SWMM-USERS Digest - 7 Feb 2012 to 8 Feb 2012 (#2012-13)

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There are 7 messages totaling 1115 lines in this issue.

Topics of the day:

1. FW: Water Quality EMC- Calgary (6)
2. FW: Notification of BASINS evaluation

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Date: Wed, 8 Feb 2012 09:33:55 -0700
From: Osprey Engineering <ospr...@GMAIL.COM>
Subject: Re: FW: Water Quality EMC- Calgary

Hi Bill, Mike et al.,

From a local practitioner, Alberta's storm water TSS guidelines are
structured from particle size distributions - i.e. the goal is to remove a
certain percentage (85%) of a certain particle size fraction (generally 50
or 75 µm or larger). Calgary does have a particle size distribution that is
used for modeling the effectiveness of TSS removal - its Table 7-3 (p 290)
in its Stormwater Management and Design Manual (2011) (URL
http://www.calgary.ca/PDA/DBA/Documents/urban_development/bulletins/2011-sto
rmwater-management-and-Design.pdf). These appear to have been revised from
the previous values that had been used for about 20 years. Note also that
QHM or QUALHYMO were overwhelmingly the models of choice for WQ simulations
in Calgary and area. So the confusion of using SWMM for water quality is not
inconsequential for the City.

Also note that the City of Calgary's Stormwater Management and Design Manual
(2011) does have EMCs for the major pollutants listed (Table 7-2, p 284).

It must be noted that, in general, there are no provincial limits for
pathogens, N and P in stormwater except in specific areas (e.g. areas
tributary to certain irrigation districts).

Michael A. Kitchen, P.Eng.
Osprey Engineering Inc.
Black Diamond, Alberta, Canada

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of
Gregory, Mike (Canada)
Sent: Tuesday, February 07, 2012 7:50 AM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

If you want to make any credible estimates of particulate removal, then
you'll need to describe the suspended particles with characteristic curves
(particle size distributions) rather than a single EMC. I'm talking about
tanks and ponds here, I agree with Bill on differences with LID.

In SWMM5 you can break up the TSS particle size distribution by settling
velocity characteristics (say, from TSS1 = 20% finest fraction to TSS5 = 20%
coarsest fraction). SWMM5 can route and remove each of these "pollutants"
individually. Composite results using long-term rainfall will indicate
average annual % removal, and expected volume to be dredged (using bulk
densities by fraction, of course).

Regards,
mike g.

Michael A. Gregory
AECOM - Kitchener, Canada

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Bill
Lucas
Sent: Monday, February 06, 2012 8:04 PM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

Hello Bill,

That is because there are no coefficients. Unlike ponds that use good old
Stokes Law, LID practices are primarily infiltrative, with essentially no
discharge until they cannot handle any more runoff. Then they discharge
with essentially minimal attenuation, or even export stressors, as is often
the case of pathogens.

However, if underdrain flows are somehow segregated, most stressors in those
flows are greatly attenuated, so one could use an irreducible concentration
approach. For instance, bioretention systems will typically discharge TSS in
the range of 2-10 mg/l. Dissolved P will vary depending upon load, media
and age of the system, so no good answer there. Dissolved N will vary even
more, depending upon retention time. I am hoping that Lew will put together
a module to compute that one of these days.

So the issue comes down to segregating the annual surface flows from
underdrain flows. While SWMM-LID does not do this explicitly in terms of
routing, you can set up the LID file to be queried so as to obtain this
data. You can then apply the "appropriate" EMCs to the volumes filtered and
those bypassed to get the effective mass loads delivered via each pathway.
You can go to the literature for the appropriate EMC values. I strongly
recommend this approach.

Frankly, if you want to model a rain garden by its lonesome, I think the
RECARGA or SPAW models do as good a job as any model in the public domain.
Their unsaturated flow and ET algorithms are quite realistic. SWMM is a tool
better used for routing.

