I Forgot That It Runs About 20 Times Faster If You Turn Off the Treatment Plant Averaging

Notes on changes to MACRO model input file (*.cmm) Eric Loucks, CDM

Here's some MMSD basics:

There are three ways to fight overflows: 1. Increase treatment Capacity (increased blending is a form of this) 2. Increase Storage Capacity 3. Somehow manage the treatment and storage to reduce overflows

There is the added issue where the penalty is much greater for an SSO than a CSO. MMSD currently gets fined for each SSO but can have up to 6 CSO's per year without causing a violation. A lot of the operational inputs are directed at this issue. As VRSSI is increased, SSO's are reduced at the risk of increasing CSO's. The system operators choose a VRSSI value during each storm based on it's perceived severity.

The file VRSSIHINDCAST.INP contains perfect hindcasts of the best value to use in each historical storm. Perhaps a poorer set of values should be used, because these are difficult to improve upon. The minimum VRSSI (on line 14) will have some effect though. Perhaps students could use a "dummy" VRSSI file (provided). Then VRSSI is controlled only by the minimum value on line 14. You can vary it from 0 to the total volume of the tunnel. MMSD has slowly increased it over the years from 40 MG to the current 250MG. (5347594 to 33422460 cu ft).

Here's a summary of everything else you can change in the CMM file, and some thoughts:

Make the tunnel bigger on line 13. It's currently 405 million gallons which should be 54,144,385 cubic ft. Expanding it costs about $2/gallon.

The maximum pumpout rates on lines 20 and 22. Right now, it takes 3 or 4 days to empty the tunnel. More pumping capacity might be beneficial, especially if you make the tunnel bigger. A 45 cfs pump costs $5 million.

Lines 23-29 shouldn't be changed.

Lines 30-32 are physical limitations of the system too, but interesting things might happen if you could divert more flow to SSWWTP. Diverting less is a zero-cost option but this will increase CSO's.

Lines 33 and 34 are another quirk. Inflow to JIWWTP is through two siphons and these are the capacities. Amazingly, the treatment capacity (511 or 603 cfs) is larger than the total siphon capacity (473 cfs). Each siphon will cost $12 million to upgrade to 400 cfs.

Blending is limited by permit to 94 cfs, but perhaps we can get DNR to allow us to double it. If you do, you'll need to increase the chlorination limit too or there won't be any benefit.

If you want to increase the treatment plant capacity at JI, you'll need to do it on both lines 36 and 38. It costs about $1 million per cfs. South Shore is increased only on line 40.

I suggest turning treatment plant averaging off (line 10 set to "1"). Then only the first values on 38 and and 40 are used and lines 11, 39 and 41 are also irrelevant. It runs about 20 times faster if you turn off the treatment plant averaging. There is a lot of overhead tracking the average inflows over the past 24, 48, 72, 96, 120, ..... and 720 hours.