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Why Sewering the Rincon Won't Improve Ocean Water Quality

Letter in the Santa Barbara News Press

Summary: Sewer advocates misinterpret data from thier own studies of contamination from oceanfront septics push sewering even though it is likely to increase ocean pollution.

On this page:
Bird feces around a storm drain are posed to wash into the Rincon lagoon, causing tests to appear positive for human fecal contamination. Copious amounts of bird feces around a Rincon storm drain which leads directly to the lagoon a few feet away. This is several times the amount of feces found in the lagoon during testing. Without soil to purify them, these feces will all end up there.

Full text of first letter:


Rincon Point and the Three Million Dollar Disposable Diaper

As an ecological systems designer specializing in water and wastewater systems, I’m pleased to see a broad coalition rally to the clean water cause. Most of the content of the debate I agree with. However, at times it seems there Ian’t enough technical understanding to keep the discussion firmly anchored in reality. Lest we find ourselves taking multiple steps back for each step forward, I’d like to share some general ecological design principles, and use the question of how to improve water quality at Rincon to illustrate their application.


A fundamental principle of ecological design is to Consider the Whole Picture

The temptation to avoid the big picture is strong, because it is difficult. Of a hundred ways to make the ocean cleaner, only a handful will make things cleaner overall. It is easiest to clean up an area by sweeping the impact somewhere else. But often the total impact is then greater, because of the added impact of sweeping.


Heal the Ocean has done a service to the community by raising awareness of water quality problems so that everyone agrees that SOMETHING should be done. The water is dirty because of too much human disturbance. Building systems to relocate the disturbance (e.g. a sewer line) creates an ecological disturbance of its own: the production of miles of pipe, pumps, filters, electronics etc., digging up streets, sidewalks, gardens, and native burial grounds, and the ongoing consumption of electricity, chemicals, and burned out pumps, forever.


By removing the constraint of on site wastewater disposal from this area, the scale of and density of development is free to attain a much higher level—with a sewer line, the sky is the limit. Reduction of an ecological impact on water quality is being used to justify a system which has an extremely strong tendency to /increase/ ecological impacts of all kinds by spurring development. If property owners want more development, they can and should do it without exporting their waste problem.


Ecological Designs are Context Specific

What is appropriate in one place is inappropriate in another—everything depends on context. Are sewers bad? Is pooping directly in the ocean bad? it depends. Even on the high seas, flushing directly to the ocean sounds bad, but if you analyze it you’ll find that it is improbable the ocean could be affected. Does this mean it is OK to dump DDT in the ocean? It would have the same dilution initially, but re-concentrate in the food chain—so no. Is it OK to poop directly in the ocean when you’re in the harbor? No, the water is too confined. Pumping the sewage from the harbor to the treatment plant is better. Does that mean that if you live by the beach, you should pump your sewage to a treatment plant? It depends. If you live in Florida or Hawaii, the answer is yes. Florida has fissured limestone aquifers. The bedrock is a network of open, water filled caves which channel water rapidly without treatment directly to the ocean. In Hawaii, it is the same except the pipes are lava tubes. If you live on the coast in Santa Barbara, the ecological solution is probably to use a septic tank, because our climate and soil are optimal for septic systems. If the context is such that the septic tank is failing or likely to fail, it may need some help in the form of reducing the flow or enhancements to its treatment capacity.


Santa Barbara just approved a new septic tank ordinance, citing studies from Florida and Hawaii and saying “we cannot assume Santa Barbara is any different from the rest of the world.” But septic effluent which travels ten miles in a day in Florida might move a foot in Santa Barbara. Inspecting septic tanks to make sure they are working optimally is a good idea. Hooking Santa Barbara houses to sewers because septics don’t work in Florida is not. Santa Barbara would be bucking a promising national trend towards effective on-site treatment by supporting sewer conversion.


In Marin’s Stinson Beach, there is a half-mile long sand spit a hundred yards wide, with the Pacific on one side and an ecologically sensitive lagoon on the other. It is all sand, and no point is even ten feet above the water. The spit is covered with large houses, all on septic tank/ sand mound systems, all inspected annually, all working. This is a more appropriate inspiration for coastal problem areas in Santa Barbara.