If you need to segregate underdrain flows from bypass flows in the routing
model, as is often needed for CSO modeling, then you have to get a little
sneaky. I do it using a dummy storage node, with an underdrain formulated
to match the SWMM parameters (this takes a little doing), and a bypass weir
to allow overflows to stay in the conventional drainage system. Pretty
simple, but now you have added a node and two links to each catchment, so
kind of cumbersome.

At the end of the current day, we still have a quite primitive understanding
of how LID works in terms of biogeochemistry of stressor transformations and
removals. However, we are getting there in terms of the hydrology. But we
still have a ways to go there, so there is still plenty of work for Lew :)

Bill L.

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Bill
Sent: Monday, February 06, 2012 7:12 PM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: [SWMM-USERS] FW: Water Quality EMC- Calgary

Hello swmm-users:

A consultant working for the City of Calgary has been asked to size and
design a rain garden and is considering using SWMM to carry out the water
quality and long term simulation analyses. However the City has never used
SWMM for such analyses and therefore has not yet developed an EMC
coefficient to model TSS. Can anyone commend EMC coefficients for
Calgary/Alberta or a way to find appropriate EMC coefficients? If these
criteria are not available then we would appreciate knowing that too.

Regards, Bill James

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

Date: Wed, 8 Feb 2012 09:55:58 -0700
From: Ben Urbonas - Personal <b...@URBONAS.ORG>
Subject: Re: FW: Water Quality EMC- Calgary

Apparently Calgary has moved the reference you included and the URL address
does not take you to the table you refer.

Ben Urbonas
(H & F) 303-765-0155
(M) 303-728-4449

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of
Osprey Engineering
Sent: Wednesday, February 08, 2012 9:34 AM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

Hi Bill, Mike et al.,

Also note that the City of Calgary's Stormwater Management and Design Manual
(2011) does have EMCs for the major pollutants listed (Table 7-2, p 284).

It must be noted that, in general, there are no provincial limits for
pathogens, N and P in stormwater except in specific areas (e.g. areas
tributary to certain irrigation districts).

Michael A. Kitchen, P.Eng.
Osprey Engineering Inc.
Black Diamond, Alberta, Canada

Regards,
mike g.

Michael A. Gregory
AECOM - Kitchener, Canada

Hello Bill,

Bill L.

Hello swmm-users:

Regards, Bill James

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

Date: Wed, 8 Feb 2012 09:00:49 -0800
From: Jay Heiman <Jayh...@CIVILSOLUTIONS.ORG>
Subject: Re: FW: Water Quality EMC- Calgary

Ben
The link is broken (literally) onto 2 lines.
Put back together, it works.

Jay Heiman, PE, CFM
Civil Engineering Solutions, Inc.
590 E Street
Lincoln, CA 95648
916-645-5700 Voice
916-645-5706 Fax
916-599-6268 Cell
jayh...@civilsolutions.com

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Ben Urbonas - Personal
Sent: Wednesday, February 08, 2012 08:56
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

Apparently Calgary has moved the reference you included and the URL address does not take you to the table you refer.

Ben Urbonas
(H & F) 303-765-0155
(M) 303-728-4449

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Osprey Engineering
Sent: Wednesday, February 08, 2012 9:34 AM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

Hi Bill, Mike et al.,

From a local practitioner, Alberta's storm water TSS guidelines are structured from particle size distributions - i.e. the goal is to remove a certain percentage (85%) of a certain particle size fraction (generally 50 or 75 µm or larger). Calgary does have a particle size distribution that is used for modeling the effectiveness of TSS removal - its Table 7-3 (p 290) in its Stormwater Management and Design Manual (2011) (URL http://www.calgary.ca/PDA/DBA/Documents/urban_development/bulletins/2011-sto
rmwater-management-and-Design.pdf). These appear to have been revised from the previous values that had been used for about 20 years. Note also that QHM or QUALHYMO were overwhelmingly the models of choice for WQ simulations in Calgary and area. So the confusion of using SWMM for water quality is not inconsequential for the City.

