Document Kz6rqV32g51K8op5m6RwYE0nw

AR226-2324 Charles J Zarzecki 04/03/2003 01:34 PM To: cc: Subject: Catherine A Barton/AE/DuPont Re: Beychok Article 0 ) Cathie, l think they are really not 2separate issues. Part of the work Is to look at future tratment Issues, and part of the work is to develop the required Input parameters for c8 for the T O XC H EM model, which will be used to estimate c8 em issions from the wastewater treatment tanks. W e will then use these emission rates in our air dispersion modeling. At least that is my understanding of what's going on. W hy would they need 2 air people (P J and I) to be included in the partitioning activities? Charlie Z. Catherine A Barton $ Catherine A Barton ' 04/03/2003 09:38 AM To: Charles J Zarzecki/AE/DuPont@DuPont cc: Subject: Re: Beychok Article 0 Yes, I meant the 14th...thanks for straightening me out. 1drew the same conclusion you did, that the partitioning work was going to delay our getting an emission rate number quickly. But, at the steering team meeting yesterday, Maria Angelo said the partitioning work will not hold up our modeling work; they are 2 separate Issues. The partitioning work is being performed to look at future treatment opportunities. The modeling work we discussed at our meeting a week or so ago was to simulate current conditions. She told me different people were in charge of these 2 modeling efforts....! hope she's right. Anyway, what you're telling me is that we can have the model results in 2 to 3 weeks after we get the emission data from the site. That seems reasonable to me. Thanks, Cathie Charles J Zarzecki Charles J Zarzecki " 04/03/2003 09:31 AM To: Catherine A Barton/AE/DuPont cc: Subject: Re: Beychok Article 0 Cathie, EXD747743 First, by "Monday's meeting", I assume you mean April 14? Regarding CW , base on my schedule and yours, I would say a minimum of 2 weeks. However, I was at the C W wastewater partitioning team meeting yesterday, and it looks like they will only have a sampling plan proposed by Monday. Then they will have to implement it, get the results, and then we can move ahead with the T O X C H E M modeling. After that, we will have an emission rate for the wastewater. Looks like it will be awhile before we can do any ambient air dispersion modeling to get definitive results, anyway. A s a first cut, I guess we can run the stack numbers to see what they look like. Chariie Z. - Catherine A Barton ^ Catherine A Barton 04/02/2003 04:57 PM To: Charles J Zarzecki/AE/DuPont@DuPont cc: Subject Re: Beychok Article Q Chariie, First, thanks for taking the time to go over Beychok's article thoroughly. I have the same instinctive feeling that you do: to lambast (yes, its' a great word) the model is a losing battle. W e have to develop a more positive strategy that the agency can live with. I like your alternative strategy of fine-tuning our inputs. I want to contact the site guys who did the estimates to see how much better they think they can get (I'll do that tomorrow). For Monday's meeting, I want to put together a graphic that shows them some options. Let me soak on it overnight and run something by you manana. Incidentally, I met with the Cworks strategy team and they are happy with our modeling plan. Ann Masse wants me to get the em issions information from the site guys by 4/11 so we can start cranking numbers. Help me with this: w hen d o y o u th in k we can re a llistica lly have the firs t round o f a m bie nt a ir n um b e rs? I have to convert my flow diagram into text for Ann, and she wants me to put in real dates for deliverables (pending her boys get us the emissions data by 4/11). I'll be in the office tomorrow, but I think you're at home. No matter...we'll connect. thanks again, C Charles J Zarzecki / f ' Charles J Zarzecki 04/02/2003 03:14 PM To: Catherine A Barton/AE/DuPont cc: Subject: Beychok Article Cathie, EID747744 I finally was able to review the Beycbok article on error propagation In dispersion modeling. This could add fuel to Dave Rurak's fire. It's common knowledge that Gaussian models overpredict by a factor of 2, however, due to error propagation, he says as high a s 80X. Also, a s far a s 1-hour concentrations re concerned, the actual averaging time for Pasqulll's dispersion coefficients range from 3 minutes to 30 minutes, depending who you talk to. I always thought they were 15-minute averages. This short-term to 1-hour assumption can be shown (by Beychok) to result In a 2.5X ovrprediction. However, in my opinion, since the 1-hour period Is the basic time-step in the ISC (and other) model, an annual average concentration at any given receptor is 8 ,7 6 0 1-hour concentrations divided by 8,760 hours. If K predicts poorly for each 1-hour period, then it predicts poorly for the whole year. D ave has to understand that the model is a screening tool. The more accurate information you put into a model, the greater the accuracy of the prediction. Instead o f lambasting (is that a real word?) the model's 1-hour prediction, we should investigate how to fine-tune the input data and model options' (e.g. particle settling, hours of operation, hourly emission rates, more accurate model (AERMOD), etc...). Or, go out and do some sampling to get the "real thing". W hat do you think? Beychok references about a half-dozen other publications that discuss the shortcomings of Gaussian models. Some of them go way back. A s you can see, nobody really took them seriously. What I am getting at: the regulatory agencies (O EPA, W VD EQ ) are not going to want to hear about how bad ISC is for particular time periods. They may be open to other "accepted" models and to sharpening our pencils. Regards, Charlie Z. , EID747745