waterblogue

Legacy

You’re a landowner, one who may want, or need, your land to produce a material gain, for you, or maybe for your heirs. But this is not any land, this is your land, your legacy. You look around at the sort of development that is covering the land – the cookie-cutter subdivisions, the clearing, the stream pollution – and you are not impressed. You want your land to do, to be, something meaningful. You want to preserve the general character of the land, of the neighborhood, to maintain a sense of place, to deliver that legacy as much as possible while producing an acceptable gain. And you recognize that water is the key resource in all this, that to deliver material gain while not further degrading water resources, you’ll need to pursue a sustainable water model, one that maintains, perhaps even enhances, the water environment, the hydrologic integrity of the land. Is there a model you can follow that may deliver on that aim?

There is! And one well chosen project could show everyone what that looks like and how to do it. If you are “that one landowner”, who values legacy, values sustainability, who wants your land to make a statement of your values, this is for you. We should talk.

You will of course want to know how you would put this “shining example” on the ground, and why do it this way rather than using conventional water management practices. Before talking details, though, understand that the sustainable water strategies employ nothing new or exotic. I have personally planned, designed, permitted and overseen the installation of all this water infrastructure over the last 40 years. It is all feasible, it is cost competitive, and every component of it is well understood, well proven practice. The “shining example” would just integrate it all into a unified set of practices, delivering fiscal efficiency while maintaining environmental integrity.

The Elements of Sustainable Water Development

Water management strategies that can actually be hydrologically restorative, rather than degrading, were reviewed in the last post on the Waterblogue, “Can we develop our way to sustainable water?” In brief, they include:

• Each building would supply its own water. Building-scale rainwater harvesting (RWH) avoids the conventional extractive strategies. You just harvest what would otherwise be “excess” runoff created by placing impervious surfaces – rooftops in this case – on the land.
• Wastewater would irrigate the landscape. Wastewater management is focused on reusing this water resource to provide an irrigation water supply on the development.
• Stormwater would be held on the land. Stormwater is managed to hold on the developed site as much rainfall as would have infiltrated, rather than run off, the native site, so not “desertifying” the land.
• Landscaping would reflect a regionally appropriate aesthetic, centered on native plant palettes, maintaining a sense of place.

Employing these strategies can also result in reduced up front costs – and likely reduced costs overall – compared with following the conventional water management strategies used on most developments around here. So it is expected that you would save money as you save water, and do an overall much better job of protecting, if not enhancing, the water environment.

Sustainable Water Supply:  Building-Scale Rainwater Harvesting

All of our conventional water supplies are watershed-scale rainwater harvesting systems, using rivers, lakes and aquifers as the storage “cisterns”. Building-scale rainwater harvesting simply implements that very same strategy at the building scale. Basic math shows what is needed to make it sustainable. It’s every bit as reliable as any of the conventional strategies. But doesn’t degrade the water environment, rather sustains it.

Now a bit about the nature of such a development. It is presumed we are looking primarily at housing development. To make a building-scale RWH system a sustainable water supply would require a rather large roofprint area, so it may be presumed that such a development might only cater to large – so high dollar – houses. But that is not necessarily so.

See the table in Figure 1 below showing the results of running the Rainwater Harvesting Model using Austin historic rainfalls. This indicates that, to support a family of 4, you’d want a roofprint of 3,500 sq. ft. This can be readily attained over a rather modest 3-bedroom house, as is shown in Figure 2. As that drawing shows, the water storage cistern can be designed into the house footprint, so not encumbering the area around each house with a free-standing cistern. You can see here that this water supply strategy could readily serve houses that could be “affordable”, if that’s the desired market. This strategy can serve such modest homes or high-end estates; it scales to either.

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In regard to cost, while of course the building-scale RWH facilities will add costs to each building, this strategy avoids costs for drilling wells or extending piped water to the development, and the costs of a distribution system within the development. There is also a “time value of money” savings, because while the conventional supply schemes would entail expenditures for permitting and for wells and pipelines well before the first building could be started, under the RWH strategy the water supply system for each building would incur no costs until that building is built. Likewise, this timing also minimizes the amount of money put “at risk”, since again there would be no up front money required; it is all expended as part and parcel of creating the revenue-producing components of the development, the buildings.

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As for the practicality of using RWH for water supply, the feasibility, workability and effectiveness of this strategy is demonstrated by the presence of thousands of houses using this strategy in Hays County alone. Indeed the Texas Region L 2026 Regional Water Plan stated there could be over 200,000 RWH systems in Hays County by 2080. So it is not at all a stretch to envision RWH as the water supply strategy over a whole development; this would just be catching a wave that is already swelling.

Note also the very circumstance that a large portion of the annual rainfall would be harvested and stored in the cistern, rather than running directly off the roofs. This imparts a hydrologic improvement over the conditions in a conventional development. You’re making that patch of ground, now covered by a building, perform hydrologically more like that patch in its native state. “Absorbing” the smaller rainfalls, producing runoff only from large storms or prolonged rainy periods. So besides avoiding the extraction and degradation of local water supplies, the RWH water supply strategy imparts a hydrologic improvement over conventional development, just as a matter of course.

Smart Wastewater Reuse and the OSSF Advantage

Wastewater management is centered on reusing this water resource to provide an irrigation water supply. With roof-harvested rainwater being dedicated to interior water usage, this reuse will allow for considerable irrigated landscaping without drawing on local groundwater or needing to expand roofprints to produce greater RWH supply. That’s the water resources reasoning for this strategy.

