I have a couple of questions.

1) Aren't septic systems supposed to be sealed or do all of them just openly flow into the aquifer?

2) It it does flow into the ground water, isn't some of the material filtered by nature?

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I was right.

No and yes...
Here is 1 of many designs for a septic system, but they all flow into a drain field by design as far as I know.



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Specializing in sarcasm and condescending rhetoric since 1971.

From what I know about septic tanks and the video above I think the big problem is not the tank but the pipes coming from the house to the tank. These pipes are old and rotten and leaking the "effluent" in the ground without the benefit of the bacteria in the septic tank. This bacteria breaks down the crap and breaks down some of the toxins. The outlet from the septic tank leaches into the ground via the drain field and, yes, hopefully is "filtered by nature"

Ah "septictank", that's an old native american phrase for "magic box in ground". 

OK, mass balance people:

50 gals of dirty water goes in, 50 gals of dirty water comes out.  

(btw - I used 50 gals because that's about how much water a person uses each day, check your water bill)

The tank has a baffle in the middle (see worksux's diagram) to keep the solids out of the drainfield,

and an invert to keep the floatables out of the drainfield.  Prevents clogging.

The tank itself is a bioreactor of sorts, it kills viruses and fecal coliform bacteria so it doesn't transmit disease.

That's what it's there for, to protect human health, not the environment.

Also, to some extent, it biodegrades solids to disolvable substances.

So, for example, if you unrinate out 11 grams of nitrogen as urea (yep, that a daily median value)

it get degraded comes out of the tank as 11 grams of nitrogen as ammonium. 

No reduction in nutrient load.  

Sure, there are advanced system that do some nutrient reduction

(and there is some (small) amount of natural denitrification that also counts as reduction)

but advanced systems (in my experience) get broken and become non-advanced pretty quickly

and since they're expensive to repair and no requirement.... you get the idea.

 

Another fun fact, note the flow of water in Rocket's diagram

from the drainfield to the aquifer,

and then back up the well and into the house

I don't know why people complain about drinking reuse water,

(https://www.orlandoweekly.com/Blogs/archives/2018/04/06/rick-scott-rejects-toilet-to-tap-proposal-to-pump-treated-waste-water-back-into-aquifer

if, you're on septic and shallow well, you already are. 

(check the nitrate value for your well water from when the well was tested when you bought the house, the test is a requirement)

 

So, septic tanks have a place in life like everything else.

If you live on 10 acres, 19 miles out on the end of a dirt road,

it's impractical to pump your sewage to the treament plant.

If you live on a quarter acre plot surrounded by hundreds of other identical homes,

you/we need sewer.

Oversimplified again, of course, but FWIW.

 

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Edited: 04/25/2018 at 05:53 AM by tom

As long as the discharge from private septic drain fields percolates downward deeply into the soil the nutrients are biologically consumed and almost completely sequestured in the soil.  The same is mostly true for any leaks upstream of the tank as long as it too percolates downward.  Just put your drinking water well a good distance away, or very, very deep.

It is my belief based on personal observation that the problem arises due to periods of extreme heavy rain fall where our flat terrain and sandy soil becomes totally saturated and downward percolation ceases.  Standing nutrient rich surface water then runs off directly to the storm water infrastructure and typically straight to the lagoons.

Building Codes have also been updated that require drain fields be more elevated and porous to prevent clogging and eventual failure.  The problem with these newer fileds is they tend to drain a bit more horizontally, especailly in flooding conditons, resulting in increased nutrient rich storm run off.

There are also many older canal homes that were built with septic systems, where downward percolation naturally resulted in leaching to the canal.  Even when these septic aystems are replaced with sanitary sewer that leaching will persist for many years.

It has also been my observation that extreme heavy flooding rains have become more frequent and consistent locally and aren't giving the lagoons a opportunity to recover as they have in the past.  It doesn't help that Brevard County santary sewer sytems are leaking at an increasing rate and provide a near continuous nutrient flow.

I've been observing the Chain of Lakes strom water retention system North of Titusville since its creation, and believe that is a viable solution.  We need many more such installations just like it, but in high desity areas where they're needed the most, space simply does not allow it.  I hate to say it, but a prolonged and severe drought that spikes lagoon salinity is our best hope for a recovery.  Any such recovery would of course be short lived though.       

Diffusion is not just vertical as you imply in paragraph 3.

Thanks Tom.

"As long as the discharge from private septic drain fields percolates downward deeply into the soil the nutrients are biologically consumed and almost completely sequestured in the soil. "

And, if that was happening, it wouldn't be showing up in the Lagoon. 

See Barile paper, previous page, this thread.  

 

edit:  and T, I should use you as my editor all the time, saves zeros and ones.

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Edited: 04/25/2018 at 07:26 AM by tom

Mangroves do fine low salinity. The water just needs to be salty enough often enough to stop competing species in natural settings. If it stays fresh permanent then it will transition from Mangrove to shrub swamp or herbaceous marsh depending on hydrology and nutrient availability (like the sawgrass-mangrove gradient down south). 

