p r i l J u n e 1 6 1 6 5 0 J u l y S e p t e m b e r 5 5 1 9 O c t o b e r D e c e m b e r 9 9 4 0 F o r t h c o m i n g n a t i o n w i d e s t o r m w a t e r r e g u l a t i o n s m a y m a n d a t e t h a t r u n o f f f r o m a d e v e l o p e d s i t e s h o u l d a m o u n t t o o n l y 5 % o f a n n u a l r a i n f a l l . H o w e v e r , t h i s s t u d y s h o w s t h a t r u n o f f a c c o u n t s f o r a m u c h g r e a t e r p e r c e n t a g e o f a n n u a l r a i n f a l l ( 4 2 % ) a n d i s a n a t u r a l p r o c e s s i n u n d e v e l o p e d , n a t u - r a l l y v e g e t a t e d c o n d i t i o n s i n S t . L o u i s , M i s s o u r i . B y i l l u s t r a t i n g t h a t r u n o f f ( d i s c h a r g e ) i s a m a j o r c o m p o n e n t o f t h e w a t e r b a l a n c e i n u n d e v e l o p e d , n a t u r a l c o n d i t i o n s , t h i s a n a l y s i s s u g g e s t s a s h o r t c o m i n g t o a n a t i o n w i d e r e t e n t i o n r u l e a p p l i e d t o l o c a l w a t e r s h e d s . D u r i n g s u m m e r , r a i n f a l l i s a b s o r b e d i n t o t h e s o i l a n d t h e n r e m o v e d t h r o u g h e v a p o - r a t i o n a n d t r a n s p i r a t i o n . B e c a u s e e v a p o t r a n s p i r a t i o n r a t e s a r e h i g h e s t d u r i n g s u m m e r m o n t h s , m u c h o f t h e s o i l ' s w a t e r - h o l d i n g c a p a c i t y i s a v a i l a b l e t o a b s o r b p r e c i p i t a t i o n t h r o u g h e a r l y f a l l . H o w e v e r , a f t e r r a i n f a l l o c c u r s i n l a t e f a l l , s o i l b e c o m e s s a t u r a t e d . S n o w t h a t a c c u m u l a t e s o v e r a l r e a d y s a t u r a t e d s o i l r e s u l t s i n m i d - w i n t e r s n o w m e l t r u n o f f . R a i n f a l l i n l a t e w i n t e r a n d e a r l y s p r i n g , e v e n s m a l l e v e n t s , r e s u l t s i n r u n o f f . I n t h i s m o d e l , a b o u t 6 7 % o f t h e a n n u a l r u n o f f o c c u r r e d f r o m p r e c i p i t a t i o n e v e n t s w i t h r a i n f a l l d e p t h s l e s s t h a n t h e 9 5 t h p e r c e n t i l e d a i l y r a i n f a l l . R e q u i r i n g r e t e n t i o n o f a l l s t o r m s l e s s t h a n t h e 9 5 t h p e r c e n t i l e d a i l y r a i n f a l l i s n o t a s u r r o g a t e f o r w a t e r b a l a n c e r e s t o r a t i o n . C o n c l u s i o n s A t t e m p t s t o m i m i c t h e r u n o f f c o n d i t i o n s o f a n u n d e v e l o p e d , n a t u r a l l y v e g e t a t e d s i t e c a n b e a f f e c t e d b y m a n y f a c t o r s , e s p e c i a l l y t h e a v a i l a b l e w a t e r s t o r a g e c a p a c i t y o f t h e s i t e ' s s o i l . A v a i l a b l e w a t e r c a p a c i t y i s a f f e c t e d b y w e a t h e r , g e o l o g y , s o i l t y p e , v e g e t a t i o n , a n d e v a p o t r a n s p i r a t i o n . A c l e a r d e f i n i t i o n o f p o s t c o n s t r u c t i o n b e s t m a n a g e m e n t p r a c - t i c e p e r f o r m a n c e g o a l s i s n e e d e d . H o w e v e r , r e q u i r i n g r e t e n - t i o n o f a l l s t o r m s u p t o t h e 9 5 t h p e r c e n t i l e d a i l y r a i n f a l l i s d i f f i c u l t t o j u s t i f y i n S t . L o u i s a n d i n m u c h o f M i s s o u r i a n d i s p o t e n t i a l l y c o u n t e r p r o d u c t i v e t o t h e i m p r o v e m e n t o f w a t e r 6 6 W A T E R S H E D S C I E N C E B U L L E T I N �% 1 q u a l i t y . I n s t e a d , a b a l a n c e d p e r f o r m a n c e g o a l c o m p o s e d o f s o m e i n f i l t r a t i o n a n d s o m e a t t e n u a t e d d i s c h a r g e w o u l d b e t t e r a p p r o x i m a t e a n a t u r a l c o n d i t i o n . L i s t o f S o u r c e s A S C E - E W R I T a s k C o m m i t t e e o n S t a n d a r d i z a t i o n o f R e f e r e n c e E v a p o t r a n s p i r a t i o n . 2 0 0 5 . T h e A S C E s t a n - d a r d i z e d r e f e r e n c e e v a p o t r a n s p i r a t i o n e q u a t i o n . F i n a l r e p o r t . R e s t o n , V A : A m e r i c a n S o c i e t y o f C i v i l E n g i n e e r s , E n v i r o n m e n t a l a n d W a t e r R e s o u r c e s I n s t i t u t e . D e b u s k , K . M . , W . F . H u n t , a n d D . E . L i n e . 2 0 1 1 . B i o r e t e n t i o n o u t f l o w : D o e s i t m i m i c n o n u r b a n w a t e r s h e d s h a l l o w i n t e r f l o w ? J o u r n a l o f H y d r o l o g i c E n g i n e e r i n g 1 6 ( 3 ) : 2 7 4 - 2 7 9 . R i c h a r d s , J . M . 2 0 1 0 . G r o u n d w a t e r - f l o w m o d e l a n d e f f e c t s o f p r o j e c t e d g r o u n d w a t e r u s e i n t h e O z a r k P l a t e a u s A q u i f e r S y s t e m i n t h e v i c i n i t y o f G r e e n e C o u n t y , M i s s o u r i - 1 9 0 7 - 2 0 3 0 . S c i e n t i f i c I n v e s t i g a t i o n s R e p o r t 2 0 1 0 - 5 2 2 7 . R e s t o n , V A : U S G e o l o g i c a l S u r v e y . S e l b i g , W . R . , a n d N . B o l s t e r . 2 0 1 0 . E v a l u a t i o n o f t u r f - g r a s s a n d p r a i r i e - v e g e t a t e d r a i n g a r d e n s i n c l a y a n d s a n d s o i l , M a d i s o n , W i s c o n s i n , w a t e r y e a r s 2 0 0 4 - 2 0 0 8 . S c i e n t i f i c I n v e s t i g a t i o n s R e p o r t 2 0 1 0 - 5 0 7 7 . R e s t o n , V A : U S G e o l o g i c a l S u r v e y . T h o r n t h w a i t e , C . W . , a n d J . R . M a t h e r . 