COBB COUNTY, GEORGIA AND INCORPORATED AREAS. Cobb County REVISED: MARCH 4, 2013 VOLUME 2 OF 4 FLOOD INSURANCE STUDY NUMBER 13067CV002D

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1 VOLUME 2 OF 4 Cobb County COBB COUNTY, GEORGIA COMMUNITY NAME COMMUNITY NUMBER ACWORTH, CITY OF AUSTELL, CITY OF COBB COUNTY (UNINCORPORATED AREAS) KENNESAW, CITY OF MARIETTA, CITY OF POWDER SPRINGS, CITY OF SMYRNA, CITY OF REVISED: MARCH 4, 2013 FLOOD INSURANCE STUDY NUMBER 13067CV002D

2 NOTICE TO FLOOD INSURANCE STUDY USERS Communities participating in the National Flood Insurance Program have established repositories of flood hazard data for floodplain management and flood insurance purposes. This Flood Insurance Study (FIS) report may not contain all data available within the Community Map Repository. Please contact the Community Map Repository for any additional data. The Federal Emergency Management Agency (FEMA) may revise and republish part or all of this FIS report at any time. In addition, FEMA may revise part of this FIS report by the Letter of Map Revision process, which does not involve republication or redistribution of the FIS report. Therefore, users should consult with community officials and check the Community Map Repository to obtain the most current FIS report components. Initial Countywide FIS Effective Date: August 18, 1992 Revised Countywide FIS Effective Date: December 16, 2008 Revised Countywide FIS Effective Date: March 4, 2013

3 TABLE OF CONTENTS Page 1.0 INTRODUCTION Purpose of Study Authority and Acknowledgments Coordination AREA STUDIED Scope of Study Community Description Principal Flood Problems Flood Protection Measures ENGINEERING METHODS Hydrologic Analyses Hydraulic Analyses Vertical Datum FLOODPLAIN MANAGEMENT APPLICATIONS Floodplain Boundaries Floodways INSURANCE APPLICATIONS FLOOD INSURANCE RATE MAP OTHER STUDIES LOCATION OF DATA BIBLIOGRAPHY AND REFERENCES 111 i

4 TABLE OF CONTENTS - VOLUME I Page FIGURES Figure 1 Floodway Schematic 107 TABLES Table 1 Redelineated Streams 8-9 Table 2 Summary of Discharges Table 3 Summary of Stillwater Elevations 42 Table 4 Manning s n Values Table 5 Vertical Datum Conversion 48 Table 6 Floodway Data Table 7 Community Map History 110 TABLE OF CONTENTS - VOLUME II EXHIBITS Exhibit 1 - Flood Profiles Allatoona Branch Allatoona Creek Bishop Creek Blackjack Creek Butler Creek Buttermilk Creek Campground Creek Chattahoochee River Clay Branch Concord Creek Cooper Lake Creek Davis Branch Due West Creek Eastside Creek Elizabeth Branch Favor Creek Florence Branch Gilmore Creek Gordon Branch Panel 01P Panels 02P-12P Panels 13P-14P Panels 15P-16P Panels 17P-22P Panels 23P-26P Panels 27P-28P Panels 29P-33P Panels 34P-35P Panels 36P-37P Panels 38P-39P Panel 40P Panels 41P-43P Panel 44P Panels 45P-46P Panels 47P-48P Panels 49P-50P Panel 51P Panel 52P ii

5 TABLE OF CONTENTS - VOLUME II - continued EXHIBITS - continued Exhibit 1 - Flood Profiles - continued Gordon Creek Gothards Creek Harmony Grove Creek Hope Creek Laurel Creek Liberty Hill Branch Little Allatoona Creek Little Noonday Creek Lost Mountain Creek Luther Ward Branch Panels 53P-54P Panels 55P-56P Panels 57P-58P Panels 59P-60P Panels 61P-64P Panels 65P-67P Panels 68P-71P Panels 72P-75P Panel 76P Panels 77P-79P TABLE OF CONTENTS - VOLUME III EXHIBITS - continued Exhibit 1 - Flood Profiles - continued Milam Branch Mill Creek No.1 Mill Creek No.2 Morgan Lake Tributary Mud Creek Nickajack Creek Noonday Creek Noonday Creek Tributary No. 1 Noonday Creek Tributary No. 3 Noonday Creek Tributary No. 4 Noonday Creek Tributary No. 6 Noonday Creek Tributary No. 7 Noses Creek Olley Creek Olley Creek Tributary Pine Branch Pine Creek Piney Grove Creek Pitner Creek Poorhouse Creek Poplar Creek Powder Springs Creek Powers Branch Panels 80P-82P Panels 83P-84P Panels 85P-86P Panel 87P Panels 88P-94P Panels 95P-100P Panels 101P-110P Panel 111P Panels 112P-114P Panels 115P-117P Panels 118P Panels 119P-120P Panels 121P-132P Panels 133P-137P Panel 138P Panel 139P Panels 140P-141P Panels 142P-145P Panels 146P-147P Panels 148P-149P Panels 150P-151P Panels 152P-158P Panels 159P-160P iii

