Introduction

         The customer for this year's project is the City of Newton, Massachusetts.  The Mayor, David B. Cohen, and Jay J. Fink, Utilities Director, and Theodore J. Jerdee, Utilities Superintendent of the Water and Sewer Division are the sponsors of the project, and they are the part of the group to whom your final report and presentation should be directed.  Our sponsors and all of the citizens of Newton are interested in cost effective improvements in the wastewater sewer systems of the City.  The class project is to discover weaknesses in the present complex wastewater systems which can be improved in a cost effective manner while meeting the objectives of the sewer system.

        Some of the very  important functions of every city and town in an urban area are:

• to provide a clean healthful water supply to each home, school, office building and factory;
• to provide for the collecting of waste water from storm drains in the streets and the collection of excess ground water;
• and to provide for the safe and sanitary collection of sewage from homes, schools, office buildings and factories.

         In urban areas, the cities and towns are individually responsible for the distribution of drinking water and the appropriate collection of waste streams within their communities.  Drinking water is generally delivered to the municipalities by a regional water authority, and the sewage waste streams are generally treated in a central treatment plant.  In the Boston metropolitan area these two functions are combined in a single independent state agency, the MWRA - the Massachusetts Water Resources Authority.

        The Massachusetts Legislature created the MWRA in 1985 to manage water and sewer services for 2.5 million people and 5,500 businesses in 61 communities.  While the Boston Harbor Project is the best known of MWRA's projects, the Authority also maintains 400 miles of water pipes, aqueducts and tunnels, and 228 miles of sewers.  Also underway are projects to control combined sewer outflows, provide adequate water delivery and meet all federal, state and local water and sewer standards.  The MWRA supplies drinking water to almost all of the communities of greater Boston, and it collects and provides primary and secondary treatment of the sanitary wastes from these communities.  In the past decade the MWRA has directed a multibillion dollar construction program to provide for a state-of-the-art treatment plant in Boston harbor and to upgrade the main line drinking water delivery system from the Quabbin Reservoir in western Massachusetts.

         The history of what is now the Commonwealth of Massachusetts dates from early in the 17th century, when the area consisted of separate widely scattered clusters of settlements.  What the local newspapers call the Republic of Cambridge was one of the earliest settlements and was always separate from Boston and most of the rest of the metropolitan area.  This independence led Cambridge in the 19th century to establish  it own Water Board (Professor Harrington is President of this Board), with its own reservoir to supply the City with drinking water, though Cambridge uses the MWRA treatment plant to process the city's sanitary wastes.  As you might imagine, all possible combinations of local supply and treatment exist in the metropolitan area with each city and town free to decide what to do provided it satisfies state regulations and federal standards for drinking water and waste water discharge.
 

Instructors

Frederick H. Abernathy;  Pierce 326; 617-495-4709; fha@stokes.harvard.edu
Joseph J. Harrington; Pierce 113; 617-495-2859; harringt@fas.harvard.edu
Teaching Fellow; Radhika DeSilva; 119 Pierce Hall; 617-495-7620; rdesilva@fas.harvard.edu

Students

Class Meetings

Monday 2-4pm and Thursday 2-4pm.
The Thursday meetings will also be used for separate task group meetings.
Students in the ES 96 must not make other commitments which conflict with these hours.

Field Trips

Several field trips are part of the course and they will be  scheduled, where possible, during the regular class meeting times.

 GENERAL DESCRIPTION OF STUDY AREA

The City of Newton lies entirely within the Charles River Basin (Figure 1, Figure 2).  As you will notice from the maps of the drainage basin, the Charles River flows in a very complex path from its head waters to the sea.  The Charles River drains rain and ground water from the communities within its basin.  As you may have noticed after very heavy rains the Charles River, which flow through the Harvard Campus, is contaminated with sanitary wastes due to combined sewer overflows from communities upstream and occasionally from Cambridge and Boston.   The communities in the Charles River basin and the MWRA are trying to reduce if not eliminate such contamination from the Charles.  Newton is one of those upstream communities trying to eliminate such contamination.  The Charles River Watershed Association is an important community organization which has focused on all aspects of reducing  pollution in the entire Charles River watershed, and on maintaining streamflow in the river in the dry summer months.  Their web site reports levels of bacteria (fecal coliform) for each measuring site along the flow of the river.  Bacteria levels are measured by counting colony-forming units of fecal coliform per 100 milliliters (about a teacup of water.)

The City of Newton and Its Sewer System 1

"The City of Newton is located in Middlesex County, about ten miles west of downtown Boston.  The city is bordered by Waltham and Watertown to the north, Brighton and Brookline to the east, West Roxbury and Needham to the south, and Wellesley and Weston to the west.   Half of the city''s border is formed by the Charles River.  The city is primarily residential, with several industrial plants, some commercial establishments and a few educational institutions.

"Rapid growth in Newton began prior to 1900 and the city grew as one of the earlier suburbs of the downtown Boston area.  According to the Massachusetts Metropolitan Area Planning Council, the city's population in 1980 was 89,800.  Today the city is fairly well developed and no major increases in population are expected in the future. "

The following paragraph is general information from the cited report.  It is useful to know generally which sections of the City fall into which sewer area.  A small (8 1/2x11inch ) version of the referenced figures will be distributed in class.

