Facts & Figures
To gain some idea how dominant the effluent flow of the Brockton Waste Water Treatment Plant is in the upper Taunton River we have provided the figures below. The plant according to (CDM, the cities engineering firm) discharges an average of 21.5 million gallons of effluent per day into the Salisbury Plain River. We will use a figure of 20 million gallons per day (MGD) for our purposes because the flow does fluctuate, and sometimes goes down to 17 or 18 MGD.
{NOTE} The Salisbury Plain drains into the Matfield River which in turn joins the Town River to become the Taunton River above Rt. 104 in Bridgewater. It is important to note that during low summertime flows (below 100cfs at Titicut St) the Salisbury Plain and Matfield Rivers are little more than sluiceways filled with effluent from the Brockton Sewer Treatment Plant. During these low flows there is very little water coming into these streams to buffer or dilute the effluent. In fact it would not be inaccurate to say that when flows are less than 100 cfs at Titicut St, the Matfield, where it joins with the Town River to form the Taunton River is so dominated by effluent that it, for all practical purposes becomes the direct discharge point for the Brockton Sewer Treatment Plant.
{NOTE 1} The 7Q10 at the Titicut St gauging station is 24.6 cfs according to Ma DEP. At this flow the Upper Taunton River would be little more than a river of effluent.
What is the 7Q10? (Courtesy of Ma Riverways)
The 7Q10 refers to the lowest consecutive 7 day streamflow that is likely to occur in a ten year period. It is used by many states and the federal government in setting discharge limits in National Pollutant Discharge Elimination System (NPDES) water quality permits. A permit will only be granted if the proposed amount of pollutant that will be discharged into a river will not significantly impair the designated uses, such as drinking or swimming, when the streamflow falls to the 7Q10 level. In other words, NPDES permit holders are restricted from discharging pollutants that would cause pollutant concentrations in the receiving water to exceed permit limits, even at very low (i.e. 7Q10) streamflow levels. Although such a low streamflow value, roughly equivalent to a ten-year drought, is appropriately used in the context of limiting pollution discharges, the 7Q10 flow statistic is sometimes inappropriately claimed to represent an adequate streamflow for maintaining a healthy aquatic ecosystem, when in fact much higher streamflow levels are required.
We have used the 7Q10 figures for these tributary streams which were calculated by the United States Geological Survey to demonstrate how dominant the Brockton Sewer Plant is in the Salisbury Plain, Matfield and Upper Taunton River.
The 7Q10 flow above the Brockton Sewer Treatment Plant on the Salisbury Plain River is 0.6 cfs or 927 thousand gallons of water per day (to convert cfs to gallons per day you divide .647 the conversion factor by 0.6). Therefore at the outfall of the plant the mix is 20 million gallons effluent to 927 thousand gallons river water.
The next significant downstream tributary is Beaver Brook. At the confluence of Beaver Brook and the Salisbury Plain River the Matfield begins. Beaver Brooks 7Q10 flow is .3 cfs or 463 thousand gallons per day. Therefore where the Matfield begins the water to effluent ratio is 1.4 mgd (million gallons per day) river water to 20 mgd effluent.
The next significant downstream tributary to the Matfield is Satucket River which is below Rt. 18 in East Bridgewater. Satuckets 7Q10 flow is 1.3 cfs or 2mgd. Therefore at Satucket the ratio of river water to effluent is 3.4 mgd river water to 20 mgd effluent.
Below here approximately 8 miles below the Brockton Sewer Plant the Matfield River meets the Town River above Rt. 104 in Bridgewater to become the Taunton River. The Town River 7Q10 flow is 2.7 cfs or 4.1 mgd. Therefore where the Taunton River begins the ratio of river water to effluent is 7.4 mgd river water to 20 million mgd effluent.
While this is a simplified example of the dilution or lack of dilution, it is instructive and provides a good example of how dominant the effluent flow of the Brockton Sewer Plant is in the Taunton, Matfield and Salisbury Plain Rivers.
It's also worth noting that these 7Q10 figures for the tributaries were calculated in the 1950's and 1960's when water demands were much lower than they are today. In a study performed on the Matfield watershed in the summer of 2002 Beaver Brooks flow was recorded as 0 on one sampling day.
