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What You Will Do on Day 2
This field trip covers selected locations along the Blackstone River in south central Massachusetts from Worcester MA south to Narraganset Bay, RI. Images taken from the selected locations are included.
The purpose of this trip is to visit locations that exhibit typical uses of and associated impact upon the Blackstone River. Specific stops were selected based on readily seen examples that can be easily tied to broad concepts (e.g., eutrophication) while providing information on specific topics (e.g., wastewater treatment). This field trip, therefore, focuses on Massachusetts Audubon Society's Broad Meadow Brook Conservation Center and Wildlife Sanctuary, the Upper Blackstone Water Pollution Abatement District (the region's wastewater treatment facility), and Fisherville Mill, a superfund site typical of those along the Blackstone River.
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What You Will Need For Day 2
• Light-weight hiking boots (day hikers)
• Drinking Water, snacks
• Extra Socks
• Rain Gear
• Sun Block
• Insect Repellent
• Personal First Aid Kit
Fees (per person):
• $5 - Admission (Free for Members) to
MA Audubon Broad Meadow Brook
• $15 - Interpretive Tour at MA Audubon
Broad Meadow Brook
• $5 - $10 for lunch
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Field Trip
Massachusetts Audubon Society Broad Meadow Brook
Conservation Center & Wildlife Sanctuary
Stop #1
(~2 hours)
Broad Meadow Brook is one of the Massachusetts Audubon Society's 43 sanctuaries conserving some 30,000 acres of Massachusetts' ecologically significant land. The Broad Meadow Brook Conservation Center and Wildlife Sanctuary itself includes over 400 acres of forests, fields, marsh and waterway, and is one of the sub-watersheds of the Blackstone River.
IMAGE 1 - Broad Meadow Brook Lobby
Stephen C. Daukas, June, 2006
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The center offers excellent interpretive exhibits, a topographic scale model of the entire sanctuary, field guides, and reference materials. This facility is also one of the visitor's center for the National Park Service’s Blackstone River Valley National Heritage Corridor.
IMAGE 1 (left) shows the lobby's impressive hand-painted map of the Blackstone River Watershed and IMAGE 2 (below) enables the restroom facilities to become an interpretive exhibit in its own right as is allows restroom visitors to see how the plumbing is connected to the local wastewater treatment facility.
IMAGE 2 - Broad Meadow Brook Restroom
Stephen C. Daukas, June, 2006
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After becomming familiar with the Conservation Center, we will participate in an interpretive tour covering the different habitats of the watershed, noting soil types, flora and fauna, in the context of historical and present-day environmental stressors. These intrepretive tours are led by highly qualified Audubon Staff Instructors and are interactive by design. This tour is anticipated to take approximately 1½ hours. Upon completing the tour, we will wrap-up any questions and discussion at the visitor's center.
We will have lunch in the field and then continue to our next stop.
Blackstone River Valley
Upper Blackstone Water Pollution Abatement District
Stop #2
(~2 hours)
IMAGE 3 - Upper Blackstone Water Pollution Abatement District
Stephen C. Daukas, June, 2006
The Upper Blackstone Water Pollution Abatement District (UBWPAD) was created in 1968 by the Massachusetts General Court. Construction was completed, and the plant went on-line in 1976. The original design was to treat an average flow of 56 million gallons per day under the standards set in 1976. The UBWPAD is currently in the process of completing a $130 million plant improvement to help achieve the more stringent effluent standards of today and to accomodate storm-level flow through the plant that can exceed 75 million gallons per day.
A Tour of the Plant
IMAGE 4 - UBWPAD Plant
Stephen C. Daukas, June, 2006
IMAGE 5 - UBWPAD Inflow
Stephen C. Daukas, June, 2006
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Plant Overview
As previously noted, the plant is undergoing construction to allow the increase of its capacity to meet more stringent standards. This has afforded the opportunity to view some parts of the facility that would ordinarily not be visibile. some portions of the plant were not viewed so as to avoid active construction areas.