"During the Facilities Plan Study and Sewer System Evaluation Survey Study   (a report of the City of Newton), the City's sewer system had been divided into three collection areas which have been designated as Areas A, B, and C.  (Ref. Figure I-1; ... see referenced report under 1 above).  Area A is located in the southwestern portion of the city.  Area B encompasses the remaining northern two thirds of the city.  Area C is a small area in the southeastern corner of the city.  For purposes of analysis, these three areas have been further subdivided into a total of 100 smaller areas called mini-systems and are shown on Figure I-1.  The segments of interceptors which collect wastewater from these 100 mini-systems are shown in Figure I-2 (see referenced report  1 above).  Also shown in Figure I-2 are the locations of the seven sewage pumping stations which are owned and operated by the City of Newton.  The purpose of this study is to evaluate a small area, Minisystem B45, which is known to have a combined underdrain and sewer system, and to use this as a test program before undertaking a program in the remaining system.  If rehabilitation methods are found to be effective in this one minisystem, then similar methods can be utilized in evaluating the underdrain and sewer system throughout the remainder of the city."

The following paragraph is a general description of the Newton sewer system.  Again it is quoted from Reference 1

 "The existing sewer system contains approximately 1,397,200 linear feet (264.6 miles) of sanitary sewers and 7,900 manholes.  The greatest part of the sewer network is made of smaller diameter vitrified clay pipe.  There are also reinforced concrete sewers with diameters ranging from 6 inches to 66 inches and egg-shaped brick sewers with dimensions of 24 x 36 inches and 20 x 30 inches.  Depths of sewers range from about 6 feet to 25 feet.  All but a few manholes are made of brick.  The majority of sewers were built prior to the development and use of rubber gaskets for waterproofing joints of pipes and manholes.  The oldest sections of sewer are located in the northern part of the city (Area B) and were built during the 1890s and early 1900s.  Most of the sewers in the southern part of the city (Areas A & C) have been built during the past 50 years.  The existing sewers in Area B are primarily vitrified clay pipe with brick manholes.  The majority of sewers were constructed without sealing gaskets to maintain waterproof joints.

 "Some of the older sewers were constructed with a network of underdrains beneath the sewer.  It is estimated in the Facilities Plan that approximately 430,000 linear feet of sewer was constructed with an underdrain system.  The underdrain pipes range in size from 4 inches to 18 inches in diameter.  During the I/I study, pre-selected manholes which were thought to best give an overall synopsis of the sewer system were physically inspected.  There was a frequent observance of underdrain access points in these manholes.  This underdrain system has a two-fold purpose.  It was originally thought to be designed to dewater the trench to facilitate the construction of the sewer.  Where sewers were constructed at elevations higher than nearby streams, underdrains were typically diverted to those streams.  Reportedly, many of these diversions have been plugged because the underdrain flow was contaminating the streams.  In some instances, the inflow from the underdrain system now backs up and overflows into the gravity sewer and contributes to the surcharging of sewers.  More importantly, it was recently discovered that the underdrains were installed for the purpose of lowering ground water throughout an entire area.  This made the land a more valuable commodity and more attractive to builders."

The Underdrain System

In class the full text of the Childs' article will be distributed.  The description below is from Reference 1.

"The underdrain system was originally designed to lower the water table to make real estate development more feasible.  It was also used to temporarily dewater the construction trench to facilitate the construction of the sewers.  Access openings to these underdrains were constructed through the inverts of many of the sewer manholes to allow for flushing of the underdrains.  In areas where the quantity of wastewater currently exceeds the capacity of the sewer, sewage has been observed overflowing into the underdrains through these openings thus acting as relief sewers.  At several other locations, large volumes of flow can also be seen overflowing from the underdrains at these access openings into the sewer.  This situation is due to either failure or a blockage of a downstream section of the underdrain.  The points of discharge of the underdrain flow are not always clearly indicated.  When the elevation of the underdrains was higher than a nearby drainage channel, the underdrain flow was apparently routed to these outlets and away from the trench of the sanitary sewer at the time of their construction.

"Figure II-3 shows a detail of an underdrain as indicated on the cityís sewer plans.  The underdrains in Newton were constructed with open joints and surrounded by coarse granular material (Childs, 2).  Because of this surrounding material it would be difficult to effectively seal these underdrains.  In fact, to cut off the flow of ground water, it might be necessary to construct a clay cut off dam at regular intervals along the route of the underdrain."

•             Water consumption and sewer billing for the City for the past several years.

•              Costs to the City for MWRA water and sewer.
•              City's annual cost for water and sewer maintenance.
•              Record of daily rainfall in Newton.

There will be two major projects for the class.   The class will form two working groups.  Group 1 should have 3 or 4 students and Group 2 will have 7 or 8 students.  The groups will share basic information and ideas.   Each group will make a weekly presentation of what they are doing and what are the task they are working on.

