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PMP Associates Blog

Posts Tagged ‘Sanitary Code’

How to design a Septic System – Understand the Sanitary Code

Wednesday, February 10th, 2010

Since the late 1970′s, as a Civil Engineer, I have been involved with the design of Septic Systems, including the training of other young engineers.

If I was limited to only one piece of advice, it would be:

Understand the Sanitary Code!

In Massachusetts, the Sanitary Code was issued in 1978 under 310CMR15.00 and commonly called “Title 5″. A major revision took place in the mid 1990′s with further revisions during the last few years. In addition to the Code changes, the State has been issuing “policies” that clarify the Code and allow for the use of various “innovative and alternative” systems and components.

I have never subscribed to the “You can’t teach an old dog new tricks” mentality. As each Code revision is published, I and my staff of civil engineers become familiar with the changes and new requirements. As new technologies are approved (for both remedial and general use) we get technical data from these companies, including in-house demonstration seminars.

I can’t understand how a designer will insist on using a conventional pipe and stone leaching system when there are so many choices available that would reduce the cost of the system. Well, maybe I do understand, they either don’t want to change, or, they are cutting their costs & fee and limiting the time spent on preparing the design plan. Some people like vanilla, but there are other flavors available and while you might pay a little more, there are added benefits in the long term.

Think of this as a round peg in a square hole. Depending on the size of the peg, you might be able to make it fit. But one size does not always fit all!

Do you remember Mission Impossible? At the beginning of the program, the team is selected from the stack of available members. While the design of a septic system is not an impossible task, having the right “team” of system components should be the ultimate goal.

In order to select the “team”, you need to understand the Code!

“Do-it-yourself” Septic System Design

Wednesday, January 6th, 2010

Having trouble with your Septic System? Can’t take a shower and run the washing machine at the same time without having to clean-up a system back-up? You have a nice wet green area in your yard when the rest of the lawn is brown? Do you think it is time to replace the old Septic System?

Why not “do it yourself”?

While some of the following information could apply to other States, the focus of this Blog is to address residential septic systems in Massachusetts.

The first step is to understand what is a Septic System, which is also known as an on-site sanitary wastewater disposal system. The Massachusetts Department of Environmental Protection (MA DEP) maintains a website with lots of information. The trick is navigating through the site (link to the main DEP Septic System page)  to find the answers you need. In Massachusetts, the design of septic systems is controlled by the State Sanitary Code (310 CMR 15.00) which is also known as Title 5 which can be obtained at this MA DEP Septic Systems/Title 5 link . Each community can also establish local regulations that have to be followed. You should check with the local Board of Health office.

Before you get started using the Code to do the design, let’s become familiar with the basic septic system components.

Septic Tank & Pump Chamber

Septic Tank & Pump Chamber

Sanitary wastewater leaves the house through the building sewer and flows by gravity into the Septic Tank. In some instances, the design requires a pump to move the septic tank effluent to the leaching system (also know as the soil absorption system or SAS)

The effluent leaving the septic tank and/or pump chamber has to be piped to a Distribution Box (“D” Box) before entering the SAS. The Distribution Box  is designed to allow the effluent to be distributed evenly into the leaching system by gravity (there are pressure dosed systems that do not use a “D” box).

Gravity Distribution Box with a force main inlet pipe

Distribution Box with force main inlet pipe

Distribution boxes are typically made of concrete and are available with multiple pipe openings and sizes.

The SAS or “leaching area” allows the distributed effluent to pass into the ground.

There are multiple types of systems and components that have been approved for general use in the design of this system component. The decision to use a pipe and stone leaching field, pipe and stone leaching trench, chamber system or other type of system should be based on the specific site conditions and property constraints.

No Aggregate Chamber Field

No Aggregate Chamber Field

The MA DEP web site also published a series of technical design documents that are available at this Guidance and Policy link.

Now that you are more familiar with the systems components and have copies of the regulations, there are a few more steps that need to be accomplished before you can work on the design. You will need to prepare a plan of your property to show the existing house as well as the site features, such as the driveway, trees, swimming pool, etc. This plan needs to show your property line (your deed will describe your property and may even reference a plan that shows your lot lines). This plan also needs to show topography (your town may require the topography to be based on a national datum and not an assumed elevation) and spot elevations at certain locations.  It is also helpful to know the location and invert elevation of the building sewer pipe at foundation as well as the location of your water service and other utilities (gas, electric, CATV). If you or your neighbors have a well (drinking water and or irrigation well), then they (all the wells) also need to be located and shown on the plan.

Topographic / Existing Conditions Plan

Topographic / Existing Conditions Plan

Do you have wetlands within 100 feet of your property or where the new septic system would be installed? Then you will need to have the edge of the wetlands determined, located and shown on the plan. Some towns have local Wetlands By-laws & Regulations which are more stringent that the State Regulations, so it may be best to contact your local Conservation Commission office.

Now that you have your worksheet plan, you can determine what area is available to locate the new septic system. The Code has a list of set-back distances that need to be followed, such as 10 ft. off the property line, etc.

