AboutDavid L. Russell, PE Expertise I`m a Chemical,Civil and Environmental Engineer and have a number of projects in all phases of the environment.
I have worked in the chemical industry and am active in professional societies, and am currently on an industrial wastes committee for the Water Environment Federation, and have taught courses in remediation in the US and abroad.
I have written one book on Remediation of petroleum Contaminated Sites, and have a second book on PRACTICAL WASTEWATER TREATMENT to be published by John Wiley in September, 2006. I've also written over 30 articles on various elements of environmental problems and cleanup. Most Recently, I have addressed a NATO Scientific and Techical Conference on Ecoterrorism, and have worked with the same group on remediation of sites contaminated with Chemical Warfare Agent materials and othe materials as well. . I can answer q`s about Chemical and Environmental Engineering, land development, air pollution, water pollution, soil and water cleanup, combustion, international environmental problems, industrial processes chemical processes. Civil and Environmental and Chemical Engineering. Overall, I have over 35 years of experience in this area. Note: I do not answer homework questions
Experience I love work in the third world and developing areas
because it is challenging and one can get a sense of accomplishment.
My parents live on a small man-made lake (55 acres) fed by a spring which doesn't get the circulation it needs and gets quite weedy (this year, the whole lake almost) and at certain cove-like areas of the lake it seems very swampy. It is never very clear and sometimes gets quite green. It was tested by a company called SNR and they treated it with Reward Herbicide, but obviously that didn't work.
Despite the testing, I was wondering about the safety (bacteria, amoeba, etc.) of swimming in the lake as no one seems to go swimming there for the most part, if there are safer chemicals that can treat a lake like that or if it is recommended. Also, is there a non-expensive way to circulate at least a little cove-like area to prevent it from getting swampy, the fountains are too expensive? And finally, is there an easy way to get rid of the weeds manually?
Thank you for your time
Rob
Answer Rob:
you are in a tough situation. The problem you describe with the growth and plants are caused by nutrients, principally phosphorous in the water.
The first thing I would try is to apply ferric chloride or aluminum sulfate to the water. That should precipitate the Phosphorous, but it may take a lot of thc chemicals to accomplish that. You might want to run a jar test first to determine what it will take.
Copper sulfate will kill the algae but it's a toxin besides and you might be in trouble with the local enviornmental authorities if you applied it. It is, however, effective, but it's also a fish toxin in the right concentrations. IT make take several tons of alum and/or copper sulfate to enable you to clear the lake, and that raises a number of questions and technical challenges like how are you going to apply the chemicals. Copper sulfate is considered a hazardous chemical and the price of copper has gone up substantially.
I don't know about specific pesticides or herbicides. The problem is maintaining the right concentration of the herbicide for long enough to be effective. Check with the EPA on their webside for approved or registered herbicides. It might help to identify the type of weeds and algae in the lake.
There will be lots of natural bacteria in the lake, and while it is safer than going for a dip in a septic tank, the water quality is not very high because of the algae and the nutrients. You could probably swim very safely in the lake, but I would not want to see you go swimming with open cuts, and I would wear swim goggles or a mask which would be even better. Don't drink the water either.
The problems you describe with the weeds are difficult. There are some underwater cutters, but they tend to be expensive. If you want to circulate the water in the lagoon consider a compressor and bubble air through the water. You will need a pound of pressure for every 2.3 feet of depth the outlet is buried under the water surface. A 10 or 15 foot depth might give you enough circulation and be relatively inexpensive to operate, but that depends on how much you run the compressor. In some cses, you can use a low pressure blower operating at about 8 psi. With a depth of about 10-12 feet that shoudl be about right when you consider the piping losses. Use large pipes (plastic ) and weight them down with bricks or something else tied to the pipes. The bubbling effect will help circulate and aerate the water.
A 55 acre lake is not inconsiderable volume of water. Your problem is probably either nutrients but I would also ask the neighbors or the local sanitarian to check the septic tanks of the residences around the lake with dye testing. If the dye shows up in the lake you have a manmade sewage problem with leaks into the lake.
I don't know if I've solved your problem, but maybe I've pointed you in the right direction.
If you need more help, write back.
