Stormwater Pollution Prevention

I’m glad to see “Green Infrastructure” become au courant, although, as with “Low Impact Development,” it’s one of the those squishy terms that invites expansion, and drift.

“Low Impact Development” is used to refer to everything from sensible urban planning to water conservation, and now “Green Infrastructure” shows up in conversations about everything from building with recycled materials to planting trees. It’s all good, I guess.

For a while there, I was using “Low Impact Development Drainage Design” to keep things focused on what LID means to me, which is designing land development projects to treat runoff pollutants and mimic predevelopment hydrology. Maybe I’ll need to start saying “Green Infrastructure Public Drainage Systems” to keep the focus on designing—and retrofitting—streets and storm drains.

As Green Infrastructure becomes a thing, I’m trying to contribute by developing methods to rapidly identify retrofit opportunities and carry them forward to conceptual designs. Wonderfully enough, I’ve got an assignment to do just that. On Wednesday, I gave this 15-minute presentation at City of San Jose offices.

I delivered this presentation today on “20 LID Lessons Learned” at the California Stormwater Quality Association’s (CASQA’s) quarterly meeting in Sacramento.

The trip was just about perfect: I left the house at 6:28, BART at 6:30, Amtrak from Richmond at 6:47, beautiful views of the Carquinez Strait at dawn, a brilliant red sunrise over Suisun Bay, and into Sacramento on time at 8:37. Then a lovely morning stroll through Old Town Sacramento to the Holiday Inn. A day sharing information and stories with colleagues, and then the reverse trip: 3:30 Amtrak departure, a bit of a nap, and BART delivering me home by 5:30.

I just received the final version of the Bay Area Stormwater Management Agencies Association (BASMAA) MRP 2.0 Provision C.3 White Paper, including some final edits from my coauthor Jill Bicknell.

The “White Paper” provides technical data, analysis, and rationales to support some key changes to the California Regional Water Quality Control Board’s (RWQCB’s) stormwater requirements for land development projects in the Bay Area.

At BASMAA’s monthly Board meeting yesterday, as Chair Matt Fabry accepted a motion to forward the White Paper to RWQCB staff, he thanked us for our work, and he noted how difficult the process of preparation and review had been.

I seconded that thought silently. With 76 BASMAA member agencies in the review loop, it wasn’t possible to get consensus to propose a top-to-bottom overhaul of the requirements.

Many of the current requirements (in MRP 1.0) are vague, outdated, or wrong technically. Municipal staff lament this, and they lament the time they waste figuring out how to apply this regulatory mess to real-world development project proposals.

However, by now each of the 76 agencies has developed their own interpretations and ways of doing things, and the staff of each doesn’t want to change that for regional consistency.

There’s a more broadly applicable lesson there, I’m sure.

Anyway, I’m proud of the stuff that stayed in.

Last year I completed the BASMAA Post-Construction Manual, which applicants for development project approvals will use to design site drainage and incorporate rain gardens (bioretention facilities) into their projects. The manual implements requirements in Provision E.12 of the California State Water Resources Control Board’s Phase II Small MS4 General Permit.

The manual will be used by Marin, Sonoma, Napa, and Solano Counties, and by the small cities within those counties, so it has a fairly wide reach. It can (and I think will) be adapted for use by smaller cities, towns, and counties throughout California.

During January I completed an Excel-based calculator that should facilitate the iterative design process needed to prepare an elegant and optimal LID drainage design. It felt great to create what I think will be a quite useful tool in only a day (project budget was 8 hours, prepared for the City of Napa).

Additional resources: The instructions are in a tab within the calculator, but it might be helpful to also have them as a separate Word file. Also, the manual includes Technical Criteria for Non-LID facilities, but for bewildering and complex reasons these had to be published separately.

I’m on the agenda for the quarterly meeting of the California Stormwater Quality Association (CASQA). The meeting is scheduled for March 12 in Sacramento.

The theme for the meeting is “Low Impact Development (LID): Lessons Learned” and the title I’ve been given is “Integrating LID into the Planning Process and LID Site Design.” I thought I might be up there for more time; however, I see I’m one of four speakers in a 105-minute session.

I’m thinking I’ll make the actual title “20 LID Lessons Learned in 20 Minutes,” which should make for a lively and fun time at the podium.

I’m also on an afternoon panel on “The Future and Needs for LID” in the afternoon.

It’s been a great experience being part of the Ohlone Greenway Rain Garden from first concept to completion of construction.

Today, as the rain started, I got up from my desk and walked around the corner to see it christened by its first stormwater flow.

Plug on downstream side

To get runoff from the previously existing storm drain into the rain garden, the contractors plugged the downstream pipe with concrete. We had them put a 4-inch diameter plastic pipe inside the plug, with a cap on it. As long as the cap is on, water will back up, rise in the manhole, and discharge through a connecting pipe that comes in at a higher elevation.

Runoff collecting in the plugged manhole

The connecting pipe leads to the rain garden. When I arrived, it had been raining for a while, but there was nothing flowing into the rain garden. I went back to the house to get a tool to pop the manhole cover. When I looked down, I could see some runoff had started to collect, but was still backing up, filling up the pipe on the upstream side.

I waited a while for the manhole to fill. When runoff had backed up in the upstream pipe all the way to the pipe’s crown, the manhole began to fill quickly. I replaced the manhole cover and headed over to the rain garden.

The first runoff enters the rain garden.

I only had to wait a minute or two before the runoff exited the pipe with a gurgle and a gush and flowed across the mulch.

I went back later, at dusk, to see what the rain garden looked like after receiving runoff for much of the day.

The rain garden after a day of rain.

Here’s what it looks like when it’s not raining: a great place to play.

The rain garden on a sunny day.

Seven years ago, I was involved in a long battle with the staff of the San Francisco Bay Regional Water Quality Control Board over Low Impact Development (LID).

Back then, we (Contra Costa County municipal stormwater NPDES permittees) were the LID advocates. We wanted to disperse runoff to landscaping, infiltrate runoff, and use bioretention to control the rate and duration of runoff flows from newly developed sites. Water Board staff insisted on engineered basins and, despite our entreaties, had their Board adopt technical standards written around the use of engineered basins.

So we had to prove our case that LID could meet those standards. Water Board staff made it tough, sitting on our correspondence for months without bothering to reply, and then recruiting self-interested experts to assist them in making the case against LID.

In the end, we got Water Board staff to take our LID program to their Board for approval. As part of the deal, Contra Costa permittees agreed to do some monitoring to verify the in situ performance of some bioretention facilities.

Now, finally, we’ve got two years of data–well almost two years; I hope it rains at least once more before summer. Even after all this time, there are very few published studies of bioretention performance, and perhaps none that continuously monitored the facilities through an entire season.

Contra Costa County Flood Control and Water Conservation District staff did the monitoring. Brown and Caldwell staff will take the data and compare it the performance predicted by a continuous-simulation model. Then they’ll adjust the model so the output conforms more closely to our data. They they’ll use the adjusted model to predict facility performance over very long periods (including performance during rare, large runoff events that haven’t happened in the past two years).

The kickoff meeting for the modeling part of the effort is tomorrow morning. I’m looking forward to touring the test sites with the whole team.

And that 7-year battle? The San Francisco Bay Water Board staff’s can’t-use-LID, basins-only standard is still in place. And the permit renewal, due in 2014, is coming up fast. We’ll see what we get from the results.

Here are the Powerpoint slides from my presentation to land development professionals in Corona, CA on January 28. I’ll be down there again February 13th for a repeat. Later: Here is a .pdf of the slides as well.