TENNESSEE GAS PIPELINE COMPANY, L.L.C.

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1 TENNESSEE GAS PIPELINE COMPANY, L.L.C. HYDROLOGIC AND HYDRAULIC CALCULATIONS FOR ACCESS ROADS ALONG THE CONNECTICUT PIPELINE EXPANSION PROJECT CONNECTICUT LOOP Submitted by: Tennessee Gas Pipeline Company, L.L.C. Louisiana St, Suite Houston, TX 77 APRIL

2 The attached hydrologic and hydraulic calculations were performed for all field surveyed waterbodies crossed by the Connecticut Pipeline Extension (Project) Hartford County Connecticut. The Project would consist of installing approximately. miles of pipeline looping:. Miles of 6-inch Pipeline Loop in Albany County, New York ( NY Loop ).8 Miles of 6-inch Pipeline Loop in Berkshire County, Massachusetts ( MA Loop ). 8. Miles of -inch Pipeline Loop in Hampden County, Massachusetts and Hartford County, Connecticut ( CT Loop). The primary objective of the attached calculations was to evaluate the amount of runoff due to the construction of permanent access roadways to the pipeline, and to size flume pipes at each waterbody crossing to convey, at a minimum, normal flow safely under the access roads. A typical flume installation will consist of sand bag cofferdams placed at the upstream and downstream limits of the construction workspace and the installation of the pipe specified in the design.

3 DESIGN CRITERIA AND METHODOLOGY The following design criteria and methodology was used to perform the calculations:. Hydrologic Methodology Hydrologic calculations were performed using a combination of the Rational Method, the NRCS (SCS) Peak Flow Method, USGS StreamStats, and USGS StreamStats with HydroCAD v... The specific method used to calculate the design flows for each waterbody varied based on parameters such as the watershed size, waterbody slope, basin elevation, and ground cover type (e.g. pasture, forest, urban). a. Rational Method: Q=CIA Q = flow (cubic feet per second - cfs) C = runoff coefficient A = drainage area (acres ac) I = rainfall intensity (inches per hour in/hr) This method was used for drainage areas up to acres in size NOAA Technical Memorandum NWS Hydro- was used to determine I in Connecticut County of Hartford. The following Runoff Coefficients were used: Cover Type Slope Range (%) Hydrologic Soil Group* Runoff Coefficient Pasture % - 6% D. Forest % % D. Forest > % D.8 Gravel %-% N/A.8 *Hydrologic Soil Group D was used for a conservative approach. Time of Concentrations were calculated using the following: o Sheet Flow: Manning s Kinematic Solution Maximum (max) sheet flow length of ft

4 o Shallow Concentrated Flow The travel time for shallow concentrated flow was calculated by dividing the travel path length by a calculated velocity. The velocity for specific cover types were calculated using Manning s equation. o Channel Flow As upstream channel morphology is not constant, the travel time for Channel flow was calculated by assuming a channel velocity of. ft/s and applying it to the shallow concentrated flow formula. b. NRCS (SCS) Peak Flow Method: The computer program HydroCAD, Version., was used to determine the peak flow discharges for the watershed. HydroCAD is a program which employs TR- methodology which uses the unit-hydrograph runoff procedure. As with TR-, the HydroCAD peak flow discharges are dependent upon parameters such as watershed size, the curve number for a given watershed, time of concentration, available flood storage, rainfall storm type, rainfall intensity and storm duration. The following curve numbers were used: Cover Type Hydrologic Soil Group* Curve Number (CN) Woods D 8 Pasture D 89 Urban D 98 *Hydrologic Soil Group D was used for poor soil conditions, and a conservative approach. Depths were used in conjunction with a -hour storm duration. The Time of Concentration was calculated using the same methodology used for the Rational Method. c. USGS StreamStats for Connecticut StreamStats is a Web-based tool developed by the USGS and Environmental Systems Research Institute, Inc. (ESRI). This map-based Web application was designed to make it easy for users to obtain stream flow statistics, drainage-basin characteristics, and other information for userselected sites. StreamStats utilizes previously published information from gaging stations and previously gathered basin characteristics to develop stream flow statistics utilizing the

