SWMM-USERS Digest - 16 Apr 2012 to 20 Apr 2012 (#2012-40)

10 views

Skip to first unread message

SWMM-USERS automatic digest system

unread,

Apr 21, 2012, 12:01:53 AM4/21/12

to SWMM-...@listserv.uoguelph.ca

There are 5 messages totaling 819 lines in this issue.

Topics of the day:

1. Rain barrel routing questions (5)

**********************************************************
* To sign off, email to: list...@listserv.uoguelph.ca *
* In the body of the message type: signoff swmm-users *
**********************************************************

----------------------------------------------------------------------

Date: Fri, 20 Apr 2012 09:50:04 -0700
From: Roger Leventhal <roger.l...@GMAIL.COM>
Subject: Re: Rain barrel routing questions

I had a follow-on question to the modeling of rain barrels for flood
reduction benefits.

I am reviewing a report where the City requested an evaluation of the use
of rain barrels at homes in an urbanized watershed as a strategy to help
reduce downstream flooding. The consultants calculated the total potential
rainbarrel storage volume and then increased the initial abstraction
parameter in their model (they used HEC-HMS but I believe SWMM has an
equivalent parameter). They concluded that rain barrels would have a very
small effect on downstream flooding and therefore wasnt worth considering.

This approach seems reasonable to me but I was curious if anyone had looked
into this idea before and came to a similar conclusion or could suggest a
better way to model rain barrels or cisterns. I am sure the consultant
didn't have budget to add a storage tank at each house so they were looking
at reasonable but larger scale ways to assess the effectiveness of
micro-storage.

Any thoughts welcome, Roger

On Mon, Apr 16, 2012 at 10:25 AM, Shannon Reynolds <reyno...@gmail.com>wrote:

> Thanks for the responses!
>
> Shannon
>
> On Mon, Apr 16, 2012 at 5:59 AM, Lewis Rossman <
> Rossma...@epamail.epa.gov> wrote:
>
> > No. The flows in each stream at the current time step are combined.
> > There is no delay in the overflow from a full rain barrel.
> >
> >
> --------------------------------------------------------------------------------------
> >
> > Lewis Rossman
> > Environmental Scientist
> > Water Supply and Water Resources Division
> > U.S Environmental Protection Agency
> > email: rossma...@epa.gov
> >
> >
> >
> > From: Shannon Reynolds <reyno...@GMAIL.COM>
> > To: SWMM-...@LISTSERV.UOGUELPH.CA
> > Date: 04/13/2012 04:13 PM
> > Subject: Re: [SWMM-USERS] Rain barrel routing questions
> > Sent by: SWMM-USERS <SWMM-...@LISTSERV.UOGUELPH.CA>
> >
> >
> >
> > Thank you for the reply. One more quick question, when you say the drain
> > line flow and the overflow are combined together before routing to the
> > subcatchment outlet (or pervious area), does that mean the overflow
> > routing
> > to the outlet (or pervious area) is delayed according to the delay time
> > specified for the rain barrel?
> >
> > Cheers,
> > Shannon
> >
> > On Fri, Apr 13, 2012 at 11:32 AM, Lewis Rossman <
> > Rossma...@epamail.epa.gov> wrote:
> >
> > > Both the rain barrel overflow and the its drain line flow are combined
> > > together before routing to the subcatchment's outlet. If the "send to
> > > pervious"option is used then, again, the combined overflow and
> > > underdrain flow from the unit are sent to the subcatchment's pervious
> > > area (not to the outlet).
> > >
> > > Allowing the underdrain to have a different outlet destination is on
> > the
> > > "to do" list for a future update.
> > >
> > > Lewis Rossman
> > > Environmental Scientist
> > > Water Supply and Water Resources Division
> > > U.S Environmental Protection Agency
> > > email: rossma...@epa.gov
> > > **********************************************************
> > > * To sign off, email to: list...@listserv.uoguelph.ca *
> > > * In the body of the message type: signoff swmm-users *
> > > **********************************************************
> > >
> >
> > **********************************************************
> > * To sign off, email to: list...@listserv.uoguelph.ca *
> > * In the body of the message type: signoff swmm-users *
> > **********************************************************
> >
> >
> >
> --------------------------------------------------------------------------------------
> >
> >
> > Lewis Rossman
> > Environmental Scientist
> > Water Supply and Water Resources Division
> > U.S Environmental Protection Agency
> > email: rossma...@epa.gov
> >
> > **********************************************************
> > * To sign off, email to: list...@listserv.uoguelph.ca *
> > * In the body of the message type: signoff swmm-users *
> > **********************************************************
> >
>
> **********************************************************
> * To sign off, email to: list...@listserv.uoguelph.ca *
> * In the body of the message type: signoff swmm-users *
> **********************************************************
>