As for the general trend. The lagoon is getting saltier (speaking of the water between SI and Haulover). More development means more flashy, so a less reliable supply of poorer quality water. You get spikes of fresh (loaded with nutrients) and then long evaporation dominated interludes. This increases the residence time of water and promotes plankton growth. Rain fall patterns have also trended toward having longer more intense dry seasons punctuated by events (e.g. Fay, Irma). Some of that is Atlantic Multidecadal Oscillation related with a layer of a warmer climate layered on top. A full narrative would be TLDR for a forum and probably range into the realm of "but I slept at a Holiday Inn Express last night".

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Edited: 04/25/2018 at 05:21 PM by scombrid

http://webapub.sjrwmd.com/agws10/edqt/

There's a lot of data here. A little cumbersome to search at first until you get used to navigating.

I just did a quick download from a station that is in the Banana near 520 and graphed out salinity from 1987 to March 2018.

Can't paste the graph though.

Salinity was 10-20 ppt in the wet 1990s.

Got up into the to almost 35 ppt in the 2000-2001 drought.

A wet 2001-2005 period pushed it back down to around 15.

It went up pretty steady there-after with the exception of the Fay blip. Fay dropped it from 30 to 17 in one shot but then the weather got dry again. By Jun 14 it ws pushing 40 ppt. That hyper-saline condition is not good.

Somebody in the know probably can find stations that go back further than the mid-1980s.

That is the open BRL. Your mileage may vary depending on location. Mosquito infested places like Sykes Creek and the way north BRL used to stay really fresh for a long time during wet periods. All of our canals and ditches mean they get fresher faster when it does rain and saltier faster when it doesn't rain.

Oh, another one to add to the mix. People running their irrigations wells constantly. Those shallow wells are pulling water that should go into the lagoon.

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Edited: 04/25/2018 at 05:24 PM by scombrid

scombrid-sent you a PM

Hey scombrid -

Was thinking about your well/groundwater statement.

I wonder what the percentage of surficial aquifer vs florida aquifer those wells are?

Surficial wells would be subtraction from the baseflow but deep/floridan irrigation might be addition, depending on ET rate of course (?).   

Also, I've always wondered what the localization / focusing of stormwater infiltration via retention/detention does to groundwater flow and quality.  Similar to runoff quality(?).  

Just random thoughts, adding to the mix as you said.

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Diffusion PDE

Interesting salinity trends. The lagoons in SFL have flashy inputs, to the extreme of course. Way too much freshwater in wet season and not enough dry. Most of the big projects are targeted towards addressing that, and nutrient loads.

Now, what about temp?

I remember scombrid's mention of increasing overnight lows. That's got to have a big effect on lagoon ecology, as warming water maybe should reduce dissolved O.

After the heavy rains last Sunday (22 April) the canal behind my CB home went from a light spicy mustard yellow color to a rootbeer shit-brown color....I also noticed what looked like a thick red paint spill on the water and after a closer exam I found it was red stringy algae with the added bonus of a dead catfish.

Today there are multiple dead fish at the head of the canal and the color of the water is now red. I know there is some action in work from our local officials but the bottom line is a lot more money needs to be dedicated to the IRL. I write letters and get canned responses. It seems that the only way to get through to these people is by some kind of social media, viral event (I can't believe I'm using these words). Maybe a little "Fight Club" style operations. No destruction, no violence, just events or local antics that could get some national/state attention. I don't think there would be anything better than to see a politician sweating in front of multiple cameras explaining why the money that should be used to stop polluting the IRL: new sewer sys, removal of septic tanks, runoff management, use of fertilizer, etc. is being diverted to: upgrades to the Viera Regional Park's soccer and lacrosse fields($5M), an elections support complex (~$2M) that is not being used, an indoor multiuse sports arena and hotel project in Titusville ($7M). It seems the list is endless.
WE LOCALS NEED TO STAND UP AND BE NOTICED AND HEARD!
Man, I'm pissed...
1st rule of Fight Club is..........

yea the new downtown cocoa beach looks nice, but would have preferred the old if the $$ addressed those ^^pics above^^ makes me sick to look at!

I wonder if they will cough up enough to put up no swimming/nadar signs....

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I troll 2L.com to be a better person in real life

How appropriate to this thread!

Brown 25.

In an attempt to decrypt the wiki article, the diffusion equation says that the rate of change of density (of groundwater in soil in this case) at any point with respect to time is dependent on the the rate at which that density changes with respect to position. Stated even more simply, liquid tends to spread out, though that won't help you predict the amount of flow; time rate depends on space rate is both elegant and non-trival and the solution to a differential equation is a function or an approximation thereto.

Note that for groundwater you would have to add a gravity term.

Interesting read on septic and sewer issues

FLA TODAY Article on Septic and Sewage