There are also cost reasons. Based on my 40 years of experience in this field, wastewater management in the hinterlands would be executed in the most cost efficient manner, while also best blunting environmental liabilities, by utilizing highly distributed systems, treating and reusing the wastewater close to where it is generated, so eliminating most of the collection system. Which in a conventional wastewater system composes 70-80% of total system cost. So big savings, simply by decentralizing.

But of course you’ve got to decentralize in an environmentally sound manner. The distributed systems employ “fail-safe” treatment units producing high quality effluent, and disperse that effluent in subsurface drip irrigation fields. The plants being irrigated would evapotranspirate most of that water, but what does percolate – some would over parts of the winter and during rainy periods any time of the year – that water would be well treated before it could join environmental waters, first by the treatment unit and then by percolation through the soil. So, quite environmentally sound.

Those distributed treatment units can be built quickly, reducing up front cost and time lag until the systems can come on line. Saving money. Drip irrigation maximizes irrigation efficiency while sequestering the water underground, so that grounds beautification up around the buildings – the landscaping likely to need irrigation – could be irrigated without hazard of contact with the effluent. So safely substituting reclaimed water for potable water, saving money.

This “decentralized concept” strategy was explained more fully on the Waterblogue in “This is how we do it”, showing how this concept might be arrayed to serve houses on separate fee simple lots. Figure 3 shows how that scheme could be applied in a neighborhood of a Hill Country development. In that case, the wastewater system would have to be permitted at TCEQ under their “municipal” permitting program. The rules in Texas do not allow systems to be permitted under the on-site wastewater system rules – OSSFs in regulatory speak, standing for On-Site Sewage Facilities – if the buildings to be served lie on separate legal tracts. Even under this TCEQ permitting though, as reviewed in “This is how we do it”, it is expected that this sort of system would be more fiscally efficient, more societally responsible, and more environmentally benign than systems done in accord with conventional practice.

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If, however, a condominium ownership regime is deemed marketable, collective systems serving multiple buildings could be permitted under the OSSF rules. Same high quality systems, just a different permitting process. One that would significantly shorten the time line for approval and permitting – nominally 30 days, vs. a year or more under TCEQ permitting – and would avoid any delays due to protests of the permit, as OSSF permits are not subject to that. As time is money, shortening this timeline would save you money right there.

That same high quality system could be applied house by house, if your market were houses on larger fee simple lots. This sort of OSSF – high quality pretreatment and subsurface drip irrigation dispersal – has been permitted in Texas for 3 decades. An individual OSSF for each house, though the treatment unit is more costly per house than in a collective system, of course eliminates all collection system costs.

In any case, a collective distributed system – that would allow the houses to be clustered, so leaving more open space – would minimize money put in the ground just to move the stuff around, lowering total system cost. Most of the investment is focused on the real job to be done, providing high-quality treatment and beneficial reuse to impart environmentally sound management of this water resource.

Then too, an OSSF could be permitted and installed while the houses are being built. Again, the “time value of money”. And minimizing the money put at risk, not having to be expended well up front of the revenue-producing components of the development coming on line.

While the amount of water that would be obtained via wastewater reuse may be insufficient to keep a conventional landscape looking lush through the summer, a regionally appropriate landscape aesthetic could be quite well maintained on that supply. An example of a front yard landscaped with native plants is shown in Figure 4. Irrigating this landscape as part and parcel of the wastewater management system, rather than having to create a separate irrigation system, saves money.

Employing that regionally appropriate landscaping aesthetic can help maintain a sense of place on the developed property. This would be the “face” of the development, a visual statement of sustainable water bona fides, adding intrinsic value to the clear functional role.

Stormwater Management as Land Restoration

While using RWH for water supply and a distributed, reuse-focused wastewater management strategy would “merely” blunt the extraction and degradation of water resources, it is in the arena of stormwater management that a development could really shine, actually imparting some hydrologic restoration of the site. Especially given that much of the land in this region has been degraded by past land use practices, such as historic over-grazing. So even a modicum of measures that would hold water on the land that would otherwise drain away might actually improve the site hydrology, somewhat restoring it to “native” condition even with some development being placed on the land.

The degree to which this might be attained would, of course, depend somewhat on the intensity of the development. In the sort of low-to-moderate density hinterlands development for which this water management scheme would be most applicable, it is expected that total impervious cover would be “low”. For example, in the proposed Hays County rules to govern “conservation development” – of which this “shining example” project could be an exponent – total impervious cover on the project would be limited to 20%. But even a typical exurban residential development would have a gross impervious cover level below 30%.

So there would be a lot of area available in a “shining example” development to house the stormwater retention facilities that would hold water on the land, and thus somewhat hydrologically restore previously degraded land, even as it is developed. The proof that these works could indeed restore the land is found in the work of Drought Proof Texas and Symbiosis, folks making a living doing this work for landowners, reflecting its value. A somewhat spectacular example of hydrologic restoration is Selah, the Bamberger Ranch, on which springs were restored! All this is accomplished with the sorts of landform alterations and plant choices to capture and insoak rainfall that would form the stormwater management strategy in a “shining example” project. Landform alterations, like rain gardens and bioswales, which themselves would be a part of the regionally appropriate landscaping aesthetic … that would not require irrigation.

Let’s Talk About Where to Go Next

This somewhat cursory overview of what would compose the “shining example” project needs of course to be further detailed, but the devil will always be in the details. So to get more specific, we really need to focus it on a specific piece of land. And on the landowner’s vision. If you are contemplating developing your land, and this more fiscally reasonable, more societally responsible, more environmentally benign way of development caters to your sensibilities, how about we talk? No obligations, just a conversation about how we create a “shining example”, how we may indeed develop our way toward sustainable water.