1 9 5 7 . I n s t r u c t i o n s a n d t a b l e s f o r c o m p u t i n g p o t e n t i a l e v a p o t r a n s p i r a t i o n a n d t h e w a t e r b a l a n c e . P u b l i c a t i o n s i n C l i m a t o l o g y , v o l . 1 0 , n o . 3 . C e n t e r t o n , N J : D r e x e l I n s t i t u t e o f T e c h n o l o g y . U S E n v i r o n m e n t a l P r o t e c t i o n A g e n c y . 2 0 0 9 . T e c h n i c a l g u i d a n c e o n i m p l e m e n t i n g t h e s t o r m w a t e r r u n o f f r e q u i r e - m e n t s f o r f e d e r a l p r o j e c t s u n d e r S e c t i o n 4 3 8 o f t h e E n e r g y I n d e p e n d e n c e a n d S e c u r i t y A c t . E P A 8 4 1 - B - 0 9 - 0 0 1 . W a s h i n g t o n , D C : U S E n v i r o n m e n t a l P r o t e c t i o n A g e n c y . C o n t r i b u t o r T h i s v i g n e t t e w a s p r e p a r e d b y J a y H o s k i n s , P E , M e t r o p o l i t a n S t . L o u i s S e w e r D i s t r i c t . K I N G F I S H E R S P O N S O R B a k e r b r i n g s a b a l a n c e d a p p r o a c h t o w a t e r r e s o u r c e s a n d f l o o d p l a i n m a n a g e m e n t , f a c i l i t a t i n g r e g u l a t o r y c o m p l i a n c e a n d e n v i r o n m e n t a l p r o t e c t i o n w h i l e i m p l e m e n t i n g s u s t a i n a b l e s o l u t i o n s . B a k e r i s a l e a d e r i n I n t e g r a t e d W a t e r R e s o u r c e s M a n a g e m e n t . W e u s e t h e r i g h t t o o l s a n d m e t h o d s t o a d d r e s s y o u r w a t e r c h a l l e n g e s . W a t e r s h e d P l a n n i n g & M a n a g e m e n t " W a t e r Q u a l i t y & T M D L S e r v i c e s C o a s t a l E n g i n e e r i n g " F l o o d R i s k M a p p i n g & M a n a g e m e n t " F l o o d p l a i n M a n a g e m e n t E m e r g e n c y M a n a g e m e n t " P r o g r a m & P r o j e c t M a n a g e m e n t " H & H M o d e l i n g " G I S " E c o s y s t e m R e s t o r a t i o n S t o r m w a t e r M a n a g e m e n t " S o u r c e W a t e r P r o t e c t i o n " W a t e r S u p p l y " W a s t e w a t e r M a n a g e m e n t T o l e a r n m o r e a b o u t B a k e r ' s c o m p r e h e n s i v e s e r v i c e s , v i s i t w w w . m b a k e r c o r p . c a m o r c o n t a c t F e r n a n d o P o s q u e I ( f p a s q u e l @ m b a k e r c o r p . c o m ) a t 7 0 3 . 3 1 7 . 6 2 1 9 o r D o u g P l a s e n c i a { d p L a s e n c i a @ m b a k e r r o r p . c o m } a t 6 0 2 . 7 9 8 , 7 5 5 2 . S P R I N G 2 0 1 2 6 7 I EA j Metropolitan St. Louis Sewer District WATERSHED SHEET NO OF JOB NO. TITLE: f\AE? cv1LArE"“t 01P14- Co ',nil.? e&-amieJop eriv SUBJECT TITLE BY A v),. c-- DATE 2, CHECKED X? a" DATE 6-146Z. Vr#14-- PIT.,reaNce- $2- 1D ._ET 61•31.*1 f3 I tp SLETEt4110+S ovEQ_L-m4b, -DiFtale.,0412 Pk- kLAL)e- -1.14,prtAik 04;,W-c. -1c, - Otat,c V.W.4.4‘.14 1 2 3 4 7 8 Al 8 CID I E I F IGIHI I I J I K I L I M LN C I P I Q I R I S I T I U I V I W I X I Y Project Name: MEP Commercial Example MSD P#: P#29xxx-xx Computed By: 'ABC Checked By: Is complete elimination of runoff required? (If so, answer "yes" and skip this sheet.) Date: Date: 5116/2012 062012 9 Is the site located in the Missouri, Mississippi, or Meramec River floodplain? 10 (If so, answer "yes". This answer determines the pre -development runoff factor.) 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 Pre -Construction Development Input Total Drainage Area (A) = ® Ac. Impervious Area = Ac. Vegetated Area = 0.20 Ac. P = 39.4 (Annual Average Rainfall at Site. Use P = 39.4") rio THIS IS A REDEVELOPMENT SITE. USE WATER QUALITY STRATEGIES TO MAXIMUM EXTENT PRACTICABLE. Compute % Impervious (I)= I=Impervious Ac./Total Ac.*100 1= 1.05 Ac./ 1.25 Ac. *100 I= 84 % Compute Pre -Construction Annual Runoff Volume (V, prp)= VA,Pre = P*Rv-impervious*Aimpervious/12 + P*Rv-pervious*Apervious/12 = Ac. Ft. Rv = 0.95 for impervious area Rv = 0.42 for pervious areas over limestone bedrock (e.g., most upland areas in St. Louis County and City) Rv = 0.05 for pervious areas over river alluvium (e.g., most river floodplain, including most levee protected areas) P*Rv-impervious*Aimpervious/12 = 3.28 Ac. Ft. P*Rv-pervious*Apervious/12 = 0.28 Ac. Ft. VA,Pre 3.55 Ac-ft VA,pre = 154,638 CF Pre -Construction Runoff 5/16/2012 Al BIC F J L 0 0 T 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Project Name: MEP Commercial Example Computed By: ABC, Date: MSD P#: P#29xxx-xx Checked By: Y Date: Post -Construction Dev. Input Total Drainage Area (A) = Impervious Area = Vegetated Area = P= Ac. Ac. 0.31 Ac. 39.4 (Annual Average Rainfall at Site. Use P = 39.4") 1.25 Compute Post -Construction Annual Runoff Volume (VA prP)= VA,Post = P*Rv-impervious*Aimpervious/12 + P*Rv-pervious*Apervious/12 = Ac. Ft. Rv = 0.95 for impervious area Rv = 0.42 for pervious areas over limestone bedrock (e.g., most upland areas in St. Louis County and City) Rv = 0.05 for pervious areas over river alluvium (e.g., most river floodplain, including most levee protected areas) P*Rv-impervious*Aimpervious/12 = 2.93 Ac. Ft. P*Rv-pervious*Apervious/12 = 0.43 Ac. Ft. VA,Post = 3.36 Ac-ft VA,Post = 146,362 CF 5/16/2012 5/1812012 1 of 1 Post -Construction Runoff 5/16/2012 A I B I C I 0 1 E 1 F 1 0 1 H 1 2 3 4 5 6 8 9 10 11 12 13 14 15 16 MSD Runoff Reduction Method Worksheet Adapted from Virginia Runoff Reduction Method Worksheet Courtesy of Center for Watershed Protection Project Name: MEP Commercial Example Computed By: ABC Date: 5/16/2012 MSD P#: P#29xxx-xx Checked By: XYZ Date: 5/18/2012 _ -NEM data input cells calculation cells constant values 1. Post -Development Project & Land Cover Information Constants Annual Rainfall (inches) 1 39.40 Land Cover Summary 17 Weighted Rv(forest) 0.42 18 Rv(impervious) 0.95 19 20 2. 