Natural Pool Conversion – Meeting with Paul Kephart

Wood rat and I decided that if we are going to go forward with the natural pool conversion, we need some inputs from a professional with experience in the field. On Friday July 29 we had the great pleasure of spending a couple of hours in discussions with Paul Kephart of Rana Creek about how we might go about it.

Talk about experience in the field – take a look at the Rana Creek project page. Especially the Transbay Transit Center project.

Paul also mentioned that Rana Creek has done two other somewhat similar projects for private residences.

I’m happy that Paul is happy to provide support services, with Wood Rat and me doing all or most of the actual installation work ourselves. Rana Creek would provide the technical analysis and engineering/design specs to guide us towards success.

On seeing the pool area, Paul immediately visualized some great ideas. His approach is to add the regeneration zone as a separate water feature and not disturb the pool itself at all. Here is the brainstorming sketch that emerged by the end of the meeting. (It overlays a fuzzy but useful blow-up of a Google earth printout, for a quick-and-dirty site map):

Like any brainstorming sketch, it’s a palimpsest (ooh - one of my favorite obscure words) of various ideas – for example, the areas marked off inside the pool were part of a discussion about subdividing the existing pool area into a swimming and a regeneration zone. Paul voiced my own thought that this could prove challenging to engineer – and a separation of the areas also addresses Wood Rat’s thought that it is better not to “swim with the snakes!” Not that there would be snakes. But there certainly could be red legged and yellow legged frogs as well as the little tree frogs.

The upper left of the drawing shows how we’d add a raised area, where water is pumped to the top at the back, and meanders down to the pool through different planting cells. Perhaps a rocky area at the back, with ferns and other yummy wetland plants, followed by (probably) three successive planting cells for the wetland / riparian plants (and their friendly bacterial associates) that will do the filtering. Specific sizing and other details would require proper analysis; this was just a brainstorming session.

We might also use the existing hot tub, which contains a return drain to the pump, for deeper water wetland plants (and buy a more efficient hot tub sometime down the road).

We would cut a keystone (wedge) shape out of the big concrete slab behind the pool to accommodate this raised feature - and reuse the removed concrete, naturellement.

Closer to the pool, the water would pass under a wooden bridge, pretty much level with the surrounding concrete surface, before tumbling either into another plant cell or directly through a notch and into the pool over a very low wall. The sketch of this doesn’t show the elevation, just the concepts of the pools and the bridge. The amount of elevation required would again depend on analysis.

The overall look could be curvy and naturalistic or straight. We favored straight, for a modernist type look that’s simple and is in keeping with the look of the pool. Also easier to build. The plants will provide all the naturalism I need. I think of the spring boxes on the Spring trail in Pogonip, a local county park – very simple.

(From the blog “Following Fragraria (pt. 2)”)

There would be planting opportunities outside of the deeper water pools too, I think. Maybe room for some Leopard Lily - the ones I blogged about recently are smack in the middle of a seep area near the creek!

As Paul thumbed through the Michael Littlewood book, Natural Swimming Pools, Inspiration for Harmony with Nature, he said that it is an excellent resource, a bible for that “all-in-one” lake recreation approach. However, he considers that method somewhat “first generation.”

Here’s a nice example of how that swimming pond approach might look:

(From an interesting blog post, Natural, nontoxic swimming pools.)

In the more engineered approach Paul favors, the water moves a bit more briskly, which can have some benefits, for example, in deterring algae (and mosquitoes presumably). It is also much more suited to pool conversions, of course. I forget now the additional arguments he made – I’ll listen to the recording and fill in some gaps later on. (How nice of him not to mind me recording the meeting – and blogging about it - I know there will be details I’ve forgotten.)

We talked a bit about algae blooms and other maintenance / disaster scenarios. Paul said that algae blooms occur more where there is a lot of variation in seasonal temperatures, unlike the Central Coast area of California. And if we added solar water heating we could probably ensure an even more even temperature of around 73 degrees.

The entire feature would probably be built out of concrete, a material Wood Rat is used to working with, with maybe some additional rocks.

When Town Mouse called to ask about the visit, she was excited and enthusiastic. But I immediately remembered everything she’s said and written about concrete as a non-renewable material! So that’s something to ask / think about. But I’m not sure how such a feature can be done with other materials, or done so conveniently and by us. But as she later said, sometimes concrete's just the right thing.

As far as maintenance, Paul said we’d have to cut back the plants every few years – we didn’t talk so much about maintenance - for me it’s a garden area to be maintained, and not a boring chore -- and I’ll learn it all with pleasure. We have a lot of questions - the existing pool still needs to be cleaned and vacuumed, right? What about water chemistry, do you still have to monitor that but in a different way? Etc etc...

As regards the plants to use – this is terrifically exciting – actually I didn’t sleep well that night for thinking about it all: Paul is confident that we can use nothing but our local indigenous wetland species. He noted some on the way up to our place, along the nearby creek side road.

Paul was as enthusiastic as I about using and propagating local natives, and Rana Creek will work up a plant list based on that requirement. Yay! He was also enthusiastic about my “Grows Right Here” nursery idea and domain name, and pointed out that the regeneration zone could also be my propagation area for the local wetland and riparian species.

It’s possible we might also add some ornamental additions – a few non-invasive and non-hybridizing-with-the-locals type plants that might add pizzazz -- Pete Veilleux of East Bay Wilds is already giving me suggestions!

We brainstormed some other fun ideas in the course of the visit - maybe a miniature redwood forest zone. Elfin redwood forests occur naturally in some maritime chaparral stands in Monterey County, where salt spray kills growing leaf tips. (Coast Redwoods: a Natural and Cultural History p 44).

Another suggestion from Paul - we could cut holes in the existing concrete, for planting shade trees. Providing some shade will be necessary for some of the riparian plants such as ferns. I wonder if we can use our local Ceanothus thyrsiflorus there? I've got some nice ones in five gallon pots, grown from local seed.

As regards the infrastructure for the feature, Paul surprised me by saying that we can use our existing pool pump. I thought we’d need a different kind, slower – but that’s from reading about the pond recreation approach, which does use slower water movement. So we would just reroute the outflow of the pump via a pipe behind the fence of the pool area to the top of the regeneration zone (instead of to the DE filter). We can calibrate the flow using the existing splitter that directs the water either to the pool or to the hot tub or to both.

Paul is all about sustainability and fully using the natural resources of a place, especially the sunshine and the water that falls thereon. We could use solar water heating, for example, and also solar panels for running the pool pump. We could harvest rainwater into a 5,000 gallon tank (placement TBD) and catch water from the roof. It would integrate into the swimming pool system – taking excess water as necessary and providing water when levels get low, as well as providing irrigation water and so forth.

These are later phase ideas – it’s good to have a sense of all the possibilities.

The next step is for Paul to come up with a more formal proposal. I’ll keep you informed.

Next day, I took a walk down that creek-side road to get a closer look at what’s growing there. If you want a sneak peak at an upcoming post, you can view a gallery of these local wetland plants here - and maybe help me ID them!

Are we excited? Oh yeah, just a little bit!


This looks reaallly interesting. I've read a lot about these being all the rage in Europe. Do keep us posted.
Gail said…
Very interesting and the link led to more interesting info/photos. gail
Town Mouse said…
What an exciting prospect! And so many opportunities to learn...