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MASSACHUSETTS WATER RESOURCES AUTHORITY

Charlestown Navy Yard

100 First Avenue

Boston, Massachusetts 02129

Telephone: (817) 242-8000

June 12, 1987

Environmental Protection Aqency Wa te Manaqement Division John F. Kennedy BuildinqBoston, MA 02129

Attention: Barbarft Newman

Re: Wilminqton Extension Sewer

Dear Madam:

Per your request for information reqardinq the Wilminqton Extension sewer, the Division ubmits the followinqinforaation for your review:

1. Record drawinq of the Wilminqton Ext nsion sewer.

2. Information from the Deer Island Inflow and

Infiltration study pertaininq to the Wilminqton

Extension Sewer.

If this office can be of any further as istance or clarification, please contact at 242-7310, ext. 2279.

of Collection Systems

JPV/lmhenclosure

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Wilmington Extension Sewer (WES). The Wilmington Extension Sewer, not more than 18 years old, is constructed of reinforced concrete pipe and varies in size from a 36-in. diameter pipe at the Woburn/Wilmington town line on New Boston Street to a 48-in. diameter pipe near the Woburn/I Winchester town line, just upstream from the regulation chamber, where it connects to the North Metropolitan Relief Sewer (Section 115A).

I Wastewater is discharged to this interceptor at three member community connections. One of these connections, a 36-in. diameter connection located at ·the Woburn/Wilmington town line on New Boston Street, collectsI wastewater from 100 percent of the ~~were~~ in Wilmington. The remaining two connections to ·t~il(ES Are in Wobu~and are both 18 in. in diameter. Together, these connections receive wastewater from about

I 10 percent of Woburn's sewered area. Millbrook Valley Sewer ~lstem. The MDC interceptor system, serving areas within the communities o Bedford, Lexington, and Arlington, includes theI Lexington Branch, Millbrook Valley, and Millbrook Valley Relief sewers. Wastewater collected by the latter two sewers in this system is transported directly to the North Metropolitan System in Medford, while theI . Lexington Branch Sewer collects wastewater and discharges it to the Alewife Brook System. All the wastewater from this system is eventually discharged to the North Metropolitan System for ultimate treatment and

I disposal at the Deer Island Treatment Facility. Lexinaton Branch Sewer (LBS). The Lexington Branch Sewer, built in

the late 1 OOs, is constructed of vitrified clay and varies in size from a 12-in. diameter to an 18-in. diameter pipe. The interceptor easement starts at the Arlington/Lexington town line and follows Massachusetts Avenue in Arlington to Mystic Street. At this point, the LBS extends in a northeasterly direction to the Mystic River, where it changes direction and runs parallel with the river to the connection with the Alewife Brook Conduit of the Alewife Brook System.

I I A portion of this interceptor, which was taken over by the MDC some time

ago, used to be a town-owned interceptor. Wastewater flow is diverted to the l~illbrook Valley Sewer, while the rest is discharged to the Alewife Brook Conduit. There 1s also an overflow connection to the Millbrook Valley Relief located on Mystic Street.

I Millbrook Valle~ Sewer (MVS). The Millbrook Valley Sewer starts in Lexington near Vinetreet and makes its way to the Lexington/Arlington town line, traveling through low-lying undeveloped areas. Through Arlington, the MVS runs parallel to the Lexington Branch Sewer up to the pointi where it crosses the My.stic River. It then follows High Street in Medford to where it connects to the North Metropolitan Relief Sewer.

I Sections of this sewer were built at different times and constructed with different materials. Sections 77 and 78, built about 1925, are constructed of cast-in-place concrete and vary in size from a 24-in. x 27-in. to a 35-in. x 42-in. extended circle; Sections 79 and 80, also built about

~ I VI-7

analyzed as a system but subdivided into different reaches by tributary community boundaries.

I Stoneham. Section 46 of the North Metropolitan Sewer, Sections 115A and 115B of the North Metropolitan Relief Sewer, and Sections 73, 74, 75, and 76 of the Reading Extension Sewer were all assumed to have anI III rate of 300 gpdlin.-miles for Phase I and Phase II. The Phase I and Phase II III rates are based on an assumed III allowanceI· for interceptors found to have negligible III. In most cases, considerably low III rates were substantiated by visual inspection at various locations along the interceptor.