Also note that the City of Calgary's Stormwater Management and Design Manual
(2011) does have EMCs for the major pollutants listed (Table 7-2, p 284).

It must be noted that, in general, there are no provincial limits for pathogens, N and P in stormwater except in specific areas (e.g. areas tributary to certain irrigation districts).

Michael A. Kitchen, P.Eng.
Osprey Engineering Inc.
Black Diamond, Alberta, Canada

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Gregory, Mike (Canada)
Sent: Tuesday, February 07, 2012 7:50 AM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

If you want to make any credible estimates of particulate removal, then you'll need to describe the suspended particles with characteristic curves (particle size distributions) rather than a single EMC. I'm talking about tanks and ponds here, I agree with Bill on differences with LID.

In SWMM5 you can break up the TSS particle size distribution by settling velocity characteristics (say, from TSS1 = 20% finest fraction to TSS5 = 20% coarsest fraction). SWMM5 can route and remove each of these "pollutants"
individually. Composite results using long-term rainfall will indicate average annual % removal, and expected volume to be dredged (using bulk densities by fraction, of course).

Regards,
mike g.

Michael A. Gregory
AECOM - Kitchener, Canada

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Bill Lucas
Sent: Monday, February 06, 2012 8:04 PM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

Hello Bill,

That is because there are no coefficients. Unlike ponds that use good old Stokes Law, LID practices are primarily infiltrative, with essentially no discharge until they cannot handle any more runoff. Then they discharge with essentially minimal attenuation, or even export stressors, as is often the case of pathogens.

However, if underdrain flows are somehow segregated, most stressors in those flows are greatly attenuated, so one could use an irreducible concentration approach. For instance, bioretention systems will typically discharge TSS in the range of 2-10 mg/l. Dissolved P will vary depending upon load, media and age of the system, so no good answer there. Dissolved N will vary even more, depending upon retention time. I am hoping that Lew will put together a module to compute that one of these days.

So the issue comes down to segregating the annual surface flows from underdrain flows. While SWMM-LID does not do this explicitly in terms of routing, you can set up the LID file to be queried so as to obtain this data. You can then apply the "appropriate" EMCs to the volumes filtered and those bypassed to get the effective mass loads delivered via each pathway.
You can go to the literature for the appropriate EMC values. I strongly recommend this approach.

Frankly, if you want to model a rain garden by its lonesome, I think the RECARGA or SPAW models do as good a job as any model in the public domain.
Their unsaturated flow and ET algorithms are quite realistic. SWMM is a tool better used for routing.

If you need to segregate underdrain flows from bypass flows in the routing model, as is often needed for CSO modeling, then you have to get a little sneaky. I do it using a dummy storage node, with an underdrain formulated to match the SWMM parameters (this takes a little doing), and a bypass weir to allow overflows to stay in the conventional drainage system. Pretty simple, but now you have added a node and two links to each catchment, so kind of cumbersome.

At the end of the current day, we still have a quite primitive understanding of how LID works in terms of biogeochemistry of stressor transformations and removals. However, we are getting there in terms of the hydrology. But we still have a ways to go there, so there is still plenty of work for Lew :)

Bill L.

Hello swmm-users:

A consultant working for the City of Calgary has been asked to size and design a rain garden and is considering using SWMM to carry out the water quality and long term simulation analyses. However the City has never used SWMM for such analyses and therefore has not yet developed an EMC coefficient to model TSS. Can anyone commend EMC coefficients for Calgary/Alberta or a way to find appropriate EMC coefficients? If these criteria are not available then we would appreciate knowing that too.

Regards, Bill James

-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2012.0.1913 / Virus Database: 2109/4779 - Release Date: 02/01/12 Internal Virus Database is out of date.