Working Group 1

The main sewer line in Newton Upper Falls (UF) discharges through a pump station into a main MWRA gravity-flow large diameter (several feet) sewer.  This sewer was at one time the Cochituate aqueduct.  The Cochituate sewer flowing from Wellesley is combined with the output of the Quinobequin Road pump station.  When the Cochituate sewer and reaches its capacity, the overflow bypasses the Cochituate sewer and drops down through a bypass to the Auburndale section of Newton.  The Auburndale area is connected to a different main MWRA sewer.  When the maximum capacity of the Auburndale section of the sewer system is reached, the overflow discharges into the Charles River at Lyons Playground.  The overflow of the Auburndale sewer causes a major environmental event.  The untreated sewerage flows over a children's playground, a portion of a Little League ball field, and blocks access to a riverside park as it flow over the ground to the nearby Charles River.

 Major sewer overflows at Lyons Field has occurred three or four time in the last decade.  The sewer outflow has continued for up to four days closing the fields for several weeks.  The City has then removed contaminated topsoil, spread lime, grass seed and allowed sunlight to disinfect the parks before allowing public use.  Clearly a major problem for the City and for the users of the Auburndale recreational parks.

 There are a number of ways that the capacity of the Cochituate Sewer might be increased.  An engineering study needs to be undertaken to determine if any of the possible approaches might be a cost efficient way to solve the problem.

This  project is to study this mini-sewer system, explore a number of possible solutions, cost out the possibilities and make a recommendation.  Instrumentation for the flow system might be built and installed in the actual sewer system as a part of this design and build task.

This project treats the Newton Corner Mini-system Test area. The general picture of the drainage of wastewater from Newton has been described above. We quote from Reference 1: "The City of Newton is undertaking to upgrade its wastewater collection system so as to eliminate excessive [sic] inflow/infiltration to its sewer system which can create public health hazards within the city."

It is the case that the City buys from the wholesaler (MWRA), and sells to the public as retailer, about 10 million gallons of water per day (mgd) which is substantially less than the amount of wastewater, as much as 24 mgd, that it must pay the MWRA to handle. Of course, the City bills the citizens to cover these costs.

Taking into consideration the size of the class, we asked our partners in Newton to select a representative section of the city that had several of the problems that we knew about, including drains, underdrains, sanitary sewers and interconnections. The cited reports by Woodard and Curran Inc. detail an investigation into sources of non-stormwater pollutants into USEPA identified storm drains.

It is the purpose of this task to provide an engineered approach to alleviating this set of problems. The sub-tasks outlined below are suggestions of some elements that might be considered. They are not intended to be an outline of the solution that the design group will finally recommend to the client.

Sub-task 1: A map of the selected mini-system is due from Newton (Ted Jerdee). This is expected to be in GIS (Newton) format.

Sub-task 2: The Second Edition (1998) of Computer Applications in Hydraulic Engineering - Haestad Methods has been received and the software will be will be loaded by Friday, February 19. In particular, StormCAD may be useful for exploring design options later in the project. One important component will be to identify possible interfaces between it and the GIS database.

Sub-task 3: Quantification of Inflow/Infiltration

1. Past studies have used fluoride as a tracer for the sanitary sewage component of the wastewater flow, since the MWRA routinely adds it in the concentration of 1 mg/l.
2. Ion-specific electrodes for fluoride are available (see USA Blue Book Wastewater and Water Buying Guide, pp. 70 ff. [Cruft 114]).

 

 
 
 
 
 
 
 
 
 

Notes: the sensitivity of the cited instruments may not be sufficient when the flow is substantially diluted by inflow/infiltration. Tim MacDonald of the Cambridge Water Department (see that website) has expressed a willingness to share some of his experience.

3. Other chemical compounds in the non-sanitary wastewater could be considered. Determine what data are available.

Summary of Talks and Meetings

Guest Speaker : Dr. William C. Pisano, Ph.D., P.E. received his B.C.E. from Santa Clara University, M.S. from University of Arizona, and his Ph. D. from DEAS with Professor Harrington in 1973. He currently is a Vice President of Montgomery Watson, a large environmental engineering consulting firm.

His specialty is combined sewer overflow (CSO) technology. He is currently Project Director for Design of Floatables Control, Sewer Separation and Storm Water Management, Cambridge, MA.

Dr. Pisano will talk about Management of Sewer Flows.  February 11, at 2:00 pm.

Two copies of his report, "Sewer and Tank Sediment Flushing: Case Studies", sponsored by USEPA, October 1998, are now on reserve at Gordon McKay library. Chapter 7 includes a brief "desktop analysis" of the project that he described at Fresh Pond Parkway Sewer Separation and Surface Enhancement Project Storm and Sanitary Sewer Flushing.

References:

1. Report on the Underdrain Test Program in Minisystem B45  in Newton, Massachusetts; July,1990; Coffin & Richardson, Project No. 1966; pages I-2, I-7.

1. Childs, Stephen; Maintenance of the System of Separate Sewers at Newton, Mass, Journal of the Association of Engineering Societies, Vol. XXII, January to June, 1899, Pages 94-111