1st Tier BMPs (BMP 1) : Apply Runoff Reduction Practices to Reduce Treatment Volume & Post -Development Load 21 2215. 23 Credit Green Roos Unit Description of Credit Credit Credit Area (acres) (cf for Credit 2.1) Adjustment to Treatment Volume (cf) 1.a. Green Roof (Extensive) acres of green roof 45% runoff volume reduction 0 45 , r "p¢_ 24 1.b. Green Roof (Intensive) acres of green roof 65% runoff volume reduction 0.65 t . . ,. 0 26 26 27 2. Rooftop 0iscenneotion 2.a. Simple Disconnection to A/B Soils impervious acres disconnected 50% runoff volume reduction 0.50 0.0l2 0 28 2.b. Simple Disconnection to C/D Soils impervious acres disconnected 25% runoff volume reduction - 025 0.00 0 29 2.c. Disconnection To Amended C/D Soils impervious acres disconnected 50% runoff volume reduction 0.50 0 30 2.d. To Dry Well or French Drain (C/D Soil, w/Underdrain) impervious acres disconnected 50% runoff volume reduction 0.50 0 31 2.e. To Dry Well or French Drain (A/B Soil, w/ Internal Water Storage Underdrain) impervious acres disconnected 90% runoff volume reduction _ 0.90 - 0 32 2.f. To Rain Garden (C/D soil, w/ Underdrain) impervious acres disconnected 50% runoff volume reduction 0_550 0 33 2.g. To Rain Garden (C/D soil, w/ Internal Water Storage Underdrain) impervious acres disconnected 55% runoff volume reduction -, 0.55 0 34 2.h. To Rain Garden (A/B soil, w/ or w/out Internal Water Storage Underdrain) impervious acres disconnected 80% runoff volume reduction 0.80 0 35 2.i. To Rainwater Harvesting (Site Specific Design) impervious acres captured based on tank size and design (Site Specific Design) p 36 2.j. To Bioretention Planter Box (Water Tight, w/Underdrain) impervious acres disconnected 40% runoff volume reduction 040 p 37 38 39 3. Permeable Pavement 3.a. Permeable Pavement (C/D Soils w/Underdrain) acres of permeable pavement + acres of "external" u ( pgradient) impervious pavement 45% runoff volume reduction (2 45 - 0.. 1 43411 40 Internal 41 3.b. Permeable Pavement (A/B soils w/ acres of permeable pavement 75% runoff volume reduction 0.75 0,00 0 Water Storage Underdrain) acres of "external" (upgradient) impervious pavement 45% runoff volume reduction _0.45 0.00 0 1 ef3 RR-BMPI 5/16/2012 A I B I C I D I E J F I G J H 1 2 3 4 5 7 8 9 10 11 12 13 14 15 16 MSD Runoff Reduction Method Worksheet Adapted from Virginia Runoff Reduction Method Worksheet Courtesy of Center for Watershed Protection RvO)sef Name: MEP Commercial Example Computed By: ABC Date: 5/16/2012 MSD:P#_... _ P#29xxx-xx Checked By: XYZ - - Date: 5/18/2012 data input cells calculation cells constant values 1. Post -Development Project & Land Cover Information Constants Annual Rainfall (inches) I 39.40 Land Cover Summary 17 Weighted Rv(forest) 0.42 18 Rv(impervious) 9.95 19 20 2. 1st Tier BMPs (BMP 1) : Apply Runoff Reduction Practices to Reduce Treatment Volume & Post -Development Load 21 Credit Unit Description of Credit Credit Credit Area (acres) (cf for Credit 2.1) Adjustment to Treatment Volume (cf) 42 43 44 4. Grass Channels 4.a. Grass Channel A/B Soils impervious acres draining to grass channels 20% runoff volume reduction ` 0.20 0 45 4.b. Grass Channel C/D Soils impervious acres draining to grass channels 10% runoff volume reduction O10 0 46 4.c. Grass Channel with Compost Amended Soils as per specs impervious acres draining to grass channels 30% runoff volume reduction ' 0.30 0 47 48 5. aty Swale 49 5.a. Dry Swale (Turf, C/D Soils w/Underdrain) impervious acres draining to dry Swale 40% runoff volume reduction 0.40 0.0O 7 50w/out 5.b. Dry Swale (Turf, A/B Soils, w/ or Internal Water Storage Underdrain) impervious acres draining to dry Swale 60% runoff volume reduction 0.50 41111.L r. 51 52 6. Blureterltioll 6.a. Bioretention (C/D soil, w/Underdrain) Impervious acres draining to ltioretenrlon 50% runoff volume reduction 0 50 MO 0 6.a. Bioretention (C/D soil, w/ Internal Water Storage Underdrain) impervious acres draining to bioretention 55% runoff volume reduction 0.55 040 0 6.b. Bioretention (A/B soil, w/ or w/out Internal Water Storage Underdrain) impervious acres draining to bioretention 80% runoff volume reduction 0.80 0,000 0 57 7. Infiltration 58 7.a. Infiltration Basin or Trench (C/D Soils, w/ Internal Water Storage Underdrain) impervious acres draining to infiltration 50% runoff volume reduction 0.50 59 7.b. Infiltration Basin or Trench (AB Soils, w/ or w/out Internal Water Storage Underdrain) impervious acres draining to infiltration 90% runoff volume reduction 0.90 0 64 9II 66 mperv9ous Surface Sheettow to Filler Strip/Open Space 9.a. Sheetflow to Conservation Area with impervious acres draining to A/B Soils conserved open space 75% runoff volume reduction for treated area 0.75 0 67 9.b. Sheetflow to Conservation Area with impervious acres draining to C/D Soils conserved open space 50% runoff volume reduction for treated area 0.50 0 RR-BMP1 5/16/2012 A I B I_ C J D [ E I F I G I H 1 2 3 4 e 7 e 9 10 11 12 13 14 15 16 MSD Runoff Reduction Method Worksheet Adapted from Virginia Runoff Reduction Method Worksheet Courtesy of Center for Watershed Protection Project Name: MEP Commercial Example Computed By: ABCMIlt Pate: 5/16/2012 MSD P#: P#29xxx-xx Checked By: XYZ•• Date: 5/18/2012 Al. data input cells calculation cells constant values 1. Post -Development Project & Land Cover Information Constants Annual Rainfall (inches) I 39.40 Land Cover Summary 17 Weinhted Rv(frarect) 0.42 16 Rv(impervious) 0.95 19 20 2. 