Roger Leventhal, P.E.
11 Camelot Court
Kensington, CA 94707
415-473-3249 ph

><((((º>`·. .· `·. .· `·... ><((((º> .
· `·. . , . .· `·.. ><((((º>`·. .· `·. .· `·... ><((((º>

------------------------------

Date: Fri, 20 Apr 2012 11:02:12 -0600
From: Robert Dickinson <Robert.E....@INNOVYZE.COM>
Subject: Re: Rain barrel routing questions

Hi Roger,

An interesting question,

1. A one inch rainfall on a 2000 square foot roof is about 1100 gallons, 0.9 runoff * 1/12 * 2000 ft^2 * 7.48 gallons/ft^3
2. If you had 4 250 gallon Rain barrels you would capture most of the roof runoff,
3. If you had 4 100 gallon Rain barrels you would still capture a lot of the runoff from a small or medium size storm
4,. If the storm was 10 inches you would not capture much of the roof runoff for the large event

I hope this helps or suggests something to you. SWMM 5 has a depression storage parameter which is a lot of various micro storage items and that depression storage includes initial abstraction.

Robert Dickinson
Innovyze Inc.
9340 Pontiac Drive Tel: 813-712-0664
Tampa, Florida USA 33626
robert.d...@innovyze.com
www.innovyze.com

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Roger Leventhal
Sent: Friday, April 20, 2012 12:50 PM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] Rain barrel routing questions

I had a follow-on question to the modeling of rain barrels for flood reduction benefits.

I am reviewing a report where the City requested an evaluation of the use of rain barrels at homes in an urbanized watershed as a strategy to help reduce downstream flooding. The consultants calculated the total potential rainbarrel storage volume and then increased the initial abstraction parameter in their model (they used HEC-HMS but I believe SWMM has an equivalent parameter). They concluded that rain barrels would have a very small effect on downstream flooding and therefore wasnt worth considering.

This approach seems reasonable to me but I was curious if anyone had looked into this idea before and came to a similar conclusion or could suggest a better way to model rain barrels or cisterns. I am sure the consultant didn't have budget to add a storage tank at each house so they were looking at reasonable but larger scale ways to assess the effectiveness of micro-storage.

Any thoughts welcome, Roger

On Mon, Apr 16, 2012 at 10:25 AM, Shannon Reynolds <reyno...@gmail.com>wrote:

> Thanks for the responses!
>
> Shannon
>
> On Mon, Apr 16, 2012 at 5:59 AM, Lewis Rossman <
> Rossma...@epamail.epa.gov> wrote:
>
> > No. The flows in each stream at the current time step are combined.
> > There is no delay in the overflow from a full rain barrel.
> >
> >
> ----------------------------------------------------------------------
> ----------------
> >
> > Lewis Rossman
> > Environmental Scientist
> > Water Supply and Water Resources Division U.S Environmental
> > Protection Agency
> > email: rossma...@epa.gov
> >
> >
> >
> > From: Shannon Reynolds <reyno...@GMAIL.COM>
> > To: SWMM-...@LISTSERV.UOGUELPH.CA
> > Date: 04/13/2012 04:13 PM
> > Subject: Re: [SWMM-USERS] Rain barrel routing questions
> > Sent by: SWMM-USERS <SWMM-...@LISTSERV.UOGUELPH.CA>
> >
> >
> >
> > Thank you for the reply. One more quick question, when you say the
> > drain line flow and the overflow are combined together before
> > routing to the subcatchment outlet (or pervious area), does that
> > mean the overflow routing to the outlet (or pervious area) is
> > delayed according to the delay time specified for the rain barrel?
> >
> > Cheers,
> > Shannon
> >
> > On Fri, Apr 13, 2012 at 11:32 AM, Lewis Rossman <
> > Rossma...@epamail.epa.gov> wrote:
> >
> > > Both the rain barrel overflow and the its drain line flow are
> > > combined together before routing to the subcatchment's outlet. If
> > > the "send to pervious"option is used then, again, the combined
> > > overflow and underdrain flow from the unit are sent to the
> > > subcatchment's pervious area (not to the outlet).
> > >
> > > Allowing the underdrain to have a different outlet destination is
> > > on
> > the
> > > "to do" list for a future update.
> > >
> > > Lewis Rossman
> > > Environmental Scientist
> > > Water Supply and Water Resources Division U.S Environmental
> > > Protection Agency
> > > email: rossma...@epa.gov
> > > **********************************************************
> > > * To sign off, email to: list...@listserv.uoguelph.ca *
> > > * In the body of the message type: signoff swmm-users *
> > > **********************************************************
> > >
> >
> > **********************************************************
> > * To sign off, email to: list...@listserv.uoguelph.ca *
> > * In the body of the message type: signoff swmm-users *
> > **********************************************************
> >
> >
> >
> ----------------------------------------------------------------------
> ----------------
> >
> >
> > Lewis Rossman
> > Environmental Scientist
> > Water Supply and Water Resources Division U.S Environmental
> > Protection Agency
> > email: rossma...@epa.gov
> >
> > **********************************************************
> > * To sign off, email to: list...@listserv.uoguelph.ca *
> > * In the body of the message type: signoff swmm-users *
> > **********************************************************
> >
>
> **********************************************************
> * To sign off, email to: list...@listserv.uoguelph.ca *
> * In the body of the message type: signoff swmm-users *
> **********************************************************
>