IMAGE 4 (left) is a view of the plant from the testing labs that overlook the facility. The inflow (Preliminary Treatment) to the plant is at the far left (outside the image) and leads to the Primary Treatment area (bottom of image). Some of the clarifier tanks that provide primary treatment are involved with the plant upgrade and are empty in the image. This portion of the process represents a low-energy environment that allows suspended loads to settle to the base of the tank, and also for less dense materials to float to the surface, where they are collected mechanically and processed seperately from that of the effluent. The Secondary Treatment system of the plant, where activated sludge is mixed with the effluent using aeration, is located just above the clarifiers. Excess sludge is also removed from the flow and pressed into cakes as part of the secondary treatment system. The final stages of the process are visible in IMAGE 3, a view of the "back" of the plant where final settling takes place (secondary treatment) and chlorine is added and removed from the flow (Disinfection) before being discharged into the Blackstone River.
IMAGE 5 (left) shows one of the inflow pipes to the plant. Until the plant upgrade began, this was the only inflow to the plant. An upstream distribution box has diverted the inflow into a new screening building. This portion of the plant also accepts effluent from private motor homes, as well as from commercial trucks hauling effluent from the pumping of private septic tanks.
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Preliminary Treatment
The initial processing involves a track of grates, which slowly rotates through the inflow stream, designed to trap items in the waste stream that might intefere with, or damage, the down-stream processes of the plant.
IMAGE 6 (below) is a view of the effluent flowing through the screening grates at the intake of the plant. The materials screened from the flow are carried up to the top of the unit where large pieces of debris are scraped off the grates (top left of IMAGE 6A) and fall down a shoot into a cart (bottom left of IMAGE 6A) where the material is removed for further processing. The remaining debris is ground to a uniform size (bottom-right of IMAGE 6A), where it moves up the pipe and is deposited into a rolling dumpster (IMAGE 6B).
IMAGE 6 - Screen/Grate at Inflow
Stephen C. Daukas, June, 2006
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IMAGE 6A (top) - Grinding Unit & IMAGE 6B (bottom) - Dumpster
Stephen C. Daukas, June, 2006
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The materials collected from this part of the process are burned with other de-watered solids from down-stream processes. The screened effluent continues on to the primary and secondary treatments facilities down-stream.
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The brick buildings shown in the background of IMAGE 7 (right) house the screening equipment. Not visible (due to construction) are the outdoor aerated grit chamber and the Parshall Flume where flow metering takes place. The grit chamber "freshens" the raw wastewater by bubbling air through it, which helps to separate the lighter organic material from the heavier "grit". The grit is removed from the process and landfilled without further processing as it is relatively free of organic matter. The image foreground shows where the two channels join to travel into the primary treatment area of the facility (the channel from the original screening building at left is not contributing to this flow as it is currently being upgraded). On the day of this tour, ~36,000,000 gallons of wastewater passed through the pictured channel. Although it is not evident from looking at the image, the current here is remarkably fast (estimated at greater than 15 mph).
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IMAGE 7 - Outflow from Preliminary Treatment
(Screening, Aerated Grit Chamber, & Parshall Flume)
Stephen C. Daukas, June, 2006
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When the upgrades to the plant are complete, the volume of inflow at this point could exceed 100,000,000 gallons per day. We now move from preliminary treatment to primary treatment.
Primary Treatment
Primary treatment removes approximately ½ of the suspended load, as well as approximately 30% of organic material, from the wastewater. IMAGE 8 and IMAGE 9 (below) show the clarifying tanks where the inflow is processed after preliminary treatment. Visible in IMAGE 9 (below right) is a red "pipe" that is part of the skimming system. This pipe is open on the opposite side and accepts the scum (grease, oil, etc.) from surface of the clarifier tank and pumps it to a sludge holding tank. A mechanical system at the bottom of the tank continuously collects the materials that settle out of the water column (primary sludge) and pumps this to the same sludge holding tank. IMAGE 8 shows the surface outflow from the primary tanks into a channel that leads to the aeration tanks (secondary treatment).
IMAGE 8 - Primary Outflow
Stephen C. Daukas, June, 2006
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IMAGE 9 - Primary Settling Tanks
Stephen C. Daukas, June, 2006
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Secondary Treatment & Disinfection
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The aeration part of the process functions to keep the water column uniformly mixed, as well as oxygenated, so that the bacteria and plankton can be more effective at removing pollutants from the wastewater. The wastewater remains in the aeration tanks for some number of hours to ensure complete processing. The length of time is on the order of several hours, but this is dependent upon inflow rates. Worcester's sanitary and storm systems are not completely seperate - heavy rainfall can greatly increase inflow to the plant. When heavy rains occur, residence time of the effluent in the facility is reduced, however the relative amount of effluent in the total flow rate is also reduced.