1st Tier BM Ps (BMP 1) : Apply Runoff Reduction Practices to Reduce Treatment Volume & Post -Development Load I Credit Unit Description of Credit _ Credit Credit Area (acres) (cf for Credit 2.1) Adjustment to Treatment Volume (cf) 68 9.c. Sheet0ow to Vegetated Filter Strip in A Soils or Compost Amended 13/CAD Soils impervious acres draining to conserved open space 50% runoff volume reduction for treated area 0.50 Wirt 0 71 10. Wet Swiss 10.a. Wet Swale #1 impervious acres draining to ,met swats 10% runoff volume reduction 0 It)O.CO 0 72 10.b. Wet Swale #2 impervious acres draining to wet swale 20% runoff volume reduction 0.20 0.00 — - 0 73 7i 75 11. Site spucific BMP 1 1.a. 5ESrCRI9iw HERE impervious acres draining to BMP Based on site -specific continuous simulation modeling 0.00 Q.G'0 f 76 ) VOLUME REDUCTION BY PRACTICE. BMP 1 (cf)I 43,411 3 013 RR-BMPI 5/16/2012 I A I B 1 C ( D I E I F G ( 8 1 2 3 4 5 MSD Runoff Reduction Method Worksheet Adapted from Virginia Runoff Reduction Method Worksheet Courtesy of Center for Watershed Protection Project Name: MEP Commercial Example Computed By: ABC Gate: 5/16/2012 MSD P#__: _ _ P#29xxx-xx _ Chec.k6;.d By: XY Uatc; 5/18/2012 6 7 8 9 10 11 12 13 data input cells calculation cells constant values 1. Post -Development Project & Land Cover Information Constants 14 Annual Rainfall (inches) 1 39.40 1 15 16 Land Cover Summary 17 Weighted Rv(forest) 0.42 18 Rv(impervious) 0.95 19 20 2. 2nd Tier BMPs (BMP 2) :Apply Runoff Reduction Practices to Reduce Treatment Volume & Post -Development Load 21 II. Credit Unit Green Roof ! 0escrl"tion of Credit Credit Cra4ll Area (acres) (Treatment (cf for Credit 2.i) Adjustment to Volume (cf) 23 1.a. Green Roof (Extensive) acres of green roof 45% runoff volume reducllan 0.45 0 24 1.b. Green Roof (Intensive) acres of green roof 65%runoff volume reduction 0.65 10 25 ?fi 1.2..Rooftop Disconnection 27 2.a. Simple Disconnection to A/B Soils impervious acres disconnected 50% runoff volume reduction 0.50 0,[SQ. 26 2.b. Simple Disconnection to C/D Soils impervious acres disconnected 25% runoff volume reduction 3.25 0.00 0 29 2.c. Disconnection To Amended C/D Soils impervious acres disconnected 50% runoff volume reduction 0.50 ¢p0. 0 30 2.d. To Dry Well or French Drain (C/D Soil, w/Underdrain) impervious acres disconnected 50% runoff volume reduction 0.5G 11.1_39 31 2.e. To Dry Well or French Drain (A/B Soil, w/ Internal Water Storage Underdrain) impervious acres disconnected 90% runoff volume reduction 0.90 0.00 0 32 2.f. To Rain Garden (C/D soil, w/ Underdrain) impervious acres disconnected 50 % runoff volume reduction 0.50 (1,30 0 2.g. To Rain Garden (C/D soil, w/ Internal 33 Water Storage Underdrain) impervious acres disconnected 55% runoff volume reduction 0.55. 006 0 2.h. To Rain Garden (A/B soil, w/ or w/out 34 Internal Water Storage Underdrain) impervious acres disconnected 80 % runoff volume reduction 0.83 1100 0 2.i. To Rainwater Harvesting (Site 35 Specific Design) impervious acres captured based on tank size and design (Site Specific Design) 1 01. C.90 0 2.j. To Bioretention Planter Box (Water 36 Tight, w/Underdrain) impervious acres disconnected 40% runoff volume reduction 0.40 .0,00 0 37 38 'i3. Permeable Pavement — — 3.a. Permeable Pavement (C/D Soils w/Underdrain) 39 — acres of permeable pavement + acres of'external" (upgradient) impervious pavement 45% runoff volume reduction 0.45 0.S0 0 40 3.b. Permeable Pavement (A/B soils w/ acres of permeable pavement 75% runoff volume reduction C 7` 0.00 C Internal Water Storage Underdrain) 41 acres of "external" (upgradient) impervious pavement 45% runoff volume reduction 0.45 ..:..or 1 0 1 o13 RR-BMP2 5/16/2012 A I B I C I D I E I F 1 G I H 1 2 3 4 5 6 7 a 9 10 11 f2 13 14 15 16 MSD Runoff Reduction Method Worksheet Adapted from Virginia Runoff Reduction Method Worksheet Courtesy of Center for Watershed Protection Project Name: MEP Commercial Example Computed By: ABC Date: 5/16/2012 MSD P#: P#29xxx-xx Checked By: XYZ Date: 5/18/2012 data input cells calculation cells constant values 1. Post -Development Project & Land Cover Information Constants Annual Rainfall (inches) ) 39.40 Land Cover Summary 17 Weighted Rv(forest) 0.42 18 Rv(impervious) 0.95 19 20 2. 2nd Tier BMPs (BMP 2) :Apply Runoff Reduction Practices to Reduce Treatment Volume & Post -Development Load 21 Credit Unit Description of Credit Credit Credit Area (acres) (cf for Credit 2.1) Adjustment to Treatment Volume (cf) 42 43 44 4. Grass Charrnafs 4.a. Grass Channel A/B Soils impervious acres draining to grass channels 20 % runoff volume reduction 0.20 0 45 4.b. Grass Channel C/D Soils impervious acres draining to qrass channels 10% runoff volume reduction 0.10 0 46 4.c. Grass Channel with Compost Amended Soils as per specs impervious acres draining to grass channels 30% runoff volume reduction 0.30 0 47 48 49 5. D . Swale. 