6 TABLE OF CONTENTS - VOLUME IV EXHIBITS - continued Exhibit 1 - Flood Profiles - continued Powers Creek Proctor Creek Queen Creek Robertson Creek Rottenwood Creek Rubes Creek Rubes Creek Tributary Sewell Mill Creek Smyrna Branch Sope Branch Sope Creek Sweat Mountain Creek Sweetwater Creek Tanyard Creek Tate Creek Terrell Branch Theater Branch Thompson Creek Timber Ridge Branch Trickum Creek Trickum Creek Tributary Vinings Branch Ward Creek Westside Branch Wildhorse Creek Wildwood Branch Willeo Creek Panel 161P Panel 162P-164P Panels 165P-169P Panels 170P-171P Panels 172P-177P Panels 178P-181P Panel 182P Panels 183P-188P Panels 189P-190P Panel 191P Panels 192P-201P Panels 202P-203P Panels 204P-206P Panels 207P-210P Panels 211P-212P Panels 213P-214P Panels 215P-216P Panel 217P Panel 218P Panels 219P-221P Panels 222P-223P Panel 224P Panels 225P-229P Panel 230P Panels 231P-232P Panel 233P Panels 234P-236P Exhibit 2 - Flood Insurance Rate Map Index Flood Insurance Rate Map iv

7 ALLATOONA BRANCH FLOODING CONTROLLED BY ALLATOONA CREEK A B C D STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ALLATOONA CREEK 01P HOLLAND ROAD CONFLUENCE WITH ALLATOONA CREEK LIMIT OF DETAILED STUDY

8 % ANNUAL CHANCE BACKWATER EFFECTS FROM LAKE ALLATOONA (BACKWATER EFFECTS FOR 10%, 2%, AND UNKNOWN) CONFLUENCE WITH LAKE ALLATOONA COBB PKWY FT BACKWATER ALLATOONA CREEK A B C STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ALLATOONA D 02P

9 % ANNUAL CHANCE BACKWATER EFFECTS FROM LAKE ALLATOONA (BACKWATER EFFECTS FOR 10%, 2%, AND UNKNOWN) FT BACKWATER CONFLUENCE WITH LITTLE ALLATOONA CREEK ALLATOONA CREEK E F STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ALLATOONA G 03P

10 % ANNUAL CHANCE BACKWATER EFFECTS FROM LAKE ALLATOONA (BACKWATER EFFECTS FOR 10%, 2%, AND UNKNOWN) COUNTY LINE RD ALLATOONA CREEK FT BACKWATER H I STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ALLATOONA J K L 04P

11 MARS HILL RD ALLATOONA CREEK M N O STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ALLATOONA P 05P

12 ALLATOONA CREEK Q R S T STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ALLATOONA 06P

13 ALLATOONA CREEK STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ALLATOONA 07P STILESBORO RD CONFLUENCE WITH DUE WEST CREEK HADAWAY RD Y Z U V W X

14 KENTUCKY SADDLER CT BURNT HICKORY RD ALLATOONA CREEK AA STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ALLATOONA AB AC AD 08P

15 DUE WEST RD ALLATOONA CREEK AE AF AG STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ALLATOONA AH AI 09P

16 ALLATOONA CREEK STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ALLATOONA 10P MARS HILL RD OLD MOUNTAIN RD CONFLUENCE WITH ALLATOONA BRANCH AN AM AO AJ AK AL

17 HERMITAGE DR HERMITAGE DR ALLATOONA CREEK AP AQ AR STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ALLATOONA AS 11P

18 ALLATOONA CREEK HOLLAND RD AT LIMIT OF DETAILED STUDY AU STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ALLATOONA P