Roger Leventhal, P.E.
11 Camelot Court
Kensington, CA 94707
415-473-3249 ph

><((((º>`·. .· `·. .· `·... ><((((º> .
· `·. . , . .· `·.. ><((((º>`·. .· `·. .· `·... ><((((º>

------------------------------

Date: Fri, 20 Apr 2012 13:09:52 -0400
From: Bill Lucas <wlu...@INTEGRATEDLAND.COM>
Subject: Re: Rain barrel routing questions

Bob Pitt did a study on rain barrels using WinSLAMM. I believe it is in the
2010 EWRI Proceedings. Effects on CSOs were only noted if around 20 barrels
were used per home. SWMM would have similar conclusions. So the conclusions
of your consultants are sound.

Bob instead proposed storage tanks which would work, but then you need the
appropriate demand curve, and/or RTC that can draw down the storage before
events. This is an emerging field in RWH.

Rain barrels are good for citizen participation, in that 30% of the adopters
also installed rain gardens. Those were then quite effective in lowering
CSOs. However, I tend to think that they would have less effect on events
with ARIs over 2-years.

BTW, note that Bob Dickinson was putting in the equivalent of 18 rain
barrels at 55 gallons per. So conclusions are similar.

Bill Lucas

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Roger
Leventhal
Sent: Friday, April 20, 2012 12:50 PM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] Rain barrel routing questions

I had a follow-on question to the modeling of rain barrels for flood
reduction benefits.

Any thoughts welcome, Roger

On Mon, Apr 16, 2012 at 10:25 AM, Shannon Reynolds
<reyno...@gmail.com>wrote:

> Thanks for the responses!
>
> Shannon
>
> On Mon, Apr 16, 2012 at 5:59 AM, Lewis Rossman <
> Rossma...@epamail.epa.gov> wrote:
>
> > No. The flows in each stream at the current time step are combined.
> > There is no delay in the overflow from a full rain barrel.
> >
> >
>
----------------------------------------------------------------------------
----------
> >
> > Lewis Rossman
> > Environmental Scientist
> > Water Supply and Water Resources Division
> > U.S Environmental Protection Agency
> > email: rossma...@epa.gov
> >
> >
> >
> > From: Shannon Reynolds <reyno...@GMAIL.COM>
> > To: SWMM-...@LISTSERV.UOGUELPH.CA
> > Date: 04/13/2012 04:13 PM
> > Subject: Re: [SWMM-USERS] Rain barrel routing questions
> > Sent by: SWMM-USERS <SWMM-...@LISTSERV.UOGUELPH.CA>
> >
> >
> >
> > Thank you for the reply. One more quick question, when you say the drain
> > line flow and the overflow are combined together before routing to the
> > subcatchment outlet (or pervious area), does that mean the overflow
> > routing
> > to the outlet (or pervious area) is delayed according to the delay time
> > specified for the rain barrel?
> >
> > Cheers,
> > Shannon
> >
> > On Fri, Apr 13, 2012 at 11:32 AM, Lewis Rossman <
> > Rossma...@epamail.epa.gov> wrote:
> >
> > > Both the rain barrel overflow and the its drain line flow are combined
> > > together before routing to the subcatchment's outlet. If the "send to
> > > pervious"option is used then, again, the combined overflow and
> > > underdrain flow from the unit are sent to the subcatchment's pervious
> > > area (not to the outlet).
> > >
> > > Allowing the underdrain to have a different outlet destination is on
> > the
> > > "to do" list for a future update.
> > >
> > > Lewis Rossman
> > > Environmental Scientist
> > > Water Supply and Water Resources Division
> > > U.S Environmental Protection Agency
> > > email: rossma...@epa.gov
> > > **********************************************************
> > > * To sign off, email to: list...@listserv.uoguelph.ca *
> > > * In the body of the message type: signoff swmm-users *
> > > **********************************************************
> > >
> >
> > **********************************************************
> > * To sign off, email to: list...@listserv.uoguelph.ca *
> > * In the body of the message type: signoff swmm-users *
> > **********************************************************
> >
> >
> >
>
----------------------------------------------------------------------------
----------
> >
> >
> > Lewis Rossman
> > Environmental Scientist
> > Water Supply and Water Resources Division
> > U.S Environmental Protection Agency
> > email: rossma...@epa.gov
> >
> > **********************************************************
> > * To sign off, email to: list...@listserv.uoguelph.ca *
> > * In the body of the message type: signoff swmm-users *
> > **********************************************************
> >
>
> **********************************************************
> * To sign off, email to: list...@listserv.uoguelph.ca *
> * In the body of the message type: signoff swmm-users *
> **********************************************************
>

