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!

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

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).

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

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

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

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.

Why do you need to hire a Professional Civil Engineer to design a Septic System?

How many times have I heard, “The man who pumps-out my tank said he uses a guy who can do the design for him directly and he can give me a design & construction deal that will save me money.” Does this sound too good to be true?  Have you ever heard the quote, “There’s a sucker born every minute“? (P.T. Barnum or David Hannum, you decide who said it first, but as a Tufts U. graduate, I vote for Barnum)

Everyone wants to save money. A recent “Close to Home Cartoon by John McPherson caught my attention.

When it comes to a failed Septic System, you need to get professional help.

While the man who runs the pumping truck has working experience regarding the “contents” of a septic tank, unless he is a Registered Sanitarian or a Civil Engineer, he is not qualified to prepare a septic system repair design in most States.

A qualified professional will be able to provide you with design alternatives and assist you in the selection of an installation contractor when you get price quotes based on the design plans. A qualified professional will work directly for you, not work for or be paid by the contractor (Does the phrase, “conflict of interest” mean anything?)

Please download this Free Pamphlet – “Valuable Information on Title 5 Septic System Perc. Testing,
Soil Evaluation & Design Engineering” by Michael E. Perrault, P.E.

This pamphlet was specifically designed as a checklist to assist you, as a property owner, in the steps needed to have a replacement septic system designed, etc.

What a long cold winter! The snow is finally melting and I can actually see some lawns.

How do you know that Spring is near?   The Red Sox are in Ft. Myers?   The St. Patrick’s Day decorations are available in CVS & Walgreens? The pot-holes in the street in front of your house resemble the Grand Canyon?

I know that Spring is near when septic system contractors start constructing replacement septic systems. All those designs that were completed before the ice-age hit last December became “shovel ready” over Winter. Homeowners living with a failed septic system just want to get it fixed so the yard will be normal come Summer. The same applies for those people trying to sell their homes. They want to get the new septic system installed and the yard restored thereby eliminating last minute construction before the closing.

Just this week construction started on one of our septic system repair design projects. The septic installer coordinated the construction with our office and the Board of Health to confirm that we would be available to perform the multiple construction phase tasks. For example, once the excavation is completed, the design engineer has to visit the construction site to observe and confirm that the unsuitable soils have been removed and that the excavated hole is ready to be backfilled with sand. The Health Agent also performs his own observations as the work progresses. The contractor had already installed the new 1,500 gallon septic tank and 1,000 gallon pump chamber in order to provide a temporary holding storage while the replacement system was being constructed.

Once the sand had been placed, the septic contractor installed the leaching chambers, distribution box and connecting pipes. Since this system will use gravity flow from the distribution box with a pump chamber to lift the septic tank effluent to the distribution box elevation, the distribution box and the chambers are designed with vent pipes. To help reduce the overall construction cost, our design used a chamber system that does not require any washed stone according to the State approval documents. The completed leaching area is also covered by a geotextile filter fabric. The State Sanitary Code requires the design engineer to observe this construction, make sufficient measurements to confirm that the components were properly installed and then prepare a plan showing the constructed system (This is called the “as-built” plan). The as-built plan is submitted to the Board of Health with a letter signed by the professional engineer, which states that the system has been installed in accordance with the approved plan.

Now that I have proof that Spring is near, what proof do you need?

How about some good news?  The cost of replacing a failed septic system is low. The slow down in construction has increased competition and reduced the costs. So now may be the best time to get that failed septic system replaced.

Is there bad news? Yes, be sure to investigate the qualifications and reputation of the “lowest price” contractor and carefully read the contract for items that are not included.

It may be human nature to want to get something for nothing. Free samples. Free trial services. Free membership. Buy one, get one free.

With tough economic times, why not try to get something for free or a a great discount? Comparison shopping is becoming the rule and not the exception. There is nothing wrong with this.

What about free engineering or discounts for engineering services? Does the consumer really get a discount or engineering services for free? A favorite author of mine used the acronym “TNSTASFL” (There is no such thing as a free lunch). I am a firm believer that when it comes to professional engineering services, there is no such thing as free engineering services.

For example, a potential client will call to request a proposal to provide engineering design services for a replacement septic system. During this call, we listen to his request, ask specific questions to gain a better understanding of his needs, answer his questions and based on his request and generally describe the professional engineering services that we offer. We then follow-up with a detailed written proposal outlining our services and associated costs that are specific to the potential client’s property and situation.

Since this process of engineering and replacing a failed septic system can be overwhelming, we contact the potential client to discuss the proposal and answer any questions.

This is where the concept of free or discounted engineering services enters.  The potential client has a family member or friend that told him that our prices are too high and he knows a guy that will “do it” at 2/3 of the price, or some other low number.

Are the services being provide by the “guy” the same? Are they clearly spelled out in a written contract?

What I have found, when I have lost a client to the “guy” with the discounted price, is that he did not include the construction phase services and had to charge extra. The “guy” never returns a telephone call or is hard to contact. The “guy” takes “forever” to complete the design. In some instances, the “guy”, in order to reduce his costs, he provided the client with a standard minimal design, even though it may not be suitable for the individual property.