I Winchester. Sections 44, 44.5, 45, and 46 of the North Metropolitan Sewer, Sections 112, 113, 114, and 115A of the North Metropolitan Relief Sewer, Section 72 of the Reading Extension Sewer, Sections 68, 69, 70,I and 71 of the New ~lystic Valley Sewer, Section 47 of the Cumingsv111e Branch Sewer, Section 86 of the Cummingsville Branch Relief Sewer, and the Mystic Valley Sewer were all computed to have an III rate of 300I gpdlin.-miles in Phase I and 300 gpdlin.-miles in Phase II.

I The Phase I and Phase II III rates are based on an assumed III allowance for interceptors found to have negligible III.

By visual inspection, this interceptor system was found to be in generally good condition.

Medford. Sections 20, 21, and 22 of the North Metropolitan Sewer,

Sections lOS, 106, 106A, 107, 108, 111, and 112 of the North MetropolitanI Relief Sewer, Sections 67, 109, and 110 of the New Mystic Valley Sewer,

the Alewife Brook Conduit, and Section 43.5 of the Alewife Brook Sewer and the Edgeworth Branch Sewer, and Section 77 of the Millbrook Valley Sewer, and Section 91A of the Millbrook Valley Relief Sewer were allI computed to have an III rate of 2,400 gpdlin.-miles in Phase I and 11,600 gpdlin.-miles in Phase II. The rates reflect the overall condition of

I the system.

The rates suggest possible extraneous flow within this system of interceptors, but the source could not be pinpointed.I The magnitude of flow through Medford was great 1n comparison to the

interceptor III. This, and the fact that lesser rates were found in

upstream reaches of this system, indicate that the reported Phase II and Phase II rates may be high. Also, the large volume of flow through

this portion of the system makes more detailed study and possible reha

I bilitation very difficult.

Wilmin¥ton Extension System. Tables V-la amd lb list the computed I/I rates or the Wilmington Extension Sewer (WES).

Woburn. Sections 88, 89, and 90 of the WES and Section llSA of the North Metropolitan Relief Sewer were found to have an I/I rate of

VI-10

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Study Area B - System Description r Study Area B includes tributary areas within the communities of Cambridge, Charlestown, Chelsea, East Boston, Everett, Malden, Medford, Melrose,r Revere, Somerville, Stoneham, Wakefield, and Winthrop. The MDC interceptors in these communities are tributary to the Chelsea Creek Headworks orI the Winthrop Terminal Facility.

I Chelsea Creek Headworks Tributary System Those interceptors tributary to the Chelsea Creek Headworks are the WakeI field Trunk, Wakefield Branch Relief, Malden Branch, Malden Branch Relief, ~h Metrgno11ton, Chelsea Branch, Revere Branch, Cambridge Branch, Charlestown Branch, and Somerville-Medford Branch sewers. All intercep

I tor systems (in both Study Areas Aand B) which are tributary to the Chelsea Creek Headworks are summarized in table VI-1. The North Metro

politan Sewer in East Boston and Winthrop is tributary to the Winthrop

I Terminal Facilities.

Because of frequent choking back of the Chelsea Creek Headworks, gaging could not be accurately carried out near the headworks. This chokingI back has been known to effect the flow in the interceptors as far away as the Edgeworth Branch Sewer in Malden. Therefore, the communities of Chelsea and Everett (80 percent) were analyzed as one gaging area. This gaging area was isolated by gages 2005, 2006, 2007, 2016, 2017, 2023, and the Charlestown Pumping Station as influent monitors and by Parshall flumes at Chelsea Creek Headworks as effluent monitors. Operation of the Chelsea Creek Headworks is schematically shown on Figure VI-1. BeI cause flow measured by the flume at the headworks was used for analysis, it is important to know just how the headworks operate.

I Flows from the tlorth 11etropolitan, Chelsea Branch, and Revere Branch sewers all enter a large mixing chamber (part of an old sand catcher) located in r~arginal Street in front of the headworks, where it mixes with the flow from the North Metropolitan Relief Sewer before entering theI headworks. Once in the headworks, the wastewater flows through fine bar screens, grit collectors, and Parshall flumes before entering Shaft 2 of the North Metropolitan Relief Tunnel. When the Deer Island Main PumpingI Station is overloaded, the headworks cut back the amount of flow which is sent to the treatment facility. The cutting back (choking) is accomplished by lowering gates into the influent channels and allowing only aI set rate of flow to enter the North Metropolitan Relief Tunnel. When choking of the rate of flow entering the headworks occurs, several options may be exercised: storage capacity available in the intercepI tors upstream of the headworks may be used, or the flow may be diverted to the East Boston Pumping Stations via the siphon under the Chelsea River, or flows in excess of the capacity of headworks, interceptors, and pumping stations, may be diverted to the three local outfalls to the Chelsea River. The last option is rarely exercised. The storing of flow