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

Date: Wed, 8 Feb 2012 17:13:54 +0000
From: "Gregory, Mike (Canada)" <Mike.G...@AECOM.COM>
Subject: Re: FW: Water Quality EMC- Calgary

I'm glad municipalities are starting to recognize that percent removal is ambiguous without specifying equiv particle size fraction. Just a caution though, that the PSD for sediment collected in runoff at the source (i.e., street gutter or other easy-access grab sample location) is very very different compared to PSD collected from sample taken from pond inlet pipe. Design using streetwise PSD (say D50 = 80 microns) will indicate your pond is highly effective at TSS removal**. Obviously that same design will not be nearly as effective at treating the pond-clogging sediments that get washed thru the collection system (i.e., sample PSD with D50 = 8 microns).

**[cynical comment, sans smiley] and, by extension, also effective at dissolved nutrient removal, because everyone *knows* that TP is always 45% of TSS.

Regards,
mike g.

Michael A. Gregory
AECOM - Kitchener, Canada

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Jay Heiman
Sent: Wednesday, February 08, 2012 12:01 PM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

Ben
The link is broken (literally) onto 2 lines.
Put back together, it works.

Jay Heiman, PE, CFM
Civil Engineering Solutions, Inc.
590 E Street
Lincoln, CA 95648
916-645-5700 Voice
916-645-5706 Fax
916-599-6268 Cell
jayh...@civilsolutions.com

Apparently Calgary has moved the reference you included and the URL address does not take you to the table you refer.

Ben Urbonas
(H & F) 303-765-0155
(M) 303-728-4449

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Osprey Engineering
Sent: Wednesday, February 08, 2012 9:34 AM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

Hi Bill, Mike et al.,

From a local practitioner, Alberta's storm water TSS guidelines are structured from particle size distributions - i.e. the goal is to remove a certain percentage (85%) of a certain particle size fraction (generally 50 or 75 µm or larger). Calgary does have a particle size distribution that is used for modeling the effectiveness of TSS removal - its Table 7-3 (p 290) in its Stormwater Management and Design Manual (2011) (URL http://www.calgary.ca/PDA/DBA/Documents/urban_development/bulletins/2011-sto
rmwater-management-and-Design.pdf). These appear to have been revised from the previous values that had been used for about 20 years. Note also that QHM or QUALHYMO were overwhelmingly the models of choice for WQ simulations in Calgary and area. So the confusion of using SWMM for water quality is not inconsequential for the City.

Also note that the City of Calgary's Stormwater Management and Design Manual
(2011) does have EMCs for the major pollutants listed (Table 7-2, p 284).

It must be noted that, in general, there are no provincial limits for pathogens, N and P in stormwater except in specific areas (e.g. areas tributary to certain irrigation districts).

Michael A. Kitchen, P.Eng.
Osprey Engineering Inc.
Black Diamond, Alberta, Canada

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Gregory, Mike (Canada)
Sent: Tuesday, February 07, 2012 7:50 AM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

If you want to make any credible estimates of particulate removal, then you'll need to describe the suspended particles with characteristic curves (particle size distributions) rather than a single EMC. I'm talking about tanks and ponds here, I agree with Bill on differences with LID.

In SWMM5 you can break up the TSS particle size distribution by settling velocity characteristics (say, from TSS1 = 20% finest fraction to TSS5 = 20% coarsest fraction). SWMM5 can route and remove each of these "pollutants"
individually. Composite results using long-term rainfall will indicate average annual % removal, and expected volume to be dredged (using bulk densities by fraction, of course).

Regards,
mike g.

Michael A. Gregory
AECOM - Kitchener, Canada

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Bill Lucas
Sent: Monday, February 06, 2012 8:04 PM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

Hello Bill,

That is because there are no coefficients. Unlike ponds that use good old Stokes Law, LID practices are primarily infiltrative, with essentially no discharge until they cannot handle any more runoff. Then they discharge with essentially minimal attenuation, or even export stressors, as is often the case of pathogens.

However, if underdrain flows are somehow segregated, most stressors in those flows are greatly attenuated, so one could use an irreducible concentration approach. For instance, bioretention systems will typically discharge TSS in the range of 2-10 mg/l. Dissolved P will vary depending upon load, media and age of the system, so no good answer there. Dissolved N will vary even more, depending upon retention time. I am hoping that Lew will put together a module to compute that one of these days.