The next step will require the services of a MA licensed Soil Evaluator to perform the official soil evaluation and percolation testing. This testing is witnessed by the local Board of Health and typically involves submitting an application along with a fee payment. The testing will involve the excavation of several deep (10 ft. plus) holes in the proposed system location, so you will need a larger backhoe.  You (or your excavating contractor) will need to obtain a “dig-safe” number and a Trench Permit (issued by the town).

Soil Evaluation

Soil Evaluation

The soil evaluation will determine the depth and suitability of the soil, the elevation of the estimated seasonal high groundwater and the percolation rate. These items are all used in determining the elevation of the system components as well as the size of the SAS.

If you have a property that has high groundwater and the good soils are saturated (can’t perform the percolation test), then a soil sample can be taken to a State Certified Soils Lab to perform an analysis to determine the classification for establishing a percolation rate. This is only allowed for system replacement when no increase in flow is proposed.

Speaking of flow, the Code requires you to use a design flow based on the total number of bedrooms. If you have a house with more than 10 rooms, you are required to do a mathematical calculation to arrive at the bedroom count. The Code uses 110 gallons per day per bedroom with a three bedroom minimum design. Some towns require a higher design flow amount.

Now you can take all of this information and do the design for your septic system! The Code has a listing of all the items that must be presented on the design plan and some towns have additional content requirements.

In Massachusetts, the final design plans that are submitted to the Board of Health for approval must be prepared by a Registered Sanitarian or a Registered Professional Engineer.

Maybe the “do-it-yourself” method is not a good idea.

However, by knowing what is involved with this process and the multiple options for replacing a failed septic system, you can use this knowledge in hiring the Sanitarian or Professional Engineer who will work closely with you in preparing a final plan that is best suited for your property.

12 Steps to replace a Septic System

Saturday, April 12th, 2008

For those non-city folks that rely on a septic system instead of a city sewer, having a failed septic system is a major headache. It is amazing to hear the horror stories, as well as, the vast amount of mis-information being circulated about septic tanks, leaching systems, septic system repair costs, etc.

With over 30 years of experience in the design engineering of subsurface sewage disposal systems, commonly called “Septic Systems”, I’ve prepared this easy to follow 12 step outline as a guide in replacing a Septic System. There is one very important pre-qualification before you start, you need to retain a qualified professional civil engineer or registered sanitarian. I have to stress the word “qualified”, unless you want to enjoy being the leading role in the next release of “Horror Stories from the Leaching Field”. Take the time to do a little homework, such as going to your local Health Board office and asking what civil engineers are designing septic systems in your Town and whose design plans are typically approved without having to be sent back for corrections and revisions. Once you get a few names, do a little research on the web, Better Business Bureau, etc. Then you should contact these civil engineers and talk with them about your problem septic system and ask for a written proposal that will outline the tasks and costs. Just like you wouldn’t eat a rotten piece of fruit, if you don’t have a good feeling about a particular civil engineer, then do not hire him!

Now you are ready to go forward with the 12 steps.

  1. A test application is submitted to the local Health office (some States, like Rhode Island, control the testing, etc. so the application would have to go to a State agency.)
  2. You hire an excavation contractor to dig the test holes. If you do not know a local excavating contractor, then your engineer should provide you with a few contact names. (FYI – by hiring a contractor for the test holes, you are not making a commitment or obligation to hire him to install the replacement septic system.) This excavation contractor will need to follow local / state safety regulations (such as obtaining a “dig-safe” number and having the underground electric, telephone, CATV, gas, etc. located before the test holes are dug.
  3. The engineer coordinates with the Health Agent, excavating contractor and you (the client) to set the testing date.
  4. The engineer performs the official deep hole soil evaluation and associated “perc” percolation testing. Soil samples may have to be obtained and taken to a lab for further testing. The engineer prepares the official forms (soil logs) and submits a copy to the local health office and to you.
  5. The engineer performs a limited existing conditions topographic “topo” survey of your property where the replacement septic system is proposed. (FYI – Unless you have a small lot or do not know where your lot lines and/or lot corners are located, you typically would not need to have your property line surveyed.)
  6. The engineer uses the results of the soil evaluation, perc. testing, topo survey in combination with the current and anticipated building use (number of bedrooms, garbage grinder, etc.) and State / Local Sanitary Codes to design a replacement septic system for your property.
  7. The formal design plans (with the original seal and signature of the professional civil engineer) and construction permit application are submitted to the local Health Agency for review and approval.
  8. The engineer provides you with additional copies of the design plans for you to submit to licensed contractors to obtain a price quote / bid.
  9. Once you have selected a contractor, he coordinates with the local Health Agency (to obtain the permit) and the engineer, prior to starting the work.
  10. The Health Agent visits the construction site as the work progresses to observe and confirm Code compliance.
  11. The engineer, in most States, must visit the construction site to observe the critical construction stages, make measurements and prepare a formal plan showing the completed “as-built” septic system. The engineer submits a copy of this plan to you and the local Health Agency along with a signed compliance statement. Some States also require the contractor to sign and submit a compliance statement.
  12. The local Health Agency reviews the “as-built” plan, etc. and issues a “Certificate of Compliance” which signifies that the replacement septic system as installed is in compliance with the State and Local Sanitary Code.

One other item, if you have wetlands on or near your property and the anticipated work will be within 100 ft. of these wetlands, then additional permitting will be necessary before you can have the replacement septic system installed.