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23 % ANNUAL CHANCE BACKWATER EFFECT FROM LAKE ALLATOONA (BACKWATER EFFECTS FOR 10%, 2%, AND UNKNOWN) CONFLUENCE WITH LAKE ACWORTH NANCE RD BUTLER CREEK FT BACKWATER STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ACWORTH A B C 17P

24 BUTLER CREEK STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ACWORTH 18P ACWORTH CITY LIMIT ACWORTH CITY LIMIT ACWORTH CITY LIMIT COBB PKWY PRIVATE DRIVE M N F G H I J K L

25 JIM OWENS RD BUTLER CREEK O P Q R S STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ACWORTH T U 19P

26 BUTLER CREEK STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ACWORTH 20P KENNESAW CITY LIMIT KENNESAW CITY LIMIT MACK DOBBS RD AA AB V W X Y Z

27 BUTLER CREEK AH AI AC AD AE AF AG STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ACWORTH 21P KENNESAW CITY LIMIT BUTLER BRIDGE WAY KENNESAW CITY LIMIT KENNESAW CITY LIMIT KENNESAW CITY LIMIT KENNESAW CITY LIMIT KENNESAW CITY LIMIT

28 BUTLER CREEK AJ AK AL AM AN STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LAKE ACWORTH 22P PINE MOUNTAIN RD BUTLER CREEK RD BLACK GUM DR SUMIT WOOD DR KENNESAW CITY LIMIT LIMIT OF DETAILED STUDY

29 FLOODING CONTROLLED BY SWEETWATER CREEK 1% ANNUAL CHANCE BACKWATER EFFECTS FROM SWEETWATER CREEK CONFLUENCE WITH SWEETWATER CREEK MAXHAM ROAD SOUTHWEST / STATE HIGHWAY BUTTERMILK CREEK A B STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SWEETWATER CREEK C * * DATA NOT AVAILABLE 23P

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35 CHATTAHOOCHEE RIVER CJ CK CL CD CE CF CG CH STREAM DISTANCE IN MILES FROM WEST POINT DAM 29P LIMIT OF FLOODING AFFECTING COMUNITY COUNTY BOUNDARY INTERSTATE 20 MARTIN LUTHER KING JR. DRIVE CONFLUENCE OF NICKAJACK CREEK BANKHEAD HIGHWAY CI

36 CHATTAHOOCHEE RIVER DC DB CZ DA CW CP CV CM CN CO CQ CR CS CT CU CX CY STREAM DISTANCE IN MILES FROM WEST POINT DAM 30P INTERSTATE ROUTE 285 NORFOLK SOUTHERN RAILWAY JAMES JACKSON PARKWAY NW NORFOLK SOUTHERN PAILWAY SPUR RAILROAD MARRIETTA BOULVARD NW CSX TRANSPORTATION (RAILROAD) CHECKDAM CONFLUENCE OF VINIGNS BRANCH PACES FERRY ROAD NW

37 CHATTAHOOCHEE RIVER DV DW DM DH DL DE DD DF DG DI DJ DK DN DO DP DQ DR DS DT DU STREAM DISTANCE IN MILES FROM WEST POINT DAM 31P COBB PARKWAY (US ROUTE 41) INTERSTATE 75 CONFLUENCE OF ROTTENWOOD CREEK POWERS FERRY ROAD INTERSTATE 285 CONFLUENCE OF SOPE CREEK INTERSTATE NORTH EXPRESSWAY

38 CHATTAHOOCHEE RIVER DY EB DX DZ EA EC ED EE STREAM DISTANCE IN MILES FROM WEST POINT DAM 32P JOHNSON FERRY ROAD MORGAN FALLS DAM CONFLUENCE OF WILLEO CREEK COUNTY BOUNDARY

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41 CONCORD CREEK % ANNUAL CHANCE BACKWATER EFFECT FROM NICKAJACK CREEK I B F A C D E G H STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NICKAJACK CREEK 35P CONFLUENCE WITH NICKAJACK CREEK COVERED BRIDGED ROAD SOUTH HURT ROAD HILL HOUSE ROAD

42 EAST WEST CONNECTOR PRIVATE ROAD HICKS ROAD PRIVATE ROAD AULDYN DRIVE CONCORD CREEK J K L M N O P Q R S STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NICKAJACK CREEK T U V 36P

43 AULDYN DRIVE LIMIT OF DETAILED STUDY CONCORD CREEK U V W X STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NICKAJACK CREEK 37P