So the issue comes down to segregating the annual surface flows from underdrain flows. While SWMM-LID does not do this explicitly in terms of routing, you can set up the LID file to be queried so as to obtain this data. You can then apply the "appropriate" EMCs to the volumes filtered and those bypassed to get the effective mass loads delivered via each pathway.
You can go to the literature for the appropriate EMC values. I strongly recommend this approach.

Frankly, if you want to model a rain garden by its lonesome, I think the RECARGA or SPAW models do as good a job as any model in the public domain.
Their unsaturated flow and ET algorithms are quite realistic. SWMM is a tool better used for routing.

If you need to segregate underdrain flows from bypass flows in the routing model, as is often needed for CSO modeling, then you have to get a little sneaky. I do it using a dummy storage node, with an underdrain formulated to match the SWMM parameters (this takes a little doing), and a bypass weir to allow overflows to stay in the conventional drainage system. Pretty simple, but now you have added a node and two links to each catchment, so kind of cumbersome.

At the end of the current day, we still have a quite primitive understanding of how LID works in terms of biogeochemistry of stressor transformations and removals. However, we are getting there in terms of the hydrology. But we still have a ways to go there, so there is still plenty of work for Lew :)

Bill L.

Hello swmm-users:

A consultant working for the City of Calgary has been asked to size and design a rain garden and is considering using SWMM to carry out the water quality and long term simulation analyses. However the City has never used SWMM for such analyses and therefore has not yet developed an EMC coefficient to model TSS. Can anyone commend EMC coefficients for Calgary/Alberta or a way to find appropriate EMC coefficients? If these criteria are not available then we would appreciate knowing that too.

Regards, Bill James

-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2012.0.1913 / Virus Database: 2109/4779 - Release Date: 02/01/12 Internal Virus Database is out of date.

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

Date: Wed, 8 Feb 2012 17:19:02 +0000
From: "Gregory, Mike (Canada)" <Mike.G...@AECOM.COM>
Subject: Re: FW: Water Quality EMC- Calgary

Pardon my opinions, but I meant to say "downstream watercourse-clogging sediments" - the smaller the particle the more likely the pond will pass that thru without treatment.

Regards,
mike g.

Michael A. Gregory
AECOM - Kitchener, Canada

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Gregory, Mike (Canada)
Sent: Wednesday, February 08, 2012 12:14 PM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

**[cynical comment, sans smiley] and, by extension, also effective at dissolved nutrient removal, because everyone *knows* that TP is always 45% of TSS.

Regards,
mike g.

Michael A. Gregory
AECOM - Kitchener, Canada

Ben
The link is broken (literally) onto 2 lines.
Put back together, it works.

Jay Heiman, PE, CFM
Civil Engineering Solutions, Inc.
590 E Street
Lincoln, CA 95648
916-645-5700 Voice
916-645-5706 Fax
916-599-6268 Cell
jayh...@civilsolutions.com

Apparently Calgary has moved the reference you included and the URL address does not take you to the table you refer.

Ben Urbonas
(H & F) 303-765-0155
(M) 303-728-4449

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Osprey Engineering
Sent: Wednesday, February 08, 2012 9:34 AM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

Hi Bill, Mike et al.,

From a local practitioner, Alberta's storm water TSS guidelines are structured from particle size distributions - i.e. the goal is to remove a certain percentage (85%) of a certain particle size fraction (generally 50 or 75 µm or larger). Calgary does have a particle size distribution that is used for modeling the effectiveness of TSS removal - its Table 7-3 (p 290) in its Stormwater Management and Design Manual (2011) (URL http://www.calgary.ca/PDA/DBA/Documents/urban_development/bulletins/2011-sto
rmwater-management-and-Design.pdf). These appear to have been revised from the previous values that had been used for about 20 years. Note also that QHM or QUALHYMO were overwhelmingly the models of choice for WQ simulations in Calgary and area. So the confusion of using SWMM for water quality is not inconsequential for the City.

