SWMM-USERS Digest - 6 Feb 2012 to 7 Feb 2012 (#2012-12)

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Feb 8, 2012, 12:00:04 AM2/8/12

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There are 2 messages totaling 386 lines in this issue.

Topics of the day:

1. Pumping in SWMM - timeseries reporting
2. FW: Water Quality EMC- Calgary

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Date: Tue, 7 Feb 2012 15:49:22 +1000
From: Nick Andrewes <Nick.A...@GHD.COM>
Subject: Re: Pumping in SWMM - timeseries reporting

Hi Joseph,

Thanks very much for your contribution. What you are saying makes sense
and would appear to explain the extremely high number of pump start ups
reported during the simulation. I'm in the process of running a test
simulation to confirm.

Thanks again.

Nick

Nick Andrewes
Environmental Engineer | Waterways & Stormwater Service Group

Please consider the environment before printing this email

From:
"Pang, Joseph" <Josep...@SEATTLE.GOV>
To:
SWMM-...@LISTSERV.UOGUELPH.CA
Date:
07/02/2012 10:24 AM
Subject:
Re: Pumping in SWMM - timeseries reporting
Sent by:
SWMM-USERS <SWMM-...@LISTSERV.UOGUELPH.CA>

See code in link_setTargetSetting(int j) and this should help you to
figure out what's going on...

if ( Pump[k].yOff > 0.0 && //(5.0.010 - LR)
Link[j].setting > 0.0 && //(5.0.010 - LR)
Node[n1].newDepth < Pump[k].yOff ) Link[j].targetSetting =
0.0; //(5.0.010 - LR)
if ( Pump[k].yOn > 0.0 && //(5.0.010 - LR)
Link[j].setting == 0.0 && //(5.0.010 - LR)
Node[n1].newDepth > Pump[k].yOn ) Link[j].targetSetting =
1.0; //(5.0.010 - LR)

link_setTargetSetting(int j) is the only place where I can find reference
of Pump[].yOn and Pump[].yOff. If I understand the code correctly and
haven't missed anything in the code, I think this is what it does..

Condition 1: If Shut-off Depth > 0 and Pump is on and wet-well level <
shut-off depth, then pump is shut off.
Condition 2: If Start-up depth > 0 and Pump is off and wet-well level >
start-up depth, then pump is turned on.

So if you've a shut-off depth greater than start-up depth and your wet
well is empty initially, your pump is turned on once the wet-well level is
above start-up depth (Condition 1), but then it will be shut off probably
in the next time step because it will have satisfied Condition 2 in the
next time step.

I think the shut-off depth is used to model operation of pump station with
the shut-off depth being lower than the start-up depth which is usually
the case for setting pump station on/off level under normal operation.

If you find your wet-well level reduces while your pump is not pumping,
check whether your wet-well storage node is flooding or not. If you use
storage node to model wet-well, ponded area function is not applicable to
storage node and thus all water that floods a storage node is lost from
the system.

Joseph P.

-----Original Message-----
From: SWMM-USERS [mailto:SWMM-...@LISTSERV.UOGUELPH.CA] On Behalf Of
Nick Andrewes
Sent: Monday, February 06, 2012 2:20 PM
To: SWMM-...@LISTSERV.UOGUELPH.CA
Subject: Re: [SWMM-USERS] Pumping in SWMM - timeseries reporting

Hi Rob,

That could be a major problem! I was under the impression that if I
wanted to pump between say 1m depth and 1.5 m depth the start up depth was
the lower of the two numbers. However I guess I was thinking about it
from the perspective of the incoming hydrograph entering the storage and
raising the water levels.

I'll certainly give it a go but what baffles me is that the pumps seem to
be working correctly with the existing startup depth/ shutoff depth setup
for most of the time series.