5.a. Dry Swale (Turf, C/D Soils impervious acres draining to w/Underdrain) dry awale 40% runoff volume reduction 0.40 0 5.b. Dry Swale (Turf, A/B Soils, w/ or impervious acres draining to w/out Internal Water Storage Underdrain) d 6 : le 60% runoff volume reduction 0.6t7 " 0 51 57. 53 y ..�: .' _ — 6.a. Bioretention (C/D soil, w/Underdrain) impervious acres draining to biaretention 50% runoff volume reduction — 0.50 0.u- 42154 54 55 6.a. Bioretention (C/D soil, w/ Internal Water Store.e Underdrain) impervious acres draining to Biorelention 55% runoff volume reduction .. _ _ _ 6.b. Bioretention (A/B soil, w/ or w/out Internal Water Storage Underdrain) impervious acres draining to Bioretention 80 % runoff volume reduction 0.80 9.0.. 0 56 57 58 �7.Infiltration 7.a. Infiltration Basin or Trench (CID Soils, w/ Internal Water Storage Underdrain) impervious acres draining to infiltration 50% runoff volume reduction - 0.60 G1.0➢ _ 0 59 7.b. Infiltration Basin or Trench (NO Soils, w/ or w/out Internal Water Storage Underdrain) impervious acres draining to Inlllratipn 90% runoff volume reduction p 0.90 0.00 0 64 65 66 8:Im.ervious Surface Sheetflow to FitterStripf0pen Space 9.a. Sheetflow to Conservation Area with NB Soils impervious acres draining to 75% runoff volume reduction for treated conserved open space 'area 0.75 . 0 67 9.b. Sheetflow to Conservation Area with C/D Soils impervious acres draining to 50 % runoff volume reduction for treated conserved open space area 0.50 o RR-BMP2 5/16/2012 A I B I C I D I E I F I G I H 1 2 3 4 s 6 7 8 9 10 11 12 :11 14 15 16 MSD Runoff Reduction Method Worksheet Adapted from Virginia Runoff Reduction Method Worksheet Courtesy of Center for Watershed Protection Project Name: MEFCommercial Example Computed By: ABC Date: 5/16/2012 MSD P#: PMxxx-xx Checked By: XYZ Date: 5/1II/2012 data input cells calculation cells constant values 1. Post -Development Project & Land Cover Information Constants Annual Rainfall (inches) I 39.40 ( Land Cover Summary 17 Weighted Rv(forest) 0.42 18 Rv(impervious) _ 0.95 19 26 2. 2nd Tier BMPs (BMP 2) :Apply Runoff Reduction Practices to Reduce Treatment Volume & Post -Development Load 21 Credit Unit Description of Credit Credit Credit Area (acres) (cf for Credit 2.1) Adjustment to Treatment Volume (cf) 68 9.c. Sheetflow to Vegetated Filter Strip in A Soils or Compost Amended B/C/D Soils impervious acres draining to conserved open space 50% runoff volume reduction for treated area 0.50 tS.ah 69 70 71 10. Wet Swales 10.a. Wet Swale #1 impervious acres draining to wet swale I 10% runoff volume reduction I 0.10 iz 10.b. Wet Swale #2 j impervious acres draining to wet swale 20 % runoff volume reduction 0.20 5 - 0 73 74 75 3 11- Site Specific BMP t ; DESCRIBE HERE impervious acres draining to BMP Based on site -specific continuous sunulatron rnoaeiing 0 76 77 ... ' VOLUME REDUCTION BY PRACTICE, BMP 2 (cf)I 42,154 3013 RR-BMP2 5/162012 A B 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 F G H I J K L 1 M j°;P C Project Name: MEP Commercial Example Computed By: ABC Date: MSD P#: 1.11110"likt Checked By: XYZ Date: Pre -Construction Development Input Total Drainage Area (A) = Impervious Area = Vegetated Area = 1.25 Ac. 1.05 Ac. 0.20 Ac. THIS IS A REDEVELOPMENT SITE. USE WATER QUALITY STRATEGIES TO MAXIMUM EXTENT PRACTICABLE. VA, pre = 154,638 CF Post -Construction Dev. Input Total Drainage Area (A) = Impervious Area = Vegetated Area = VA, Post = 146,362 CF 1.25 Ac. 0.94 Ac. 0.31 Ac. Runoff Reduction BMP Group Volume (RR, cf) Depth (RRd, in.) * Volume Reduction, BMP 1 43411 0.3 Volume Reduction, BMP 2 42154 0.3 Volume Reduction, BMP 3 0 0 RR=Total BMP Volume Reduction Provided= 85565 CF 0.6 in* VA,Post - VA,Pre - RR = -93,841 CF] Total Additional Volume Reduction Needed= 0 CF * For use in curve number modification spreadsheets, for sizing downstream detention basins. 5/16/12 5/18/12 Summary Sheet 5/16/2012 FA 1 Metropolitan St. Louis Sewer District WATERSHED SHEET NO. OF JOB NO. TITLE: V\ E? Spr-40,As\...2.st_V ien es 0 atzc- ArC (LIZ) ftt SUBJECTTITLE BY Or DATE Ea CHECKED — DATE rbh 2- er-'r 'DV tz-Lot.6) \sz-e 4.7-to PhAeNbait, L.• Du.ton06 TD t?,t 01/4.1c0, Cosucre., DitN-vo "rb eic4trrerr) 4 (Lb 04_ 9-5040c 71' CLC_. (1OSL ip s. cA-,triej ND Tr4cra41cr.... rApaso tboS. Net,4 2.2tert3o10.4 I r1:7, De„-tirA 1:711t4- 11‘t—reolk. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 AIBI C ID E F it L P:1 Project Name: MEP Residential Example MSD P#: P#29xxx-xx Computed By: ��4BC Date: Checked By: Date: Is complete elimination of runoff required? (If so, answer "yes" and skip this sheet.) N 5r1612012_iV ,/ 1 ,z 0 P Is the site located in the Missouri, Mississippi, or Meramec River floodplain? (If so, answer "yes". This answer determines the pre -development runoff factor.) Pre -Construction Development Input Total Drainage Area (A) = 4.35 Ac. Impervious Area = IAA& Ac. Vegetated Area = 4.35 Ac. P = 39.4 (Annual Average Rainfall at Site. Use P = 39.4") Q R _ 5 I T THIS IS A NEW DEVELOPMENT SITE. POST -CONSTRUCTION RUNOFF SHALL MIMIC PRE- EXISTING RUNOFF TO MAXIMUM EXTENT PRACTICABLE. Compute % Impervious (I)= I=Impervious Ac./Total Ac.