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·I TABLE II-1. CONTINUED

Er+1A Wastewater Treatment Receives WastewaterI ll!!!! Facility Discharges WastewaterFlows From Flows To 43 Wilmington Extension - 100 percent of I Sewer (Sections 88 and Wilmington - Bypass and regulator89) chamber (Section 115A)- About 10 percent of ~

WoburnI 44 Bypass chamber - North Metropolitan - North Metropolitan(Section 115A) Sewer (Section 46) Sewer (Section 46I - North Metropolitan Relief below bypass chamber)Sewer (Section 115A) - North Metropolitan-Reading Extension Relief Sewer

Sewer (Section 72) (Section 115A belowI - Wilmington Extension bypass chamber)

Sewer (Section 88) - Reading Extension

Sewer (Section 72I below bypass chamber)45 Reading Extension - 100 percent of ReadingSewer (Section 72 - Bypass chamber inI above bypass cham - About 30 percent of Woburn (Section 115A)Stonehamber to Section 76) - Overflows to North - About 10 percent of Metropolitan ReliefWakefield Sewer (Section 115B)

- Overflow to Northu Metropolitan Sewer (Section 46)

46I North Metropolitan - Overflows from Reading - Bypass chamberSewer (Sections 115B Extension Sewer (Section (Section 115A)and 115A above bypass 75)I chamber) J - About 30 percent of

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Stoneham - About 15 percent of Woburn

47 North Metropolitan - Overflows from Reading - Bypass chamberSewer (Section 46 Extension Sewer (Section (Section 115A)above bypass cham 73)I ber) - About 25 percent of I

Stoneham

- About 5 percent of Woburn

48 South Charles Relief - North Charles ReliefSewer below Charles - Ward Street HeadworksSewerI crossing (Sections 5 South Charles Reliefand CRC) Sewer above Charles River Crossing

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.t:II::J•zlc 0 0 ~~~~--t;:t=CDCD(')·I -n-•CD -1r!1~''Winchester Mystic Valley MVS t:l:.:North Metropolitan 44,4~,45 46 ~2:North Metropolitan 112,113,1f4, t-~1:111 tnt'"Relief 115A 563.4 ~t'"300I Cummingsville Branch 47 f:m

Cummingsville Branch 86

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Relief ~tReading Extension 72 :lllt:lNew Mystic Valley 68,69,70,71 l:lll:Z: I 0Medford Mystic Valley1 MVS 0 New Mystic Valley 67,109,110 :a t:l

North Metropolitan 20,21,22North Metropolitan 105 , 1 06, 106A I 107 ' 871.41 3,900Relief 108,111,112Alewife Brook 4~Alewife Brook Conduit ABCI Edgeworth Branch (2)Millbrook Valley

Relief 91AI Millbrook Valley 77 Woburn Wilmington Extension 88,89,90

I North Metropolitan 115A 166.5 2,800 ' Relief Lexington Millbrook Valley 85 69.9 300I Arlington Millbrook Valley 82,83,84' /

I .. 77,78,79,80

Millbrook Valley 91A,918,92, / 260.0 4,200Relief 93

Lexington Branch 52,53 /

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-;·r~ - 0-- - - - - - - c; - - - - - - TAIL£ V4a. MDC INTEICEPTOI Ill DETEIMINATION

Study~ A "-I

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Syoe.. o.c:rfptloft MbCw. S.C:t~Gs

Foclii!X No. 2 3

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4

Gao'• Oata 1 I C.O..utatlan of Ill ......