The purification capacity of soil for fecal bacteria is astounding. According to tests by the World Health organization, you could fill a dry pit with feces and it would not affect a creek or ocean twenty feet away—they found almost no lateral migration. The same studies showed maximum extent of bacterial plumes from feces in flowing groundwater of forty feet. Tests of land treatment have found it to be effective against viruses, something treatment plants are not very good at (references and the calculations behind the paragraphs below).
Over six hundred pounds of feces are treated by Rincon Point septic tanks every day. Using data from the Lower Rincon Creek Watershed Study by Santa Barbara County Public Health and Heal the Ocean, I did a “back of the envelope calculation” to convert their findings on lagoon contamination from the obscure units given (79 fecal coliform mpn/100ml) to the more easily grasped half-teaspoon of human feces in the 30,000 or so gallons of the lagoon. This study produced no firm evidence that the septic tanks are contaminating the lagoon. It does show that IF they are, the maximum amount of contamination is still well under the standard for swimming. Fecal matter would come out of failing septics in a fairly steady stream. The study noted that forty percent of the human feces were from one sampling event—so it is possible that one casually tossed diaper is costing Rincon homeowners three million dollars..


Of the 74 septic systems at Rincon, If any are polluting the lagoon, it can only be a few partly failing systems. According to the sewer proponents’ own study the amount of nasties entering the lagoon is at most /four thousandths of one percent/ of what goes into the septic tanks. If hooked to the sewer, 100% of the sewage would go into the ocean with enough chlorine to kill the fecal coliform indicator bacteria, but not enough to kill all the viruses. If there is a very hard rain, power failure or pipe break once every eighty years, the sewage treatment plant will dump more raw feces from Rincon point into the ocean than eighty years worth of the maximum contamination the septics could be causing. A sewer will also increase the amount of effluent, by removing incentive for indoor water conservation and enabling more building. Not a great water quality improvement, and certainly not cost-effective at three million dollars—to clean up at most a diaper a month worth of feces.


In literature supporting sewer conversion, Heal the Ocean states that “it’s like sweeping ones house—getting all the dirt and dust into one pile (getting the septics into one disposal area) then picking it up into a dustpan (sewage plant).” They further state that the key to their program is their long term vision that 100% of sewer effluent will be reclaimed.


The spirit is commendable but there are technical glitches. First, septic tank effluent is a special kind of “dust” which is harmlessly returned by soil to nutrient and water cycles precisely if the concentration is not too great, as their study shows is happening now. Getting it all “into one pile, ” i.e., too concentrated for soil to deal with, is exactly the wrong thing to do with a material of this type. Second, the vision of 100% wastewater reclamation (which is still under investigation) could only be attained with aggressive sewer flow reduction. What are you going to do with several thousand acre-feet of reclaimed water during the rainy season? Heal the Ocean’s goals would be better served by aggressively fostering effective on-site treatment wherever feasible—any other approach is plain bad design.


Choose the Most Inherently Simple Solution and Implement It as Well as Possible

I was informed by Heal the Ocean that on-site treatment was probably ideal, but it would take too long to implement. The most simple, cost effective, and immediate measure possible would be for Rincon homeowners to conserve water indoors, and divert greywater from their septic tanks. The load on Rincon septic tanks could easily be reduced 80%. The impact on the ocean would be reduced more, say 90% (not only is the flow smaller, but the remaining flow receives much higher treatment as it takes longer to pass through septic tank and soil). This would eliminate most capacity problems and could be done for a few thousand dollars per house. Any water quality improvement would occur immediately. The techniques tend to be far simpler and cheaper, and nothing begins to compare with flow reduction for improving overall impact.


This would increase the effectiveness of the systems from the 99.997% (minimum) measured by the study to perhaps 99.9997%. If the remaining problem septic tanks (if any) were then identified, they could be improved with sand mound or other proven on-site treatment systems at a cost per house which was substantially lower than the $40-$60,000 for hooking to sewer. The overall cost for the community would be dramatically lower—maybe $500,000 instead of $3,000,000 plus. The contamination of the Rincon would be reduced without making someplace else dirtier, improvement could start immediately, very little electricity and no chemicals would be required, roads would stay intact...