*100 1= 0.00 Ac./ 4.35 Ac. *100 I= 0 % U V W Compute Pre -Construction Annual Runoff Volume (VA prn)= VA,Pre — P*Rv-impervious*Aimpervious/12 + P*Rv-pervious*Apervious/12 = AC. Ft. Rv = 0.95 for impervious area Rv = 0.42 for pervious areas over limestone bedrock (e.g., most upland areas in St. Louis County and City) Rv = 0.05 for pervious areas over river alluvium (e.g., most river floodplain, including most levee protected areas) P*Rv-impervious*Aimpervious/12 = 0.00 Ac. Ft. P*Rv-pervious*Apervious/12 = 6.00 Ac. Ft. VA,Pre = 6.00 Ac-ft VA,Pre = 261,360 CF x Y Pre -Construction Runoff 5/16/2012 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 A 0 0 F 0 J L 0 P 0 R s T Project Name: MEP Residential Example Computed By: ABC Date: MSD P#: P#29xxx-xx Checked By: XYZ Date: Post -Construction Dev. Input Total Drainage Area (A) = 4.35 Ac. Impervious Area = Ac. Vegetated Area = 2.15 Ac. P = 39.4 (Annual Average Rainfall at Site. Use P = 39.4") Compute Post -Construction Annual Runoff Volume (Vo prp)= VA,Post = P*Rv-impervious*Aimpervious/12 + P*Rv-pervious*Apervious/12 = Ac. Ft. Rv = 0.95 for impervious area Rv = 0.42 for pervious areas over limestone bedrock (e.g., most upland areas in St. Louis County and City) Rv = 0.05 for pervious areas over river alluvium (e.g., most river floodplain, including most levee protected areas) P*Rv-impervious*Aimpervious/12 = 6.86 Ac. Ft. P*Rv-pervious*Apervious/12 = 2.96 Ac. Ft. VA,Post 9.83 Ac-ft VA,Post = 428,195 CF 5/16/2012 5/1812012 Post -Construction Runoff 5/16/2012 A B 1 1 2 3 4 © f El- El © m 11 IIIk1 El El 16 MSD Runoff Reduction Method Worksheet Adapted from Virginia Runoff Reduction Method Worksheet Courtesy of Center for Watershed Protection Project Name: MEP Residential Example Computed By: ABC Date: 5/16/2012 MSD P#: P#29xxx-xx Checked By: XYZ Date: 5/18/2012 - -- ' data input cells calculation cells constant values 1. Post -Development Project & Land Cover Information Constants Annual Rainfall (inches) I 39.40 Land Cover Summary i7 Weighted Rv(forest) 0.42 18 Rv(impervious) 0.95 19 20 2. lst Tier BMPs (BMP 1) : Apply Runoff Reduction Practices to Reduce Treatment Volume & Post -Development Load 21 22 23 Credit Unit 1..Groan Roof Credit Area (acres) De sc rl.tion of Credit Credd ict for Credit 2.i) M Adjustment to Treatment Volume (cf) 1.a. Green Roof (Extensive) acres of green roof 45% runoff volume reduction 0.45 i- 10 0 24 1.b. Green Roof Intensive acres of .reen roof 65% runoff volume reduction 0.65 0•r'._ „ 25 26 27 2.:Rooftop RisconrIeClion 2.a. Sim • le Disconnection to A/B Soils impervious acres disconnected 50% runoff volume reduction 0.50 MS.. G 28 2.b. Sim•le Disconnection to C/D Soils impervious acres disconnected 25% runoff volume reduction _ - 0.25 p. 1 0 29 2.c. Disconnection To Amended C/D Soils impervious acres disconnected 50% runoff volume reduction 0.50 .117 11549 30 2.d. To Dry Well or French Drain (C/D Soil, w/Underdrain) impervious acres disconnected 50% runoff volume reduction 0.50 - - -• 4 3) 2.e. To Dry Well or French Drain (NB Soil, w/ Internal Water Storage Underdrain) impervious acres disconnected 90% runoff volume reduction - 0.90 _ 32 2.f. To Rain Garden C/D soil w/ Underdrain impervious acres disconnected 50% runoff volume reduction 0.50 i i- 33 2.g. To Rain Garden (C/D soil, w/ Internal Water Storage Underdrain impervious acres disconnected 55% runoff volume reduction 0.55 9 34 2.h. To Rain Garden (A/B soil, w/ or w/out Internal Water Storage Underdrain) impervious acres disconnected 80% runoff volume reduction 0 80 0.5l• 0 35 2.i. To Rainwater Harvesting (Site S.ecific Desi.n impervious acres ca•tured based on tank size and design (Site S.ecific Desi•n 1 . . �.�L 0 2.j. To Bioretention Planter Box (Water Tight, w/Underdrain) impervious acres disconnected 40% runoff volume reduction 0 IG 0 38 (3. 39 Permeabto Pavement 3.a. Permeable Pavement (C/D Soils w/Underdrain) acres of permeable pavement + acres of "external' (upgradient) impervious .avement 45% runoff volume reduction 0.4S IIII 40 Internal 41 3.b. Permeable Pavement (A/B soils w/ acres of .ermeable .avement 75% runoff volume reduction 0 75 0.00 0 Water Storage Underdrain) acres of "external" (upgradient) impervious pavement 45% runoff volume reduction 0.45 0:06 0 RR-BMP1 5/16/2012 J 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 I B I C I D I E I- F I G I H MSD Runoff Reduction Method Worksheet Adapted from Virginia Runoff Reduction Method Worksheet Courtesy of Center for Watershed Protection Project Name: MEP Residential Example Computed By: ABC Date: 5/16/2012 MSD P#: P#29xxx-xx Checked By XYZ Date: 5/18/2012 A data input cells calculation cells constant values 1. Post -Development Project & Land Cover Information Constants Annual Rainfall (Inches) Land Cover Summary Weighted Rv(forest) 39.40 0.42 18 Rv(impervious) 0.95 19 20 21 2. 1st Tier BMPs (BMP 1) : Apply Runoff Reduction Practices to Reduce Treatment Volume & Post -Development Load Credit Unit Description of Credit Credit Credtt Area (acres) (cf for Credit 2.1) Adjustment to Treatment Volume (cf) 42 93 44 •: • 4.a. Grass Channel A/B Soils impervious acres draining to •rass channels 20% runoff volume reduction 0 D.20 45 4.b. Grass Channel CID Soils impervious acres draining to •rass channels 10% runoff volume reduction 0.10 0 46 4.c. Grass Channel with Compost impervious acres draining to Amended Soils as per specs •rass channels 30% runoff volume reduction 0 30 - 0 1&DrySwaI8 49 - 0.4.0 0 y 5.a. Dry Swale (Turf, C/0 Soils w/Underdrain impervious acres draining to dr swage 40°re runoff v•lume reduction 50 5.b. Dry Swale (Turf, A/B Soils, w/ or w/out Infernal Water Storage Underdrain) impervious acres draining to d Swale fi0% runoff volume reduction 0.60 0 51 1iotlion 53 6. 