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This is going to be long (quasi-Vernonish), but bear with me. If you have any interests in the following, please keep reading:
- recreational water use
- politics of locally sustainable economies
- civic projects
In the recent decade, it has become very popular
around these parts (Central Plains region of the US) to attempt remediation of ecologically damaged lakes and streams. The causes of this damage are rarely discussed, but probably the largest factor is modern agricultural practices. The effects include diminished water clarity and quality, reduced diversity of plants and animals, increased population of undesirable species (carp, weeds, mosses), with concomitant decreases in recreational use and property values, and further consequences on local economies due to diminished recreation-driven income.
These remediation efforts largely consist of dredging to remove years of accumulated detritus (agricultural run-off) followed by intensive fish and plant stocking. The aim is to increase depth, improve clarity, and begin natural processes to restore chemical and nutrient levels to near normal conditions.
Remediation of this sort gets very expensive. For a small lake (under 500 acres) costs will run around 3 to 4 million dollars (US). This money usually comes from local fundraising (lake homeowners associations), some civic coffers (justified by anticipation of increased tax revenue with higher property values and return of recreation spending), and matching funds from state and/or federal programs.
So what's wrong with this?
(a). The money is a "sunk cost" - nothing is actually purchased, it pays for services rather than goods, and it is spent on the hope of future returns which may never come.
(b). It is a one-shot effort. There is no long-term management plan. The causes of degradation are never addressed. So it is likely that in 5, 10, or 15 years the water will return to its degraded condition.
So here's my proposal:
1. Use some money - say $50 - $100,000, for hydrological and ecological studies so a complete picture of the specific lake in question can be formed.
2. Select a site on the edge of the lake for locating the filtering facility. About 90 acres should do.
3. Buy a couple of suitable, large pump systems (quantity depending upon need).
4. From the hydrological survey, determine ideal locations in the lake for permanent installation of pump intake sites. These should be chosen so that the flow of water from the filtering plant back through the lake will create natural bottom-scouring currents as the water flows back to the intake sites.
5. At the filtration plant, the pump effluent (lake bottom sludge and water) will flow over a slanted slab of concrete on which moss is cultured over a sand substrate. The moss and sand will filter the water as it flows through. Filtered water flows off the slab back to the lake. Depending upon the size of the project, several different filter slabs will be made. A minimum of 2 is required: 1 for active filtering, while the other one is growing the moss culture.
6. The moss/sand culture will absorb not only the silt, but also some of the free nutrient in the lake water (ag runoff creates overnutrification of the water).
7. When the moss/sand has reached the limit of its service life, the eflluent is directed to the next filter slab (which has a freshly cultured moss/sand bed). After a couple of days for open-air drying, the moss/sand/silt/nutrient mix is scraped off the slab. The slab is then prepped for a new culture.
8. The moss/sand/silt/nutrient mix is exactly what potting soil is. So the filtering plant will also have equipment for taking this wonderfully rich soil and packing it in 10 or 25 lb bags. It can also be sold in bulk. This is the source of revenue for the plant's continued operations.
That's it in a nutshell. Here's a summary of advantages of this method over the one-shot expensive approach:
- economically self-sustaining
- on-going, long term management for continuous improvement, rather than one-shot approach
- injection of money into the local economy through employment and service fees
And for you anal types, here's an order-of-magnitude picture of the figures involved:
- Cost of traditional reclamation: $3-4 million USD for 500-acre lake
Ecological and hydrological assay: $100,000
Concrete slabs: $20,000
Pumps: $250,000 (2@125,00 ea.)
Piping, valves, etc: $250,000
Bagging machine: $200,000
Misc. equipment (bobcat, etc.): $300,000
Facility (a building): $100,000
That's about 1.25 million startup costs. Which would leave 1.75 mil for operations until profitable:
Miscellaneous (chemical testing, etc): $3,000
So that 3 million would cover all startup costs, plus 8 years of operating expenses.
Oh, one last thing: Potting soil is about $0.30 /lb. wholesale ("cheap as dirt") [granted, prices will vary greatly in different areas]. Operating expenses would be covered by selling only 600 lbs per day.
qb please meet alan and charlie and walshie
I think you would like this trio [po, Jan 03 2002, last modified Oct 06 2004]
Morro Bays problems
Mix of laymans and water treatment terminology [thumbwax, Jan 03 2002, last modified Oct 06 2004]
Siphons - Pretty
The canal which runs adjacent to the lake is for agricultural purposes - occasionally one sees fishermen - bleah [thumbwax, Jan 03 2002, last modified Oct 06 2004]
South Dakota Lakes and Streams Association
The local experts. [quarterbaker, Jan 03 2002, last modified Oct 05 2004]
Pretentious name, but clean water. [hello_c, Jan 04 2002, last modified Oct 06 2004]
Hyacinth water treatment plant.
