1 Hello. My name is John Milne, and I work as a Design Engineer - PDF document

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Hello. My name is John Milne, and I work as a Design Engineer with Clark County. I’m going to talk to you today about using “entropy-based resource management” as an organizing principle for developing sustainability strategies. 2

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This complaint was heard a lot from the environmental community when the county was developing the Salmon Creek Watershed Plan. Probably most stormwater engineers would actually agree with it. But as engineers we have to be able to elucidate beyond this observation if we are going to be able to make things happen. We need to quantify everything and convince decision-makers and a skeptical public before we can get on-the-ground results. So here we are looking further into what “mimicking a natural process” might mean in physical terms. 4

A quick reminder before we move forward. Entropy is basically a measure of the degree of disorder in an element or compound. For example, steam is a highly disordered, high-entropy form of water whereas ice is a highly ordered, low-entropy form of water. The premise here is that natural processes always act to minimize energy loss at all times and leave all resources in a state of minimum entropy after each process has been completed. By doing that, the resource is always maintained in its highest, most ordered state, at the highest energy level possible. In nature, nothing is ever wasted. Entropy-based watershed management is basically about finding simple, effective ways to maintain or create order, that is to “ create negative entropy” , in all our resource management activities. This was the holistic, watershed-based principle that the county came up with and have developed several strategies from over the years. 5

So, this strategy basically tries to manage natural resources so that each resource is maintained in its state of least entropy, its “highest” and most ordered thermodynamic state, after each and every process has taken place. If this premise is correct, you would expect to see examples of this everywhere in nature. Are there? Snowpack is one. Snowpack is water in solid phase at the highest potential energy possible. And we know that a good snowpack means a good year for the watershed environment and everything in it. But creating snowpack is a difficult, expensive task for a watershed manager. So what might the next best thing be? High Groundwater is water in liquid phase with high potential energy, and is also very useful to have. When applying this organizing principle to watershed management, it can be simplified to “pump up the groundwater as high as possible then plant everything”. So, keep groundwater elevations high (improves wetlands and supplements stream base flows) and maximize the photosynthesis going on. Or, put in sustainability terms, store as much water and energy as each watershed can handle. The ocean is not hurting for water – keep yours in your watershed a bit longer. Not being a fan of big, technical words, the phrase at the bottom of the page is the simple 6

What this organizing principle does is help us bring individual sustainability initiatives together to develop holistic sustainability strategies. We do that by “creating negative entropy”,by imposing order, at the molecular scale and also in all our other management, planning and regulatory operations. Entropy-based resource management answered the citizens request that the county move away from constructing highly engineered stormwater facilities and instead develop strategies that mimic natural processes Using it in the form of a simple “organizing principle” met my own preference for getting watershed rehabilitation projects in the ground quicker and with less fuss.

A brief side-trip to explain a bit about an important entropy-based watershed management strategy, “top-down watershed management”, and its spin-off benefits. This slide shows a natural example. Most whisky aficionados will tell you It is the water in each whisky that gives it its individual flavor more than any particular part of the distilling process. Why is single malt Scotch usually called Glen-this or Glen-that? The reason is that the water in the stream in every glen is different, due to the chemical and biological activities that take place over its journey from the mountain ridge line down to the distillery. The east highland area, including the River Spey, is very lush, and The Macallan is a nice smooth whisky. The island landscape on Islay is much harsher, and “Leapfrog” is much more peaty flavored and has more bite to it. People greatly enjoy both of them. So it seems like the glens know better than we do how to make a wide variety of good whiskies, using top-down watershed management. And maybe know best how to support a variety of anadromous salmon species also. So we can see here that utilizing natural processes can be very effective in preserving all the attributes of a stream. The stream’s “signature” is preserved, not just what we might think are its “beneficial uses”. So, to get good outcomes, we should try to use those natural processes as much as possible, by using top-down watershed management. After that, mimicking how natural processes work in our management and engineering work would also be a good idea.

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Hydrologic Accounting is a simple “apples-to-apples” quantitative method for comparing two project alternatives. It uses a continuous hydrology model to compare any two stormwater mitigation alternatives based on the computed size of the hypothetical upstream watershed that they “can provide full mitigation for”. The stormwater mitigation can be in terms of flow control and/or water quality treatment. It was used extensively in the county’s fast-paced 2008-2011 Stormwater Capital Improvement Program to determine the effectiveness of projects, select and prioritize projects, and evaluate alternative designs so that we could quickly move projects forward into construction. The 2008-2011 SCIP was by far the county’s most successful watershed rehabilitation effort. A big reason for that was that decision-makers were highly motivated to get on-the-ground results fast, and so were willing to expend funds based on reasonable assessments of the relative effectiveness of competing projects. Which is all that anyone should really need to make a good decision that is assuredly in the public’s interest. 10

This slide shows our system of graphically assessing project benefits; one use of the hydrologic accounting process. The green shading depicts the flow control benefit provided for this sub-basin by the construction of a new detention pond. The greener the basin is, the more “fully-mitigated” the catchment will be, and the better the project or plan alternative When shown in an Existing Condition GIS map of the entire county, the greener a basin is, the less a remedial project would be needed, and the lower priority any projects in that basin would have in the SCIP. Here, after building the project, the basin is around 60-80% mitigated, so any further SCIP flow control improvements would be a low priority. 11

This next example is a sub-basin retrofit plan, a much quicker way to identify and restore degraded basins than a watershed plan. The basic steps involved are........... 12

Step 2 in the Sub-basin retrofit plan process uses Infiltration Zone mapping, basically a single map mix of soil types and groundwater elevations, together with a BMP cost- effectiveness matrix to pick the most cost-effective infiltration-based BMP at every potential retrofit location. 13

To develop this maximum improvement alternative, Plan Alternative 1, we use a top down watershed management strategy, i.e. working from the ridge lines downstream, to site the most cost-effective infiltration BMPs in every possible retrofit location. Consider this graphic for a moment. It shows the maximum flow control improvement that can be made in this sub-basin, regardless of cost. A very useful piece of information for a watershed restoration program. The graphic shows a portion of the Plan. It includes a large rain garden, roadside rain gardens with overflows to a wetland/retention area, parking lot runoff interception rain gardens, “Eco-roofs”, downspout rain barrel/planter boxes, a headwaters restoration area, an existing detention pond with modified outlet controls, and reforestation areas. I’ll note here that the headwaters restoration project diverts storm flows that currently drain directly to a detention facility back to the natural flow path, so reinstating the natural hydrology that was disturbed by the amphitheater grading and street layout. Using an entropy-based resource management strategy presses you to do this; current regulations and design practices would not. Entropy-based resource management strategies develop more effective solutions, and more cost-effective projects, but they also press you to construct additional projects that current programs and design criteria might not identify, require or prioritize. 14