6.a. Bioretention (C/D soil, w/Underdrain) impervious acres draining to broratenDon 50% runoff volume reduction 6 0.59 54 6.a. Bioretention (C/D soil, w/ Internal impervious acres draining to Water Store .e Underdrain) broretention 55% runoff volume reduction 0.55 7 55 6.b. Bioretention (A/B soil, w/ or w/out impervious acres draining to Internal Water Store geUnderdrain) bioretention 80% runoff volume reduction 0.80 0.(:r 56 17. 58 infiltration Basin or Trench (C/D Soil w/ Internal Soils,, w/Internal Water Storage impervious acres draining to Und-rdrain initltretton 50% runoff volume reduction 0.50 59 7.b. Infiltration Basin or Trench (AIB Soils, w/ or w/out Internal Water Storage impervious acres draining to Underdrain infiltration 90% runoff volume reduction 0.90 0 64 66 9.1m rvious Surface Sheetflow to Filler StriptOpen Space impervious acres draining to 75% runoff volume reduction for treated conserved Darn 5. ace area 0.75 0 9.a. Sheetflow to Conservation Area with A/B Soils 67 9.b. Sheetflow to Conservation Area with impervious acres draining to 50"/9 runoff volume reduction for treated C/D Soils conserved ❑• = n 5 •ace area 0.50 ... n RR-BMP1 5/16/2012 A 1 B I C L D 1 E 1 F 1 G I H MSD Runoff Reduction Method Worksheet 2 Adapted from Virginia Runoff Reduction Method Worksheet 3 Courtesy of Center for Watershed Protection 4 Project Name: MEP Residential Example Computed By: ABC Date: 5/16/2012 s MSD P#: P#29xxx-xx Checked By: XYZ Date: 5/18/2012 data input cells 6 8 calculation cells 9 constant values 10 11 1. Post -Development Project & Land Cover Information 12 13 Constants 14 Annual Rainfall (inches) I 39.40 15 16 Land Cover Summary 17 Weighted Rv(forest) 0.42. 18 Rv(impervious) 0.95 19 20 2. 1st Tier BMPs (BMP 1) : Apply Runoff Reduction Practices to Reduce Treatment Volume & Post -Development Load Adjustment to Credit Area (acres) Treatment 21 Credit _ Unit Description of Credit _Credit (cf for Credit 2.1) Volume (cf) 9.c. Sheet0ow to Vegetated Filter Strip in impervious acres draining 10 50/ runoff volume reduction for treated 68 A Soils or Compost Amended B/C/D Soils conserved open space area 0.50 1 0 69 10..Wet.Smiles. impervious acres draining to 0.a. Wet Swale #1 71 we: swale 10% runoff volume reduction 0.1 o fop I D.b. Wet Swale #2 impervious acres draining to 72 wet swale 20% runoff volume reduction 0420 73 74 11. Site Specific 13MP -.a DESCRIBE HERE impervious acres draining to Based on site -specific continuous 75 _ BMP , simulation modeling 0 76 VOLUME REDt1CTIQN BY PRACTICE, BMP 1 (cf)I 11,549 3 of3 RR-BMPI 5/16/2012 A I 8 I C I D 1 E 1 F I G 1 H 1 2 3 4 5 s 7 8 9 10 11 i2 13 14 15 16 MSD Runoff Reduction Method Worksheet Adapted from Virginia Runoff Reduction Method Worksheet Courtesy of Center for Watershed Protection Project Name: MEP Residential Example Computed By: ABC Date: 5/16/2012 MSD P#: P#29xxx-xx Checked By: XYZ Date: 5/18/2012 = . data input cells calculation cells constant values 1. Post -Development Project & Land Cover Information Constants Annual Rainfall (Inches) 1 39.40 Land Cover Summary 17 Weighted Rv(forest) 0.42 18 Rv(Impervious) 0.95 19 20 2. 2nd Tier BMPs (BMP 2) :Apply Runoff Reduction Practices to Reduce Treatment Volume & Post -Development Load 21 22 23 Credit Unit De en. on of Credit 1. Green Rout Adjustment to Credit Area (acres) Treatment Credit (cf for Credil 2.i) Volume (cf) 1.a. Green Roof (Extensive) acres of green roof 45% runoff volume reduction 0.45 0.00 0 24 1.b. Green Roof (Intensive) acres of green roof 65 % runoff volume reduction 0.85 0.09. 7 25 9 27 2.:Roofto trisconneetion 2.a. Simple Disconnection to A/B Soils impervious acres disconnected 50% runoff volume reduction 0.50 '• _0(..0 26 2.b. Simple Disconnection to C/D Soils impervious acres disconnected 25% runoff volume reduction 0.25 C.00 29 2.c. Disconnection To Amended C/D Soils impervious acres disconnected 50% runoff volume reduction 0.50 I, f.) 0 30 2.d. To Dry Well or French Drain (C/D Soil, w/Underdrain) impervious acres disconnected 50% runoff volume reduction 0.50 31 2.e. To Dry Well or French Drain (A/B Soil, w/ Internal Water Storage Underdrain) impervious acres disconnected 90% runoff volume reduction 0.90 lillkill: 0 32 2.f. To Rain Garden (C/D soil, w/ Underdrain) impervious acres disconnected 50% runoff volume reduction 0.50 0 33 2.g. To Rain Garden (C/D soil, w/ Internal Water Storage Underdrain) impervious acres disconnected 55% runoff volume reduction 0.55 r .fry 0 34 2.h. To Rain Garden (A/B soil, w/ or w/out Internal Water Storage Underdrain) impervious acres disconnected 80% runoff volume reduction 0.80 1:e_4___.__ _. 35 2.i. To Rainwater Harvesting (Site Specific Design) impervious acres captured based on tank size and design (Site Specific Design) 1,90 0 36 2.j. To Bioretenlion Planter Box (Water Tight. w/Underdrain) impervious acres disconnected 40% runoff volume reduction 0.40 _ 0 37 38 l3. 39 Permea61e Pavement 3.a. Permeable Pavement (C/D Soils w/Underdrain) acres of permeable pavement + acres of "external" (upgradient) impervious pavement 45% runoff volume reduction 045 0,00 . 