To perform services at a reduced cost, the amount of time being spent has to be reduced (no one works for free). When this happens, the quality of the design is compromised. The reviewing authority may question the design and require revisions prior to approval (careful, these revisions may be charged back as an extra). While the basics are provided on the design plan, the details, specific to a client’s property may not be clearly shown.

Maybe the “guy” has reduced overhead costs and can pass these savings onto his clients. For example, the “guy” may not have any Professional Liability Insurance or General Liability Insurance.

So the client now gets a set of plans at a discounted price, then asks several contractors for a bid price for the installation. While contractors know the costs for installation of various components, each design for an individual property needs to be reviewed and priced. When the plans are vague and the details are not really or clearly presented, the contractor will need to include extra costs in his bid. A complete set of plans that are well presented will minimize the need for a contractor to include a large contingency in his bid.

What was “saved” on the design plans can easily be spent during construction. So much for a discount.

There is noting wrong with comparison shopping among qualified engineering consultants. The consumer however, may not find out until it is too late, that the discounted price actually cost him more.

By Michael E. Perrault, P.E.

When does a septic system design need to include a pressure distribution leaching system? Prior to the 1995 changes to the Massachusetts Sanitary Code (310CMR 15.00), a pressure distribution system design was not required. The 1995 Code revision did not have any actual design criteria except for a requirement to utilize a pressure distribution system when certain thresholds were reached. The actual design methods were contained in a Department of Environmental Protection (DEP) policy document . This “policy” called Title 5 Pressure Distribution Design Guidance, has been further revised to address the technical questions that were raised by the original policy (Policy#BRP/DWM/WpeP/G02-2, effective May 24, 2002). The more recent revision to the Sanitary Code appears to have added more confusion.

My office recently prepared a septic system repair design for a small manufacturing facility located in an industrial park. The total facility design flow was less than 2,000 gallons per day (GPD). The proposed design included a gravity style distribution to the leaching system, but needed a pump system to bring the flow from the septic tank to the gravity distribution system.

The local health agent reviewing the design plan was of the opinion that the design needed to use a pressure distribution system. Unlike a conventional gravity style system, a pressure distribution system uses a force main pipe from the pump chamber to a larger diameter manifold pipe (can be a central manifold or an end manifold). A series of smaller lateral pipes are fed from the manifold pipe. These lateral pipes have a series of small diameter holes spaced along the length of the lateral pipe. These holes in the lateral pipes thereby spray the pumped effluent under pressure into the leaching system. Pressure distribution systems are more expensive to install as compared to the conventional gravity systems.

When the health agent first questioned the design, I explained that the Sanitary Code, under 310CMR15.254(1) allowed for dosing pumps for systems with a total design flow less than 2,000 GPD provided that there is a gravity distribution system. The health agent did not agree with my reading of the Code and contacted the regional office of the DEP to get an “official” opinion. The DEP engineer actually sent a fax that stated that all pumped systems had to be pressure dosed and attached the section of the Code related to pressuring distribution (310CMR15.254(2)). Once I was given a copy of this DEP fax document, I contacted the same engineer at the DEP and suggested that he not skip to the second paragraph in the Code section 15.254 that he cited, but start at the first item that clearly allows for pump dosing to a gravity distribution system for design flows under 2,000 GPD.

I explained that pressure distribution systems, while an option, are not typically used on small systems. For example, if an existing small single family house, under a repair design, needed to have a slightly elevated leaching system due to high groundwater, and the plumbing location prohibited a total gravity system, then, under the “all systems using a pump” opinion, this property would be forced to have a pressure distribution leaching system.

I then went through the appropriate Code section wording with the DEP engineer and discussed the differences between the two paragraphs. The DEP engineer then issued a new fax to the health agent correcting the earlier fax and noting that the pumped system design was allowed and that “pumped” systems without pressure distribution is acceptable provided that they meet the Code criteria.

At that point, the health agent, under the authority of the Board of Health, approved the design plan and issued the construction permit.

If I had not insisted that the DEP engineer had been incorrect, my client would have had to pay for an expensive pressure distribution system.

An engineer who does not have a good working knowledge of the Massachusetts Sanitary Code as well as the experience in both pump dosing and pressure distribution system design would not have questioned the health agent’s opinion and definitely would not question a DEP engineer.

There is no substitution for experience.

I recently heard about an example of how experience impacted a pressure distribution system project. A local contractor, was installing a pressure distribution system (not one of my designs, thank you) when the local health agent had him tear out the manifold and lateral connections. The design plan, according to my source, did not detail how these connections were to have been made and the contractor built what he thought was correct. A more experienced design engineer would have had that detail presented on his plan, since that piping connection is one of the more critical components of the pressure distribution system. This lack of detail not only resulted in more work and expense for the contractor but delayed the completion of the system construction.

This is one of my typical pressure distribution system design details.

Clients do not appreciate an engineer gaining on-the-job training on their projects.

While there are some people that base their decision to hire an engineer on the lowest price, the smart consumer looks at experience, reputation and integrity in combination with the cost to establish the “value” of a project.