Septic Systems

**John:

From Rhode Island:

.5.2 Calculating the flow trial volume
**Normal wastewater flows vary over the course of a day, peaking during the
morning and evening hours when people are most likely to use the kitchen, bathroom and laundry facilities. The greatest flow that may enter a system during an hour of time is called the peak one-hour flow. As it is typically the most stressful condition experienced by a system, the peak one-hour flow is also the condition that the flow trial is designed to approximate (i.e., peak one-hour flow = flow trial volume).

An examination of the literature indicates that peak one-hour flow can be
estimated as 12 times the average hourly flow or half the daily flow. Systems in RhodeIsland are designed based on the daily flow (i.e., design flow = daily flow), which can be calculated as 150 gallons per bedroom per day.10 Therefore, flow trial volumes can be calculated as half the design flow or as the number of bedrooms times 75 gallons.

Table 5.4 indicates flow trial volumes for homes relative to number of bedrooms and design-flow volumes.

**Table 5.4 Minimum Flow Trial Volumes Relative to Number of Bedrooms and Design Flow
Number of Bedrooms/ Design Flow (Gallons/Day)/ Flow Trial Volume (Gallons)
**2 300 150
3 450 225
4 600 300
5 750 375
6 900 450

My comments:

As you can see, I’m the ultimate sceptic. On house issues/repair costs that I have verified/seen the need for, I feel confident with estimates from good contractors. Using a full day volume for a flood test is still something I’m not confident with, even when from septic tank installers. Maybe less confident from installers as they have the most to gain!!! This culture is increasingly “All about the dollar” so I trust less and less. The full load test may generate a job that does not have to be done- good for the installer and makes the inspector look real good to the purchaser.

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** 3 Bedrooms X 75 = 225**

This trial amount for a 3 bedroom house is more than I test with.
I suggested only 200 gal. Whats the problem?

It appears your post backs up my methods. What I’m I missing?

John:

After a bit of research, I’m confused with the last series of posts and want to clear things up for the board. You posted:

**"If you look up what a non aerobic system is suppose ****to be able to process in a day (three bedroom - two bathroom house), and then run the water in the house to just under that threshold, you have now flood **tested that septic system.

From your info, I was assuming the full day’s flow would be 200 gal. From the RI chart (which I found later in our postings), the assumed daily flow is 450 gallons so just under that threshold is 400+ gallons.

I also posted about a full day’s flow for the flood test to which no corrections of my assumptions were made:

"To load a system with a full day’s 200+ gallons in 20 minutes is not the natural flow to the leach field which is usually spread out over 16-18 hours from 6 AM until 12 AM. A field may easily absorb 60-100 or so gallons from early morning use of flushes and showers but floods when the total day’s load is dumped on it in 20 minutes. No field is designed to accept the daily load in 20 minutes"

**"Using a full day volume for a flood test is still something I’m not confident with, even when from septic tank installers."

So, for the board, “Go to a chart or remember 150 gallons/bedroom and flood test at half that rate or 75 gallons per bedroom.” seems to be the operational guideline.**

I am glad you see that now.

75 x 3 Bedrooms = 225.

My recommended post was for a 200 gal flood test.
You and me now agree.

Thanks.

My septic test is this:
50 gallons X how many bedrooms in house.
while this is occuring i open the tank to be sure the dye flows into the tank itself. Then while the test is being done I walk the feild 3 times probing various areas. I also walk into woods and out into streets to see if the ‘grey water’ is flowing elsewhere. if there i a creek i walk it roughly 2000 feet or so to see if dye it seen.

How often has this happened to you? My concern with septic tests is that the seller will make a case that I caused the failure by shock loading the system. I would not be suprised if the courts took up a silly case like that.

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In order to prove I was wrong, the seller would have to hire a licensed
Septic Installer to make a written statement, with his license number on it,
that the old Septic System was OK. The problem with that is, these guys
are instructed to go by today’s code ONLY. They have no option.

If you read all the qualifications of what makes a system stand up to
today’s code, an old system will fail 99% of the time.

If the seller calls the installer out to his property to prove me wrong,
and then finds out that his system fails today’s code, the installer
can then place a time limit and force the seller to upgrade to a
new $6000 aerobic system, on penalty of a fine. The installer
is mandated to turn that seller’s name over to the county for
having a failed system in need of repair. So there is a lot at
stake, if they call an installer out and try and prove me wrong. If
a seller fails in their attempt, it forces a $6000 repair down
their throat.

Most Realtors will tell the seller to just let it go and wait
for the next jerk to buy the house, as is. The Realtor
is not going to make a commission, unless they find another
lucky soul to buy the property. Why go after me and delay
the sale? Sometimes people’s greed works to protect
you.

If the installer certifies that an old system is OK, and it does
not meet today’s code… the installer knows he will be the
one who has to buy the new $6000 system and loose his
license for negligence. It takes two signatures to certify
a system in Texas.

So you see, it is not as easy as it sounds, to attack my
findings.

I just had a situation where a builder wanted to sue me for
failing an old septic system. I simply told him to find a license
installer who would stamp his license number on it and I’m
dead meat. He never found anyone willing to do it.

Read the above numbers again in the previous post, it proves
that my test is within the normal ranges, and others do the
same type of testing. They have been dong it for years and
that is why these numbers have been written as an industry
standard.

Have you ever inspected a septic system?

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Nope, I defer to the reputable installers in the area. Heck, most of the time the seller provides a “septic inspection report” before I arrive. Most of those “reports” are nothing more than a measurement of the sludge and scum levels and checking the appropriate box for “Are there any indications of system failure”. One of the installers that I defer to says that those types of “reports” are done by those who lack enough knowledge to properly inspect them, typically pumpers and the occassional home inspector.

When you speak of installers being forced to inspect by code, is mandated by the state of Texas or is it a federal policy?

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I can only tell you what I know about Texas, but the pressure is building from
the EPA federal level and puts more and more pressure on the local govt.'s

Inspectors here have been given the SoP to do visual inspections, but the
installers do not go by our SoP.

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