5 appropriate regression equations to compute the stream flows. The StreamStats flows will only be utilized where the drainage area falls within the acceptable ranges for Mean/Base-Flow or for Peak Flow. Drainage areas outside the acceptable ranges generate flows that are based on extrapolations with unknown errors. d. Design Frequency: The design frequency utilized in the design varied based on the U.S. Weather Bureau Technical Paper. A -year design, a -year, and a -year maximum design storm were utilized for all watershed classifications. Average daily flow calculations were also performed for larger watersheds where the - and -year storms resulted in flows that cannot be completely passed within the designed pipes and it is unlikely that a -year or -year storm event will occur during the crossing.. Hydraulic Calculations The temporary flume pipes were sized using the Federal Highway Administration (FHWA) HY-8 computer program. HY-8 is a culvert analysis program that automates the design methods described in HDS No., Hydraulic Design of Highway Culverts.. Summary and Results The post construction hydrology of the access road areas are not significantly altered by the construction of the access roadways. The flows, summarized in the table below, are not significantly higher due to the construction of the access roadways and will not negatively impact the surrounding areas. See attached table on the next page, for flume pipe and stream crossing details. Pre-Development Flow CT PAR- Post-Development Flow Difference Difference (cfs) (cfs) (cfs) ( % ) -Year Year Year

6 X PP X X X X X X X X X X X X X X X X X AREA: CT PAR- // // // AREA: CT PAR-A // // // // // // // // //

7 S S S S CT PAR-a PRE CT PAR- PRE CT PAR- Post CT PAR-a POST R 6R PRE POST Subcat Reach Pond Link Routing Diagram for C-ENG-C78CT-PAR, Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC

8 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Time span=.-. hrs, dt=. hrs, points Runoff by Rational method, Rise/Fall=./. xtc Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment S: CT PAR- PRE Subcatchment S: CT PAR- Post Subcatchment S: CT PAR-a PRE Subcatchment S: CT PAR-a POST Reach R: PRE Reach 6R: POST Runoff Area=9.8 ac.8% Impervious Runoff Depth=." Flow Length=,7' Tc=9.6 min C=. Runoff=.67 cfs.6 af Runoff Area=9.8 ac.8% Impervious Runoff Depth=." Flow Length=,7' Tc=9.6 min C=. Runoff=.96 cfs.8 af Runoff Area=. ac.% Impervious Runoff Depth=." Flow Length=9' Tc=. min C=. Runoff=.7 cfs. af Runoff Area=. ac.% Impervious Runoff Depth=." Flow Length=9' Tc=. min C=.8 Runoff=.8 cfs.7 af Inflow=.9 cfs. af Outflow=.9 cfs. af Inflow=.79 cfs.7 af Outflow=.79 cfs.7 af Total Runoff Area =.788 ac Runoff Volume =.6 af Average Runoff Depth =." 99.6% Pervious =.66 ac.7% Impervious =.6 ac

9 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Subcatchment S: CT PAR- PRE.67 cfs Runoff CT- -yr Duration= min, Inten=. in/hr Runoff Area=9.8 ac Runoff Volume=.6 af Runoff Depth=." Flow Length=,7' Tc=9.6 min C=.

10 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Subcatchment S: CT PAR- Post.96 cfs CT- -yr Duration= min, Inten=. in/hr Runoff Area=9.8 ac Runoff Volume=.8 af Runoff Depth=." Flow Length=,7' Tc=9.6 min C=. Runoff

11 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Subcatchment S: CT PAR-a PRE cfs Runoff CT- -yr Duration= min, Inten=. in/hr Runoff Area=. ac Runoff Volume=. af Runoff Depth=." Flow Length=9' Tc=. min C=..

12 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page 6 Subcatchment S: CT PAR-a POST cfs CT- -yr Duration= min, Inten=. in/hr Runoff Area=. ac Runoff Volume=.7 af Runoff Depth=." Flow Length=9' Tc=. min C=.8 Runoff..

13 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page 7 Reach R: PRE 6.9 cfs Inflow Area=.89 ac Inflow Outflow

14 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page 8 Reach 6R: POST 6.79 cfs Inflow Area=.89 ac Inflow Outflow

15 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page 9 Time span=.-. hrs, dt=. hrs, points Runoff by Rational method, Rise/Fall=./. xtc Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment S: CT PAR- PRE Subcatchment S: CT PAR- Post Subcatchment S: CT PAR-a PRE Subcatchment S: CT PAR-a POST Reach R: PRE Reach 6R: POST Runoff Area=9.8 ac.8% Impervious Runoff Depth=.9" Flow Length=,7' Tc=9.6 min C=. Runoff=6.8 cfs.86 af Runoff Area=9.8 ac.8% Impervious Runoff Depth=." Flow Length=,7' Tc=9.6 min C=. Runoff=7.7 cfs. af Runoff Area=. ac.% Impervious Runoff Depth=." Flow Length=9' Tc=. min C=. Runoff=. cfs.9 af Runoff Area=. ac.% Impervious Runoff Depth=.8" Flow Length=9' Tc=. min C=.8 Runoff=. cfs.68 af Inflow=7.89 cfs.6 af Outflow=7.89 cfs.6 af Inflow=8.8 cfs.79 af Outflow=8.8 cfs.79 af Total Runoff Area =.788 ac Runoff Volume =.9 af Average Runoff Depth =." 99.6% Pervious =.66 ac.7% Impervious =.6 ac