Also note that the City of Calgary's Stormwater Management and Design Manual
(2011) does have EMCs for the major pollutants listed (Table 7-2, p 284).

It must be noted that, in general, there are no provincial limits for pathogens, N and P in stormwater except in specific areas (e.g. areas tributary to certain irrigation districts).

Michael A. Kitchen, P.Eng.
Osprey Engineering Inc.
Black Diamond, Alberta, Canada

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Gregory, Mike (Canada)
Sent: Tuesday, February 07, 2012 7:50 AM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

If you want to make any credible estimates of particulate removal, then you'll need to describe the suspended particles with characteristic curves (particle size distributions) rather than a single EMC. I'm talking about tanks and ponds here, I agree with Bill on differences with LID.

In SWMM5 you can break up the TSS particle size distribution by settling velocity characteristics (say, from TSS1 = 20% finest fraction to TSS5 = 20% coarsest fraction). SWMM5 can route and remove each of these "pollutants"
individually. Composite results using long-term rainfall will indicate average annual % removal, and expected volume to be dredged (using bulk densities by fraction, of course).

Regards,
mike g.

Michael A. Gregory
AECOM - Kitchener, Canada

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Bill Lucas
Sent: Monday, February 06, 2012 8:04 PM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

Hello Bill,

That is because there are no coefficients. Unlike ponds that use good old Stokes Law, LID practices are primarily infiltrative, with essentially no discharge until they cannot handle any more runoff. Then they discharge with essentially minimal attenuation, or even export stressors, as is often the case of pathogens.

However, if underdrain flows are somehow segregated, most stressors in those flows are greatly attenuated, so one could use an irreducible concentration approach. For instance, bioretention systems will typically discharge TSS in the range of 2-10 mg/l. Dissolved P will vary depending upon load, media and age of the system, so no good answer there. Dissolved N will vary even more, depending upon retention time. I am hoping that Lew will put together a module to compute that one of these days.

So the issue comes down to segregating the annual surface flows from underdrain flows. While SWMM-LID does not do this explicitly in terms of routing, you can set up the LID file to be queried so as to obtain this data. You can then apply the "appropriate" EMCs to the volumes filtered and those bypassed to get the effective mass loads delivered via each pathway.
You can go to the literature for the appropriate EMC values. I strongly recommend this approach.

Frankly, if you want to model a rain garden by its lonesome, I think the RECARGA or SPAW models do as good a job as any model in the public domain.
Their unsaturated flow and ET algorithms are quite realistic. SWMM is a tool better used for routing.

If you need to segregate underdrain flows from bypass flows in the routing model, as is often needed for CSO modeling, then you have to get a little sneaky. I do it using a dummy storage node, with an underdrain formulated to match the SWMM parameters (this takes a little doing), and a bypass weir to allow overflows to stay in the conventional drainage system. Pretty simple, but now you have added a node and two links to each catchment, so kind of cumbersome.

At the end of the current day, we still have a quite primitive understanding of how LID works in terms of biogeochemistry of stressor transformations and removals. However, we are getting there in terms of the hydrology. But we still have a ways to go there, so there is still plenty of work for Lew :)

Bill L.

Hello swmm-users:

A consultant working for the City of Calgary has been asked to size and design a rain garden and is considering using SWMM to carry out the water quality and long term simulation analyses. However the City has never used SWMM for such analyses and therefore has not yet developed an EMC coefficient to model TSS. Can anyone commend EMC coefficients for Calgary/Alberta or a way to find appropriate EMC coefficients? If these criteria are not available then we would appreciate knowing that too.

Regards, Bill James

-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2012.0.1913 / Virus Database: 2109/4779 - Release Date: 02/01/12 Internal Virus Database is out of date.

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

Date: Wed, 8 Feb 2012 10:20:01 -0700
From: Ben Urbonas - Personal <b...@URBONAS.ORG>
Subject: Re: FW: Water Quality EMC- Calgary

Thank you for the clarification. It does work.