As examples we can look at the Nemasket River and the Middleboro Sewer Plant. the Middleboro plant discharges approximately 1.3 mgd of effluent into the Nemasket River. Nemasket's 7Q10 flow is 4.2 cfs or 6.5 mgd. Therefore the Nemasket at the plants discharge point has a ratio of 1.3 mgd effluent to 6.5 mgd river water.
Another good example is the Town River in Bridgewater. Bridgewater's plant discharges about 700 thousand gallons per day into the Town River. The Town River's 7Q10 is 2.7 cfs or 4.1 mgd. Therefore the Town River has a ratio at the plants discharge point of 4.1 mgd river water to 700 thousand gallons per day of effluent.
The table below shows flow figures at Titicut St. for the summer of 2002.
Glossary of commonly used terms (courtesy of Ma Riverways)
The following link provides a series of photo's showing the difference in flows of the Matfield and Town Rivers.
We provide a link to this site in our good eggs section on our home page, it's a great resource.
USGS 01108000 TAUNTON RIVER NEAR BRIDGEWATER, MA
PROVISIONAL DATA SUBJECT TO REVISION |
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The following is from the EPA ECHO ( Environment and Compliance History on Line) website. It lists the permit violations that have taken place at the Brockton plant in the past two years. Below this table is a detailed description of how to interpret the figures provided.
| CWA/NPDES Compliance Status | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
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Statute:Source ID CWA:MA0101010 |
|
QTR1 Jul-Sep00 |
QTR2 Oct-Dec00 |
QTR3 Jan-Mar01 |
QTR4 Apr-Jun01 |
QTR5 Jul-Sep01 |
QTR6 Oct-Dec01 |
QTR7 Jan-Mar02 |
QTR8 Apr-Jun02 |
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| Facility Level Status » | E(EffViol) | E(EffViol) | E(EffViol) | E(EffViol) | E(EffViol) | E(EffViol) | E(EffViol) | E(EffViol) | ||
| Effluent Violations by NPDES Parameter: | ||||||||||
| Discharge point:001 | ||||||||||
| LC50 STAT 48HR ACU CERIODAPHNIA | Neither | 30% | ||||||||
| NOEL STATRE 7DAY CHR CERIODAPHNIA | Neither | 49% | ||||||||
| OXYGEN, DISSOLVED (DO) | Neither | 3% | ||||||||
| PH | Neither | 5% | 5% | 8% | 3% | 5% | ||||
| SOLIDS, TOTAL SUSPENDED | Mthly | 125% | 70% | 86% | 699% | |||||
| NMth | 272% | 129% | 25% | 1068% | ||||||
| NITROGEN, AMMONIA TOTAL (AS N) | Mthly | 131% | 220% | 62% | 40% | 1066% | ||||
| NMth | 232% | 480% | 87% | 1020% | ||||||
| PHOSPHORUS, TOTAL (AS P) | Mthly | 20% | 124% | |||||||
| NMth | 70% | 10% | 309% | |||||||
| COPPER, TOTAL (AS CU) | Mthly | 221% | 240% | 266% | 279% | 77% | 151% | 108% | 796% | |
| NMth | 130% | 143% | 162% | 172% | 27% | 80% | 49% | 542% | ||
| COLIFORM, FECAL GENERAL | Mthly | 32% | ||||||||
| NMth | 2000% | 300% | 1483% | |||||||
| BOD, CARBONACEOUS 05 DAY, 20C | Mthly | 97% | 2% | 179% | ||||||
| NMth | 264% | 129% | 223% | |||||||
| SOLIDS, SUSPENDED PERCENT REMOVAL | Mthly | 7% | 33% | |||||||
| Compliance Schedule Violations: | ||||||||||
| ACHIEVED LATE;SUBMIT PART 503 ANNUAL RPT #3 | 02/2002 | |||||||||
| ACHIEVED LATE;SUBMIT SECOND ANNUAL REPORT | 02/2001 | |||||||||
| ACHIEVED LATE;SUBMIT THIRD ANNUAL REPORT | 02/2002 | |||||||||
| NOT RECEIVED ;SUBMIT I/I REPORT #3 | 02/2002 | >>>>>>>> | ||||||||
Effluent violations are displayed as highest percentage by
which the permit limit was exceeded for the quarter.