16 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Subcatchment S: CT PAR- PRE cfs CT- -yr Duration= min, Inten=. in/hr Runoff Area=9.8 ac Runoff Volume=.86 af Runoff Depth=.9" Flow Length=,7' Tc=9.6 min C=. Runoff

17 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Subcatchment S: CT PAR- Post cfs Runoff 7 6 CT- -yr Duration= min, Inten=. in/hr Runoff Area=9.8 ac Runoff Volume=. af Runoff Depth=." Flow Length=,7' Tc=9.6 min C=.

18 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Subcatchment S: CT PAR-a PRE. cfs Runoff CT- -yr Duration= min, Inten=. in/hr Runoff Area=. ac Runoff Volume=.9 af Runoff Depth=." Flow Length=9' Tc=. min C=.

19 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Subcatchment S: CT PAR-a POST. cfs Runoff CT- -yr Duration= min, Inten=. in/hr Runoff Area=. ac Runoff Volume=.68 af Runoff Depth=.8" Flow Length=9' Tc=. min C=.8

20 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Reach R: PRE cfs Inflow Area=.89 ac Inflow Outflow 6

21 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=. in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Reach 6R: POST cfs Inflow Area=.89 ac Inflow Outflow 7 6

22 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=.9 in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page 6 Time span=.-. hrs, dt=. hrs, points Runoff by Rational method, Rise/Fall=./. xtc Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment S: CT PAR- PRE Subcatchment S: CT PAR- Post Subcatchment S: CT PAR-a PRE Subcatchment S: CT PAR-a POST Reach R: PRE Reach 6R: POST Runoff Area=9.8 ac.8% Impervious Runoff Depth=.8" Flow Length=,7' Tc=9.6 min C=. Runoff=.9 cfs.67 af Runoff Area=9.8 ac.8% Impervious Runoff Depth=.9" Flow Length=,7' Tc=9.6 min C=. Runoff=.67 cfs.76 af Runoff Area=. ac.% Impervious Runoff Depth=.88" Flow Length=9' Tc=. min C=. Runoff=.8 cfs. af Runoff Area=. ac.% Impervious Runoff Depth=." Flow Length=9' Tc=. min C=.8 Runoff=. cfs.9 af Inflow=.76 cfs.777 af Outflow=.76 cfs.777 af Inflow=.78 cfs.8 af Outflow=.78 cfs.8 af Total Runoff Area =.788 ac Runoff Volume =.6 af Average Runoff Depth =.89" 99.6% Pervious =.66 ac.7% Impervious =.6 ac

23 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=.9 in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page 7 Subcatchment S: CT PAR- PRE cfs CT- -yr Duration= min, Inten=.9 in/hr Runoff Area=9.8 ac Runoff Volume=.67 af Runoff Depth=.8" Flow Length=,7' Tc=9.6 min C=. Runoff

24 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=.9 in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page 8 Subcatchment S: CT PAR- Post cfs CT- -yr Duration= min, Inten=.9 in/hr Runoff Area=9.8 ac Runoff Volume=.76 af Runoff Depth=.9" Flow Length=,7' Tc=9.6 min C=. Runoff

25 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=.9 in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page 9 Subcatchment S: CT PAR-a PRE.8 cfs Runoff CT- -yr Duration= min, Inten=.9 in/hr Runoff Area=. ac Runoff Volume=. af Runoff Depth=.88" Flow Length=9' Tc=. min C=.

26 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=.9 in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Subcatchment S: CT PAR-a POST. cfs Runoff CT- -yr Duration= min, Inten=.9 in/hr Runoff Area=. ac Runoff Volume=.9 af Runoff Depth=." Flow Length=9' Tc=. min C=.8

27 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=.9 in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Reach R: PRE.76 cfs Inflow Area=.89 ac Inflow Outflow

28 C-ENG-C78CT-PAR CT- -yr Duration= min, Inten=.9 in/hr Printed 7// HydroCAD. s/n HydroCAD Software Solutions LLC Page Reach 6R: POST 6.78 cfs Inflow Area=.89 ac Inflow Outflow

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