0 40 41 3.b. Permeable Pavement (A/B soils w/ acres of permeable pavement 75% runoff volume reduction 0 75 0:00 0 Internal Water Storage Underdrain) acres of "external" (upgradient) impervious pavement 45% runoff volume reduction -- 0.45 — 0 1013 RR-9MP2 5/16/2012 A I B I C I D I E I F 1 G 1 H 1 2 3 4 ©MSD 13 Illy 10 ID m it III ® EEI 115 16 MSD Runoff Reduction Method Worksheet Adapted from Virginia Runoff Reduction Method Worksheet Courtes of Center for Watershed Protection Project Nafne: MEP Residential Example Computed By: ABC' Date: 5/1 6/201 2 P#: P#29xxx xx Che.cked Bv: XY Date: 5/18/2012 data input cells calculation cells constant values 1. Post -Development Project & Land Cover Information Constants Annual Rainfall (inches) I 39.40 Land Cover Summary 17 Weighted Rv(forest) 0.42 18 Rv(impervious) 0.95 19 zo 2. 2nd Tier BMPs (BMP 2) :Apply Runoff Reduction Practices to Reduce Treatment Volume & Post -Development Load 21 Credlt Unit Description of Credit Credit Credit Area (acres) (cf for Credit 2.1) Adjustment to Treatment Volume (cf) 42 43 44 4.GrassChannel5 - 4.a. Grass Channel A/B Soils impervious acres draining to grass channels 20% runoff volume reduction 0.20 45 4.b. Grass Channel C/D Soils impervious acres draining to grass channels 10% runoff volume reduction 0.10 46 4.c. Grass Channel with Compost Amended Soils as per specs impervious acres draining to grass channels 30% runoff volume reduction 0.30 47 46 49 5. Dry Swale 5.a. Dry Swale (Turf, C/D Soils impervious acres draining to w/Underdralnd swale 40% runoff volume reduction 0.40 50 5.b. Dry Swale (Turf, NB Soils, w/ or { w/out Internal Water Storage Underdrain) impervious acres draining to dr swale 60% runoff volume reduction 0 0.600 51 52 53 6. Bioretention — 6.a. Bioretention (C/D soil, w/Underdrain) impervious acres draining to bioretention 50%tunofivolume reduction •:r .6 — 0 54 6.a. Bioretention (C/D soil, w/ Internal Water Storage Underdrain) impervious acres draining to bioretention 55%runoff volume reducton 0.55 — 2.20 158052 55 6.b. Bioretention (A/B soil, w/ or w/out Internal Water Storage Underdrain) impervious acres draining to bioretention 80% runoff volume reduction 0. Al 56 57 7. Infiltration 58 7.a. Infiltration Basin or Trench (C/D Soils, w/ Internal Water Storage Underdrain) impervious acres draining to Infiltration — 50% runoff volume reduction D.50 0.00 0 7.b. Infiltration Basin or Trench (A/B Soils, w/ or w/cut Internal Water Storage Underdrain) impervious acres draining to intltrabon 90% runoff volume reduction 0.90 0 65 66 9.Impervious Surface Shnetflow to Filter SiriptOpen Space 9.a. Sheetflow to Conservation Area with impervious acres draining to 75% runoff volume reduction for treated A/B Soils conserved open space ar8a 0.75 0 9.b. 67 Sheetflow to Conservation Area with impervious acres draining to 50% runoff volume reduction for treated C/D Soils conserved open space area 0.50 0 RR-BMP2 5/16/2012 3 A I 6 ) 1 2 3 4 MSD Runoff Reduction Method Worksheet Adapted from Virginia Runoff Reduction Method Worksheet Courtesy of Center for Watershed Protection Project:Name: MEP Residential Example Computed By: ABC Date: 5/16/2012 MSD P#: P#29xxx-xx .Checked B.y. XYZ Date: 5/18/2012 6 7 8 9 10 1 12 13 data input cells calculation cells constant values 1. Post -Development Project & Land Cover Information Constants 14 Annual Rainfall (inches) 1 39. 40 1 15 16 Land Cover Summary 17 Weighted Rv(forest) 0.42 18 Rv(impervious) 0.95 19 lu 2 2nd Tier BMPs (BMP 2) :Apply Runoff Reduction Practices to Reduce Treatment Volume & Post -Development Load Credit Unit Description of Credit Credit Credit Area (acres) (cf for Credit 2.1) Adjustment to Treatment Volume (cf) 68 9.c. Sheetflow to Vegetated Filter Strip in A Soils or Compost Amended B/C/D Soils impervious acres draining to conserved open space 50% runoff volume reduction for treated area 0.50 0'00 0 69 70 10. Wet Swales 71 10.a. Wet Swale #1 impervious acres draining to wet swale 10% runoff volume reduction 0;14 r, /2 10.b. Wet Swale #2 impervious acres draining to wet swale 20% runoff volume reduction 0.20 , - - 0 73 . 74 11. Site Specific BMP 75 i 1.- 17E5CR1:•- : is=1.0 :L.- r npervious acres draining to I BMP Based on site -specific continuous t Simulation modeling 0 76 Iii I ,s VOLUME REDUCTION BY PRACTICE, BMP 2 (cf)I 158,052 3 013 RR-BMP2 5/16/2012 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 CAI B C I Project Name: MSD P#: D MEP Residential Example ?9xxx-xx Pre -Construction Development Input Total Drainage Area (A) = Impervious Area = Vegetated Area = E I F I C I HI I J KI L I M INI O I P Computed By: ABC Date: Checked By: XYZ Date: 4.35 Ac. 0.00 Ac. 4.35 Ac. 5/16/12 5/18/12 THIS IS A NEW DEVELOPMENT SITE. POST -CONSTRUCTION RUNOFF SHALL MIMIC PRE-EXISTING RUNOFF TO MAXIMUM EXTENT PRACTICABLE. VA,Pre = 261,360 CF Post -Construction Dev. Input Total Drainage Area (A) = Impervious Area = Vegetated Area = VA,Post = 428,195 CF 4.35 Ac. 2.20 Ac. 2.15 Ac. Runoff Reduction BMP Group Volume (RR,,, cf) Depth (RRd, in.) * Volume Reduction, BMP 1 11549 0 Volume Reduction, BMP 2 158052 0.3 Volume Reduction, BMP 3 0 0 RR=Total BMP Volume Reduction Provided= 169601 CF 0.3 in* VA,Post - VA,Pre - RR = -2,766 CF] Total Additional Volume Reduction Needed= 0 CF * For use in curve number modification spreadsheets, for sizing downstream cetention basins. Summary Sheet 5/16/2012