IMAGE 10 (right) shows one of the aeration tanks in operation. The mixing is continuous and is accomplished by a large fan (impellor) located the the bottom of the tank (IMAGE 11). In addition to this mixing action, tanks are fitted with aeration pipes along the bottom that operate in a similar fashion to that of aeration stones common in fish tanks (IMAGE 12 below).
 IMAGE 12, Aeration Tank
Stephen C. Daukas, June, 2006
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 IMAGE 10, Aeration Tank
Stephen C. Daukas, June, 2006
 IMAGE 11, Aeration Impellor.
Stephen C. Daukas, June, 2006
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The foam visible on the surface of IMAGE 12 (above) is a matt of living organisms. (A similar matt also accumulates in the corners of the aeration tanks with impellors.) This matt is thickest when the effluent contains a high concentration of fats and oils that this particular species of bacterium thrives on. The outflow from the aeration tanks is further processed in the final settling tanks (IMAGE 13 below) where the sludge from aeration settles. Much of this sludge is pumped back into the aeration tanks, while a smaller portion is removed and dewatered before being burned.
IMAGE 13 - Final Settling Tanks
Stephen C. Daukas, June, 2006
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IMAGE 14 - Chlorine Contact Tank
Stephen C. Daukas, June, 2006
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Wastewater moves from the final settling tanks shown in IMAGE 13 (above) to the final stage of the plant where chlorine is added to the wastewater (IMAGE 14 above) and detained in the chlorine contact tank until disinfected. Before the wastewater is discharged into the Blackstone River, the added chlorine is removed (inside the brick building) so that no interaction between the river water and wastewater takes place. IMAGE 15 (below) shows a water sample taken from the chlorine contact tank and IMAGE 16 shows the discharge from the plant into a concrete channel that leads to the Blackstone River.
IMAGE 15 - Water Sample
Stephen C. Daukas, June, 2006
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IMAGE 16 - Discharge From Plant
Stephen C. Daukas, June, 2006
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Solids Processing
Sludge from primary and secondary treatment, and scum from primary treatment, is dewatered and formed into cakes. The cakes are burned in an on-site multiple hearth furnace (IMAGE 17) that produces an inert ash (IMAGE 18) that is landfilled on-site (IMAGE 19 background). Heat generated from the incinerator is used to heat the buildings.
IMAGE 17 - Furnace
Stephen C. Daukas, June, 2006
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IMAGE 18 - Inert Ash
Stephen C. Daukas, June, 2006
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IMAGE 19 - Landfill
Stephen C. Daukas, June, 2006
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We will now depart for Fisherville Mill in Grafton, MA, our next stop on this leg of the field trip. Turn left out of parking area onto Route 20 East. Continue for ~????? miles to ?????.
Fishervill Mill
Stop #3
(~2 hours)
IMAGE 20 - Fisherville
Stephen C. Daukas, June, 2006
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As previously mentioned, Fisherville Mill is representative of the many former industrial manufacturing sites along the Blackstone. This mill is located in Grafton (known as South Grafton to local residents) Massachusetts on Main Street (MA Route 122A). This area is part of the National Park Service's Blackstone River Valley National Heritage Corridor, a 400,000 acre region in central Massachusetts and northern Rhode Island. The Corridor Commission maintains the official home page for the parks and centers in the Corridor.
Our visit to the site requires permission from the current owners, Cover Technologies, Inc. Care must be taken while moving about the site as additional remediation (pump & treat) is about to begin, and heavy construction equipment is activly clearing debris in preparation for future construction. Also, be mindful of where you step taking care to not walk on any wiring, cables, tubing, unstable rubble, or sharp objects (rebar, etc.).
A tour of the site will use the pictures provided by the EPA supplimented by those taken during several site visits during June and July of 2006.
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FIGURE 1 - Fisherville Mill
From: USAF CEE / USN FESC 2004 publication (see references)
IMAGE 21 - Fisherville Mill
Stephen C. Daukas, June, 2006, Using: 2001 MassGIS Orthophoto Database (Oliver)
FIGURE 1 (above top) shows a site plan prior to the 1999 fire, and IMAGE 21 (above) is an orthophoto generated using Massachusetts' MassGIS system based on 2001 data. The foundation of the mill, all that remains after the 1999 fire, is visible in IMAGE 21. By examing IMAGE 21, one can see that the property is bounded on all sides by water. North (right) of the foundation in IMAGE 21, immediately proximate to the mill, is a channel that joins the Blackstone Canal to the Blackstone River. To the north (right edge of image) is Fisherville Pond (partially drained). The property is bordered by the Blackstone River to the East (bottom of image), the Blackstone Canal to the West (top of image), and Fisherville Pond to the North (right of image). MA Route 122A (Main Street) crosses the site (top to bottom). The Worcester & Providence Rail Road tracks roughly parallel the canal at the top of IMAGE 21.