Roger Leventhal, P.E.
11 Camelot Court
Kensington, CA 94707
415-473-3249 ph

><((((º>`·. .· `·. .· `·... ><((((º> .
· `·. . , . .· `·.. ><((((º>`·. .· `·. .· `·... ><((((º>

------------------------------

Date: Fri, 20 Apr 2012 17:26:57 +0000
From: William Frost <Willia...@KCI.COM>
Subject: Re: Rain barrel routing questions

I would concur with the consultant's conclusion. Given a 50 gal rain barrel at each downspout and ~600 SF of roof per downspout, rain barrels will be full after the first ~0.15" of rain, after which they'll be bypassed. They just lop off the lead part of the hydrograph, not the peak. The rainfall that causes flooding will occur after the barrel is full.

For a SWMM model, I'd increase the depression storage coefficient to match what is expected to be captured by the rain barrels. First calculate the volume captured by the rainbarrels, then take that volume and apply it over the whole catchment impervious area to get the depth of depression storage.

Bill Frost, PE, D.WRE
KCI Technologies, Inc.
Sparks, MD

I had a follow-on question to the modeling of rain barrels for flood
reduction benefits.

Any thoughts welcome, Roger

On Mon, Apr 16, 2012 at 10:25 AM, Shannon Reynolds <reyno...@gmail.com>wrote:

Roger Leventhal, P.E.
11 Camelot Court
Kensington, CA 94707
415-473-3249 ph

><((((º>`·. .· `·. .· `·... ><((((º> .
· `·. . , . .· `·.. ><((((º>`·. .· `·. .· `·... ><((((º>

------------------------------

Date: Fri, 20 Apr 2012 18:29:19 +0000
From: Andrew Potts <Andrew...@CH2M.COM>
Subject: Re: Rain barrel routing questions

There has been good discussion on the impact of the rain barrels by themselves, but I think this may be missing a more important point: where the rain barrels overflow to. If someone disconnects a roof leader to install a rain barrel, and the overflow now goes to their yard instead of being more directly connected to the drainage system, that can have a huge benefit even during large storms. People may argue that this is not really a benefit of the rain barrels, but I see it as an incidental benefit. Therefore when I model the benefits of rain barrels, I usually look at the combined benefit (of the rain barrels and a portion of the overflows being disconnected) and of course make that clear in the documentation. I know some advocates refer to rain barrels as the gateway BMP...

Andy

Andrew Potts, P.E., LEED AP, CPESC
Senior Project Technologist
Water Resources

CH2M HILL
1717 Arch Street - Suite 4400
Philadelphia, PA 19103
Phone: 215.640.9033
www.ch2mhill.com

I had a follow-on question to the modeling of rain barrels for flood
reduction benefits.

Any thoughts welcome, Roger

On Mon, Apr 16, 2012 at 10:25 AM, Shannon Reynolds <reyno...@gmail.com>wrote:

Roger Leventhal, P.E.
11 Camelot Court
Kensington, CA 94707
415-473-3249 ph

><((((º>`·. .· `·. .· `·... ><((((º> .
· `·. . , . .· `·.. ><((((º>`·. .· `·. .· `·... ><((((º>

------------------------------

End of SWMM-USERS Digest - 16 Apr 2012 to 20 Apr 2012 (#2012-40)
****************************************************************

Reply all

Reply to author

Forward

0 new messages