[bungston, Oct 04 2004, last modified Oct 06 2004]
||on first perusal this looks good.
||I like this idea, BUT also figure in Land Costs, Insurance and Labor for Construction along with Environmental Impact Reports and Potting Soil Product Certification to be certain one is not in fact creating what Government would later call a Superfund cleanup site, which also involves a really, really, really well lined 90 acre series of ponds - If there is leeching, 'contaminants' - whether real or imagined leave a very wide expensive door to lawsuits. After all that, double projected costs.
Emulsion is extremely fertile, so it would sell like hotcakes and have more appeal than normal postwaste treatment solids. I'll see if I can find a link to Morro Bay dredging operation - Pacific Gas & Electric has a new & improved power plant which is up for final consideration to replace one which is as much a part of the landscape as Morro Rock is. The dredging takes place to keep cooling waters of ocean which feed into plants turbines from becoming overburdened by silt, while keeping fishery and clarity more or less intact and relatively undisturbed within the channel - one wishes - unfortunately, nutrients and larvae fo with the cooling waters.
For what it is worth - are you familiar with municipal wastewater treatment facilities? Aquarium filters? A hybrid?
||At $6000 a month, how many people are running this thing? What sort of output (quantity of topsoil) do you expect?
||Oh, and what [thumbwax] said.
||OK, it was first pass at the numbers.
phoenix: Let's figure 2 maintenance workers, 1 engineer of some stripe. That's gonna run about $10,000 per month in wages alone, plus benefits (this is in rural SD, where nobody is well-paid).
thumbwax - I'm familiar with aquarium systems, and somewhat with municipal waste treatment. I have also watched, with great interest, a dredging operation for the past 1 1/2 years. it is a novel approach, using a series of holding ponds made from straw bales to filter the water. I've often thought about a rural home using a hillside system of retaining ponds, each with its own little ecosystem, to sequentially filter wastewater.
My primary concerns are making sure that money is well-spent, and getting a long-term plan in place.
Please note that this would NOT work for remediation of waterways that are damaged by heavy metals or most industrial chemical wastes.
||Good point about Heavy Metals - Selenium in Tulare Lake = nightmare. I think an ********* **** is the best solution - extremely simple and inexpensive - requires little maintenance and is something my pop is trying to bring to someones attention for such use, therefore I cannot name it - patenting at this stage would be counterproductive.
||Thanks for the links, thumbwax. Nice to find someone else here with similar concerns.
I'll post a link for the SD group that's involved in a lot of the remediation efforts around here.
||We'd still need to limit the behavior of everyone effluving into the lake. Selenium, yes; and also, say, clopyralid herbicides, which don't adequately break down in composting but do damage a lot of plants - legumes, solanaceae, etc - at very low levels. Seattle municipality has to test all its compost for the stuff and is requesting that the relevant herbicides be delisted.
||Once the lingering maleficient substances are dealt with (dodder & invasive mussels...), a Living Machine graywater plant is a pretty thing.
||Consider how rapidly water must cycle thru the pump to catch silt before it settles. You would have to filter a substantial percentage of the lake volume each day. This would sterilize the lake: tiny animals such as larvae and insects could not escape the intake and would be filtered out, as would algae. This would leave no food for larger animals. You might as well add chlorine, because you would have a swimming pool.
||I think the pumps are superfluous. Most lakes are fed by a finite number of streams. Streams are what brings agricultural runoff to lakes, unless you are right downhill from a feedlot. Develop the last hundred feet of the major feeder streams into concrete spillways with slots for installing your patented moss/sand thingbubs. Install them as described.
||Actually, in South Dakota, you could use water hyacinths in your spillway instead of wussy moss. Hyacinths are awesome filtering machines. You would have to import them or grow them in special tanks. They would not escape to become pestiferous because they could not survive the SD winter.
||Concrete slabs in natural settings to clean water? Maybe. Mini, endangered species, cement block apartment complexes? Who knows.