A colleague with extensive experience constructing wastewater treatment facilities says they are 10% technology and 90% politics. The intense desire to DO SOMETHING about water quality may push Rincon Point sewerification onward. When Heal the Ocean finishes studying sewage reclamation and finds out the amount of flow reduction required to make it feasible, that SOMETHING may turn out to be an expensive education in the way NOT to take care of areas where septic tanks work fine with a little care.

Art Ludwig

References & further reading

Sewer battles in Bolinas and Monte Rio (a great, humorous article by Lloyd Khan)

The National Small Flows Clearinghouse (assistance with on-site treatment)

A couple Case Studies about wastewater treatment, available through the National Environmental Services Center

The World Health Organization on pollution plumes from dry pit toilet (CIF graphic, large file)

The World Health Organization on pollution plumes from pit toilet in groundwater flow (CIF graphic, large file)

Removal rates of land treatment facilities (CIF graphic, large file)

Rincon Point Sewer Calculations

5/20/99

30.7

Average Lagoon fecal coliform concentrations by date, mpn/100ml (from lower Rincon Creek watershed study by SB Co. Health and Heal the Ocean)

5/24/99

60.6

3

5/25/99

35

5/26/99

110

5/27/99

102.4

6/1/99

144

6/4/99

72

a

79

Average Lagoon fecal coliform concentrations for all dates, mpn/100ml (calculated from data above)

b

20%

Percent of (a) which is human (a guess, loosely based on the 20% human matches from study, which was conducted in a way that does not give a direct quantitative relationship).

c

16

Average concentration of fecal coliforms of human origin mpn/100ml (a*b)

d

1

Approximate conversion factor from fecal coliform mpn/100ml to parts per billion of feces (see assumptions below)

assumed:10 million coliforms per gram of wet feces (dog=23 million, human 13 million...)

assumed: 1000g feces/person/day (one source gave 1113g as the average daily production of feces)

e

16

Average concentration of fecal matter of human origin in ppb (same as mg/m3) (c*d))

32,076

gal

f

122

Approximate volume of lagoon in m3. It was approximately 60m long, 4.5 m wide and .5 m deep, average at the time of the study

g

1926

amount of human fecal matter in lagoon (mg) (f*g)

0.07

oz

h

2

amount of human fecal matter in lagoon in grams (g/1000)

i

74

Number of houses (from study)

j

4

Average number of people per house (guess)

k

1000

Daily feces production per person, grams (one source gave 1113g as the average daily production of feces)

kk

20%

Percentage of septic tank effluent which are closer to the lagoon than the ocean (guess)

131

lbs

l

59200

Grams feces introduced into septic tanks near the lagoon per day (i*j*k*kk)

Assumption: the lagoon water is changed each day by flow (this is highly variable)

m

0.003253%

Human feces in the lagoon as a percentage of human feces introduced to tanks per day (h/l)

n

99.996747%

Minimum percentage effectiveness of septic tanks for preventing contaminated water from going into the lagoon, assuming 100% of human feces in the lagoon ARE from septic tanks

o

99.999675%

Postulated effectiveness of septic tanks if flow is reduced 80% (n *1/90%)

p

1

Approximate number of tightly rolled disposal diapers required to contaminate entire lagoon to this level

q

519

Approximate number of days one person's bowel movement could comtaminate the lagoon to this level

s

30743.64

Number of days of maximum septic tank contamination equalled by one day of 100% raw sewage flow (l/h)

t

84.23

Number of years of maximum septic tank contamination equalled by one day of 100% raw sewage flow (l/h)

u

3,000,000.00

Cost of project in dollars

v

30

Lifespan in years

w

21085.33564

Maximum grams of feces kept out of the lagoon in thirty years h*365*30

4,034

$/oz

x

142.2789777

Dollars per gram u/w

 

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