How much of a good thing – in this case beer – is a bad thing for the wastewater treatment plant operated by the Warwick Sewer Authority?

That may seem like a pretty obscure question unless you’re one of two breweries operating in Warwick, or you read the sewer authority’s notice of a public hearing for Thursday, April 25 at 5 p.m. at authority offices, 125 Arthur W. Devine Boulevard. The purpose of the hearing is to consider modifications in the “carbonaceous biochemical oxygen demand [CBOD] local limit for breweries MAICS Code 312120 inclusion of definition for maximum allowable industrial loading.”

Got that?

For Betty Anne Rogers, industrial pre-treatment director at the Warwick Sewer Authority, the proposed modifications are a matter of ensuring operation of the wastewater treatment plant while enabling the growth of new industry and especially breweries in the city. As Rogers acknowledges, the “bugs ” or bacteria that clean the wastewater require nutrients and the residuals of brewing resulting from the cleaning and sanitizing of tanks are good food for the bugs.

It’s a matter of moderation, however.

“We welcome it,” Rogers said of effluent from the brewing process, “but we don’t want a slug of it.”

That happened when Supreme Dairy and Rhode Island Beverage were operating in the late 1990s and early 2000s and plant operators saw a spike in CBOD.

Too much beer is not good for the bugs. In fact, says Joseph Haberek, supervising sanitation engineer at the Department of Environmental Management, it will kill them. If that were to happen, the high level of nutrients would be discharged into the Pawtuxet River and that would deplete oxygen, killing life in the river.

So, how much is too much?

Additionally, and here’s the balancing, at what point do measures become punitive, if not too costly, that they make the city unfriendly to industrial development and brewing?

The city’s two breweries are already chaffing under regulations that, in the case of Proclamation on Jefferson Boulevard, has had them invest more than $100,000 in pre-treatment equipment, a measure that brewery co-owner Josh Karten described as frustrating and which he felt turned them into a “guinea pig” for figuring out how to manage brewery waste in the city. At the much smaller Apponaug Brewing at Pontiac Mills, co-owner Tamara McKenney said she would have opened in Cranston had she known what she would be faced with in terms of testing and burdensome regulations.

“What makes that side of the wall different than this?” she asks, pointing to the stainless steel brewing tanks and then, on the other side of the wall, the bar where customers are gathered. Beer from the brewing process is discharged into the sewer system, but so, too, is beer from cleaning the glasses of customers. McKenney points out that restaurants and bars across the city aren’t faced with the regulations she faces.

McKenney estimates it will cost her operation $5,000 a year in licensing and testing fees for the brewery and restaurant. On top of that, she is faced with water – “we use a lot of water” – and sewer usage fees and surcharges estimated at $10,000.

The sewer authority is listening. The proposed modifications would increase the levels of CBOD the breweries could discharge daily to the system.

Haberek explains that after an analysis of the Warwick plant and after subtracting the CBOD from residential users, a discharge of 10,200 pounds per day was set aside for industrial use. DEM and the authority then calculated of that total 4,593 pounds had been “assigned,” leaving a reserve of 5,289 pounds.

“We’ve got plenty of capacity and will still be under the maximum,” said Haberek.

Of the reserve, 800 pounds per day would be set aside for Proclamation and 300 pounds for Apponaug.

There’s more to it than daily limits.

Rogers is concerned by the given concentration and volume of flow, that “slug” as she calls it. She said under current industrial regulations, users are permitted to discharge 2,500 milligrams of CBOD per liter. Rogers said the raw discharge from Proclamation measured at 70,000 milligrams per liter and after pre-treatment was reduced to 18,000 milligrams.

“We have to be very protective of our facility,” said Rogers.

Yet, she said, the authority wants to see commerce grow and she was aware Proclamation would not be capable to meeting the 2,500 limit, “so, we gave them [breweries] a mass-based limit.” In addition, Proclamation has a maximum flow rate of 500 gallons an hour.

Rogers is not as concerned by Apponaug, as it is a smaller operation.

The breweries are taking measures to pre-treat waste. Both Proclamation and Apponaug remove solids from the waste stream. McKenney said she has been in contact with local farmers concerning the disposal of mash from the brewing process, an idea that Karten, too, has expressed keen interest in.

If she had to do it over again, McKenney said she would have opened elsewhere and in a larger facility. She has found the response to Apponaug positive and she can see the business growing, but in terms of brewing more beer, “It’s impossible to get any bigger.”