Sll>neham lttodlng Exfwwlan 73?4,75,76 North M.lropalllan 46 Norlh MelropOiitan a.lief ll5A2, lt51 108.7

t ....n,.p_, Station

10211 1027 1029

2.16 --

O,JO 1.08 3.04 I 2.66 1.47 1.84 (3) 0.03 300

Wlncheslw Mystic Valley MVS ......th M.lropalitan 44,14.5,45,46 ,...,..., Melropalllan ltellef ll2,

2113,114,

115A C-'ngovllle lranch 47 c-ingovllle lranch

Relief 86 le:odlng &t.nolan 72 Now Mystic Valley 68,69,:10,71 563.4

1003 1027

1010 1005

1006 10211 -

1008 1022

1009 ---

1007

0.39 1.08

10.40 0.33

4.44 0.70 -

0.29 1.56

17.39

1.14 I 3.04 1.28 1.711 (3) 0.17 300 M.dfonl

~ ... 0

M,lltlc Valley MVS 1008 New Mystic Valley 67,109,110 1007 ......... Metrapalltan 20,21,22 1022 Norlh Melropalitan ltellef 105, 106; 106A, ~

107,108, Ill, 11 1009 Alewife lraak 43.52 -Al-lfe lraak Conduit AIC Al-lfe lroak

• Puoop Station ~lranch (5) 2025 Mlllbroolt Valley ltellef 91A2

871.4 4 1017 Mlllbroolt Valley 772 1018

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2016 -----

o.r. 1.14 1.56

17.39 -

9.49

l.SS 6.81 1.64

9.:10

39.03

- 8.86 4.32 ~.41 2.13 2.13 2,400 Woburn Wll..tnglan b'-IGs

Norlh M.ttapalltan ltellef 88,89 90 IISA:t' 166.5

lOOt 1029

-1010

0.78 3.04

-10.40 6.58 4.04 2.10 0.44 0.44 2,600

wingtan Mlllbroolt Valley 85 69.9 1012 1013 4.26 4.50 0.24 0.15 0.16 (3) 0.02 300

A.llngtan Mlllbroolt Valley

Mlllbroolt Valley ltellef wlngtan er..ch

82,83,84,77, 78,'9,80 91A;l911,92,93 52,53 2~.0

1013

1014 1015

1017

1018 1019

4.50

0.90 0.08

6.11

1.64 1.12 I 4.09 2.78 0.88 0.43 0.43 1,700

Catnloridge, North

lelmant lronch Al-lfe lroak Conduit

Al-lfe lroak CDnduit (lelmont Branch)

Alewife llroak Je- Street lranch

!~ AIC (lelmant)

43 (5) 235.0

., I

1019

1021

-

Al-lfe ........ Pump Station

-

-

1.12

2.76

-

9.49

- I 5.61 4.39 1.62 13) 0.07 300 1Dcahes Indicate that a - - not required an the facility as flow ... -ure.J ek-...,e 1.1 the system. 2only a portion af the -tlan Is located between gages.

~~... • flaw h nat -'-d·4MVS nat Included with ln.-.Nies b this .,.._.

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tuewnoop &4t JO allo::>gll gAIJ.YlLLSlt{UmY 84l Ol &np 81 lJ 'IO!lOU

H aNY f> S'l'l3M 9!4l U'84l J'88JO 8981 8! e6'8WI WIIJ' 84l Jl :30110N

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-~,.. -· .. - ~.).. TABLE VI-4a. INTERCEPI'OR 1/I RATE SUP+fARY

Study Area: A

MOC t.JOC Section In~etceptor Phase!

Camulit_r W8st~ter Facility Number in.-miles gp:lfi!t. -mile

Stoneham Reading Extensioa 73,74,75,76 North Metropolitan 46 108.7 300 North Metropolitan

Relief llSA,llSB

Winchester Mystic Valley MVS North Metropolitan 44,44.5,45,46 North Metropolitan 112,113,114,

Relief llSA · 563.4 300 Clmningsville Branch 47 a..rmingsville JSrancn 86;S

Relief 72•~ 0 Reading Extension 68,69,70,71

New Mystic Valley Medford ·Mystic Valley 1 MVS

New Mystic Valley 67,109,110 North Metropolitan 20,21,22 1 North Metropolitan lOS, 106,106A,l07 871.4 2,400

Relief 108,111,112 Alewife Brook 43.5 Alewife Brook Conduit ABC EdR~rt;h Branch Millbrook Valley

Relief 91A Millbrook Valley 77

Woburn Wilmington Extension 88,89,90 North Metropolitan llSA 166.5 2,600

Relief

l.exington Millbrook Valley 85 69.9 300 1

)1VS not inclu:led with bt::mile; for this system.

Phase II gpd/in. -mile

300

300

11,600

3,700

300

.. .. . -·~

Annual Average

gpd/in. -mile

300

300

3,900

2,800

300

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barcode: *564135*barcodetext: SDMS Doc ID 564135