Ben Urbonas
(H & F) 303-765-0155
(M) 303-728-4449

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Jay
Heiman
Sent: Wednesday, February 08, 2012 10:01 AM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

Ben
The link is broken (literally) onto 2 lines.
Put back together, it works.

Jay Heiman, PE, CFM
Civil Engineering Solutions, Inc.
590 E Street
Lincoln, CA 95648
916-645-5700 Voice
916-645-5706 Fax
916-599-6268 Cell
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-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of Ben
Urbonas - Personal
Sent: Wednesday, February 08, 2012 08:56
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] FW: Water Quality EMC- Calgary

Apparently Calgary has moved the reference you included and the URL address
does not take you to the table you refer.

Ben Urbonas
(H & F) 303-765-0155
(M) 303-728-4449

Hi Bill, Mike et al.,

From a local practitioner, Alberta's storm water TSS guidelines are
structured from particle size distributions - i.e. the goal is to remove a
certain percentage (85%) of a certain particle size fraction (generally 50
or 75 µm or larger). Calgary does have a particle size distribution that is
used for modeling the effectiveness of TSS removal - its Table 7-3 (p 290)
in its Stormwater Management and Design Manual (2011) (URL
http://www.calgary.ca/PDA/DBA/Documents/urban_development/bulletins/2011-sto
rmwater-management-and-Design.pdf ). These appear to have been revised from
the previous values that had been used for about 20 years. Note also that
QHM or QUALHYMO were overwhelmingly the models of choice for WQ simulations
in Calgary and area. So the confusion of using SWMM for water quality is not
inconsequential for the City.

Also note that the City of Calgary's Stormwater Management and Design Manual
(2011) does have EMCs for the major pollutants listed (Table 7-2, p 284).

It must be noted that, in general, there are no provincial limits for
pathogens, N and P in stormwater except in specific areas (e.g. areas
tributary to certain irrigation districts).

Michael A. Kitchen, P.Eng.
Osprey Engineering Inc.
Black Diamond, Alberta, Canada

Regards,
mike g.

Michael A. Gregory
AECOM - Kitchener, Canada

Hello Bill,

Bill L.

Hello swmm-users:

Regards, Bill James

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

Date: Wed, 8 Feb 2012 14:16:41 -0500
From: Bill <bi...@CHIWATER.COM>
Subject: FW: Notification of BASINS evaluation

Forwarded post - please do not reply to the list or to Bill James.

The EPA's Office of Water is evaluating whether to phase out financial
and technical support for BASINS, the environmental analysis system that
integrates a geographical information system (GIS), national watershed
data, and state-of-the-art environmental assessment and modeling tools.
As part of this evaluation we are gathering information about who uses
it, for which purposes, whether there should be modifications in its
direction and/or support, and what the impacts would be on current users
if the Office of Water no longer supports it. This evaluation has
become particularly important in the face of shrinking federal budgets.

Because you have expressed interest in BASINS in the past (e.g., as a
workshop participant or BASINS listserv subscriber), we would greatly
appreciate your input to this process.

If you would like to participate, please visit
<https://www.surveymonkey.com/s/BASINSuse_survey>
https://www.surveymonkey.com/s/BASINSuse_survey. We estimate it will
take fewer than 10 minutes to answer the questions. Your response will
be used only for purposes of the survey.

The survey will be available for the next 2 weeks, until midnight on
Friday, February 10. Please feel free to forward this email or link to
other interested parties.

Thank you for your time and interest in BASINS.

_________________________________________________
Lisa Larimer, P.E.
Team Leader, Modeling and Technical Assisstance Team
202-566-1017

U.S. Environmental Protection Agency | Washington, DC
Office of Water | Water Quality Standards program
water.epa.gov/scitech/swguidance

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

End of SWMM-USERS Digest - 7 Feb 2012 to 8 Feb 2012 (#2012-13)
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