The site is contaminated with heavy metals, asbestos, solvents including volatile organic compounds (VOCs), and petroleum products. The Massachusetts Department of Environmental Protection was maintaining a groundwater treatment system to remediate the contaminated groundwater until the Mill and the MA-DEP's equipment was destroyed by a suspected arsonist's fire in 1999. The Commonwealth and EPA responded to mitigate the impact of the asbestos involved in the fire, and to reestablish monitoring and remediation at the site. 3,400 tons of contaminated surface debris was removed from the site, as was over 3,000 tons of building debris, PCB-contaminated oil and transformer cases.
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There are now 35 monitoring wells located at the Fisherville Mill site with sampling showing a presence of 12 VOC contaminants. Sampling from multiple wells show a VOC (TCE) groundwater plume moving through the overburden. This plume originates at the western edge of the former mill and moves generally south into the Blackstone River (discharging from the eastern edge of the peninsula formed between the river and the canal).
The Blackstone Canal's current water level (FIGURE 1, IMAGE 21 & 22) must be maintained to ensure a sufficient hydraulic gradient to prevent the groundwater plume from moving towards the residential area to the west. IMAGE 22 (right) shows the temporary dam impounding water behind it.
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IMAGE 22 - Dam Maintaining Water Level
From: EPA Fisherville Mill Site Profile, 2004
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Monitoring Groundwater
In 2002, the EPA installed a ground water treatment system to replace the Mass. Department of Environmental Protection (MA DEP) system destroyed during the 1999 fire. Over 100 wells have been used to inject sodium permanganate into the trichloroethylene (TCE) contaminated ground to covert the pollutant into harmless substances (inorganic salts). TCE is a colorless solvent known to cause cancer and affect the imune and nervous system of humans. Direct exposure by contact or inhalation (unlikely at this location) to high-concentrations of TCE can cause death.
IMAGE 23, 24, 25, and 26 (below) show several monitoring / injection locations, as well as ths in situ oxidation treatment facility and pumping station, located in and around the former mill structure. The site is being monitored by MA DEP to ensure TCE levels do not "rebound". Remediation to date has cost several million dollars, inclusive the of $500,000 emergency clean-up after the 1999 fire.
[Click Image to Enlarge]
IMAGE 23 - Injection Site ('03)
From: EPA Fisherville Mill Site Profile
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[Click Image to Enlarge]
IMAGE 24 - TCE Oxydation ('04)
From: EPA Fisherville Mill Site Profile
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[Click Image to Enlarge]
IMAGE 25 - Turbidity Testing ('04)
From: EPA Fisherville Mill Site Profile
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[Click Image to Enlarge]
IMAGE 26 - Pump System ('04)
From: EPA Fisherville Mill Site Profile
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From Main Street (MA Rt. 122A), access to several monitoring wells to the south is unrestricted and adjacent to the unpaved parking area (see FIGURE 1, "Pilot Test Area"). IMAGE 27 and IMAGE 28 (below left) show two typical wells still actively being used to monitor the site (notice the padlock visible in IMAGE 27). IMAGE 29 and IMAGE 30 (below right) show the former mill building location.
[Click Image to Enlarge]
IMAGE 27 - EPA / MADEP Well
Stephen C. Daukas, June, 2006
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[Click Image to Enlarge]
IMAGE 28 - EPA / MADEP Well
Stephen C. Daukas, June, 2006
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[Click Image to Enlarge]
IMAGE 29 - For Mill Site
Stephen C. Daukas, June, 2006
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[Click Image to Enlarge]
IMAGE 30 - Debris Pile
Stephen C. Daukas, June, 2006
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Visible in IMAGE 29 (above) is a rubble pile of brick and foundation material, with an outbuilding of the 1832 structure visible to the right of the second storage tower. IMAGE 30 shows the pile of debris collected from this portion of the site.
Return to the rest area for departure to hotel.
This completes our tour of the area for the day.
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