Thanks

Nick

Nick Andrewes
Environmental Engineer | Waterways & Stormwater Service Group

Please consider the environment before printing this email

From:
Rob James <r...@CHIWATER.COM>
To:
SWMM-...@LISTSERV.UOGUELPH.CA
Date:
06/02/2012 10:49 PM
Subject:
Re: Pumping in SWMM - timeseries reporting Sent by:
SWMM-USERS <SWMM-...@LISTSERV.UOGUELPH.CA>

Hi Nick,

Not sure if this is a typo, but startup depth should be greater than the
shutoff depth.

Sincerely,

Rob James
Computational Hydraulics Int.
www.chiwater.com
Tel: 519-767-0197 x1002

On 2012-02-05, at 6:46 PM, "Nick Andrewes" <Nick.A...@GHD.COM> wrote:

> Hi there,
>
> I am after some advice on the use of pumps in EPA SWMM.
>
> I have been using EPA SWMM to model a storm water scenario that
> includes

> pumping between two open storages. Modelling has been undertaken on a
> 6

> min timestep over 3 years.
>
> I have two variable speed drive 'type 2' pumps operating based on
> start
up
> and shutoff depths at the 'source' storage as follows:
>
> Pump 1
>
> Initial status: OFF
> Startup Depth: 1
> Shutoff Depth: 1.3
>
> Depth (m) Flow (CMS)
> 0 0
> 0.999 0
> 1 0.015
> 1.2 0.015
> 1.201 0.03
> 1.3 0.03
>
> Pump 2
>
> Initial status: OFF
> Startup Depth: 1.301
> Shutoff Depth: 3
>
> Depth (m) Flow (CMS)
> 0 0
> 1.3 0
> 1.301 0.23
> 1.4 0.23
> 1.401 0.43
> 3 0.43
>
> I am concerned the pumps are not operating correctly based on a time
> series comparison of depths at the 'source' storage and pump flow rate.
>
> The pump flow time series shows that pumping generally occurs at the
> intended rates when the depth of the 'source' storage is appropriate.
> However in some cases the time series indicates no pumping occurs when
the
> depth time series indicates there should be pumping.
>
> Additionally, when there is zero flow in the pumping time series in
> some

> cases the depth of the 'source' storage appears to reduce at a rate
> similar to what would be expected if pumping was occurring. However
> in other cases where pump flow is zero and the depth is within pumping
range,
> the depth of the 'source' storage does not reduce.
>
> Pump 1 and pump 2 are reported in the 'highest flow instability indexes'

> table with values of 31 and 1 respectively. I have tried other pump
> setups including using a single pump and a force main pipe instead of
> a direct pump connection between storages but have not been able to
achieve
> a more stable setup.
>
> Neither the storages being pumped from or two are reported as having
high
> continuity errors.
>
> At this stage I am unsure if this is a reporting or modelling issue
> (or
> both) and would appreciate any feedback from people who may have
> encountered this before or could suggest anything I might try.
>
> Some additional information is included below:
>
> 1. Model numerical precision is 4 decimal places for depth and flow 2.
> Flow routing continuity error is 0.025 % 3. Pumps are directly
> connected between storages 4. A control rule is in operation for
> another pump in the model. The control rule specifies pump operation
> based on month of the year. This does not correlate to when pump 1
> and pump 2 appear to be malfunctioning

> as per the time series.
> 5. Other than pumping losses occur through monthly evaporation @ a
> peak
of
> approximately 7 mm/day.
>
> Thanks for your help.
>
> Regards
>
> Nick Andrewes
> Environmental Engineer | Waterways & Stormwater Service Group
>
> GHD Accomplish More Together
> T: 61 3 8687 8000 | V: 318626 | nick.a...@ghd.com
> 180 Lonsdale St Melbourne VIC 3000 Australia | http://www.ghd.com/
> Water | Energy & Resources | Environment | Property & Buildings |
> Transportation
>
> Please consider the environment before printing this email
>
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------------------------------

Date: Tue, 7 Feb 2012 14:49:54 +0000
From: "Gregory, Mike (Canada)" <Mike.G...@AECOM.COM>
Subject: Re: 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

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

End of SWMM-USERS Digest - 6 Feb 2012 to 7 Feb 2012 (#2012-12)
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