Bold, largeprint indicates Significant Noncompliance (SNC)
effluent violations.Shaded boxes indicate
unresolved SNC violations.
Effluent violations are indicated by displaying the highest percentage by which the permit limit was exceeded for the quarter. Bold, large print indicates Significant Noncompliance (SNC) effluent violations. For unresolved SNC violations (e.g., violations with no government action against the facility), the table cell is shaded gray. It is possible for a facility to have effluent violations but not be out of compliance at the permit level. This occurs if the exceedances are not significantly over permit limits.
To the right of each parameter/chemical shown with a discharge violation, there is an indicator of what type of measurement was used to determine the violation. "Mnthly" stands for monthly. This means that the exceedance shown in that row was based upon a monthly average of readings submitted by the permittee. EPA generally believes that monthly averages are the most important, because the exceedance represents an average of many readings. "NMth" stands for non-monthly. This is generally a "maximum" amount read during the reporting period (and could indicate a spike that is not continuous). "Neither" denotes other measurements such as a minimum (e.g. pH could be in violation if below the permitted level). Please note that the exceedances shown in the table are the "worst" value within the quarter. Generally the permittee will report three times within the quarter (each month).The following codes are used on the Quarterly Noncompliance Report (QNCR) to indicate compliance status at the facility level. If more than one code applies to a facility, a prioritization is used to determine which codes appears. The order of precedence from most to least important is as follows:
S
= SNC - an enforcement action has been issued, and the facility is not meeting its compliance scheduleE
= SNC - effluent violations of monthly average limits (TRC and chronic)X
= SNC - effluent violations of non-monthly average limits (TRC and chronic)T
= SNC - compliance schedule reporting violationD
= SNC - reporting violation - non-receipt of DMRN
= RNC - Reportable non-complianceP
= Compliance - an enforcement action has been issued, and facility compliance with the action is pending final completionR
= Compliance - an enforcement action has been issued, and the facility has completed all requirements of the actionC
= Compliance - manual override of non-compliance data by state or EPA Region. This manual override status is also indicated by a superscripted "m".Blank = Compliance
SNC categories are shown in RED, Reportable Non-compliance (RNC) categories are shown in ORANGE, On Schedule categories are shown in BLUE, and Compliance categories are shown in GREEN.
The quarterly compliance status for a NPDES permit (under the CWA) is based on two sets of compliance variables in PCS. The first set of variables is automatically generated by PCS. The second set is manually entered into PCS and covers the same eight quarters. Manually entered data values exist in the case of a Single Event Violation. A Single Event Violation is a violation which cannot be classified as a compliance schedule violation or an effluent violation. For example, an unexplained fish kill in a river often results in Single Event Violations for those regulated facilities which release into the river. Manually entered compliance data, if present, override machine-generated compliance data.
A CWA permit is considered non-compliant in a given quarter if a D, E, S, T, X, or N is presented in the Historical Non-Compliance field. A code of C, P, or R indicates compliance (in addition to the automatically generated blank field).
Compliance Schedule Violations
If a facility has been issued an enforcement action and is on a compliance schedule, all non-compliance events related to violations of that schedule in the past two years are listed under the Compliance Schedule Violations section. Text descriptions of the violation(s) are presented below the section heading (e.g., ACHIEVED LATE; NOTICE OF VIOLATION). If the facility is not on such a schedule or is on a compliance schedule but has no schedule violations, this section is not presented. Schedule violations are listed with the beginning and return-to-compliance dates across the eight quarters. If the report shows a right arrow with no closing date, that means that the violation has not been resolved and continues to be active in the data system. If the violation started before the last two years of data and continues into the last two years, the beginning date is listed in QTR1.
Single Event Violations
If the facility is identified as being in violation of CWA requirements not related to their established permit requirements or a compliance schedule, these violations are presented in the section titled Single Event Violations. Text descriptions of the violation(s) are presented below the section heading (e.g., DISCHARGE WITHOUT A VALID PERMIT). If the facility has no single event violations in the past two years, this section is not presented. The date of each single event violation is listed in the table.