44 COOPER LAKE CREEK % ANNUAL BACKWATER EFFECTS FROM NICKAJACK CREEK I F A B C D E G H STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NICKAJACK CREEK 38P CONFLUENCE WITH NICKAJACK CREEK COOPER LAKE ROAD EAST-WEST CONNECTOR DERBY LANE SOUTHEAST CSX TRANSPORTATION

45 COBB COUNTY, GA COOPER LAKE CREEK K N J L M STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NICKAJACK CREEK 39P REED ROAD SOUTHEAST GANN ROAD SOUTHEAST LIMIT OF DETATAILED STUDY

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47 % ANNUAL CHANCE BACKWATER EFFECTS FROM ALLATOONA CREEK CONFLUENCE WITH ALLATOONA CREEK HADAWAY RD DUE WEST CREEK A B C D E F STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ALLATOONA CREEK ACWORTH DUE WEST RD G 41P

48 PAUL SAMUEL RD DUE WEST CREEK H I J K L STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ALLATOONA CREEK 42P

49 LIMIT OF DETAILED STUDY DUE WEST CREEK M N O STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ALLATOONA CREEK 43P

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53 FAVOR CREEK % ANNUAL CHANCE BACKWATER EFFECTS FROM NICKAJACK CREEK D F I A B C E G H STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NICKAJACK CREEK 47P CHURCH ROAD SOUTHWEST CHURCH ROAD RESERVE SMYRNA POWDER SPRINGS ROAD SOUTHWEST

54 FAVOR CREEK J K STREAM DISTANCE IN FEET ABOVE CONFELUNCE WITH NICKAJACK CREEK 48P APARTMENT DRIVEWAY LIMIT OF DETAIED STUDY L

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57 GILMORE CREEK FLOODING CONTROLLED BY CHATTAHOOCHEE RIVER 1% ANNUAL CHANCE BACKWATER EFFECTS FROM CHATTAHOOCHEE RIVER A B C STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH CHATTAHOOCHEE RIVER 51P LIMIT OF DETAILED STUDY PARK CIRCLE WOODLAND BROOK DRIVE NORTHWEST NORTH ELIZABETH LANE NORTHWEST CONFLUENCE WITH CHATTAHOOCHEE RIVER

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61 % ANNUAL CHANCE BACKWATER EFFECTS FROM SWEETWATER CREEK CONFLUENCE WITH SWEETWATER CREEK STOUT PKWY BRIDGE GOTHARDS CREEK STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SWEETWATER CREEK A 55P

62 % ANNUAL CHANCE BACKWATER EFFECTS FROM SWEETWATER CREEK COUNTY BOUNDARY GOTHARDS CREEK B STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SWEETWATER CREEK C 56P

63 HARMONY GROVE CREEK R P Q D E F 860 C B H K M O A G I J L N STREAM DISTANCE IN FEET ABOVE CONFELUNCE WITH WILLEO CREEK 57P CONFELENCE WITH WILLEO CREEK PRIVATE DRIVE PRIVATE DRIVE DAM LONG LAKE DRIVE PRIVATE DRIVE POST OAK TRITT RD MOUNTAIN TRCE MOUNTAIN CREEK DR

64 HARMONY GROVE CREEK W S T U V X Y STREAM DISTANCE IN FEET ABOVE CONFELUNCE WITH WILLEO CREEK 58P MOUNTAIN CREEK DR JOHNSON FERRY RD ZLIMIT OF DETAILED STUDY

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67 LAUREL CREEK STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NICKAJACK CREEK 61P EAST-WEST CONNECTOR 1% ANNUAL CHANCE BACKWATER EFFECTS FROM NICKAJACK CREEK CONFLUENCE WITH NICKAJACK CREEK NORFOLK SOUTHERN RAILWAY HIGHLANDS PARKWAY LAUREL BRIDGE DRIVE SOUTHEAST I J CSX TRANSPORTATION A B C D E F G H

68 LAUREL CREEK N R S 820 M L Q K O P STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NICKAJACK CREEK 62P COOPER LAKE ROAD LAUREL LAKE DAM RYNE PARK COBB DRIVE

69 LAUREL CREEK AA W Z AD T U V X Y AB AC STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NICKAJACK CREEK 63P DRAWBRIDGE ROAD ASHWOOD DRIVE HICKORY CIRCLE

70 LAUREL CREEK AF AH AE AG STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NICKAJACK CREEK 64P LIMIT OF DETAILED STUDY FOREST DRIVE SOUTHEAST LEE STREET SOUTHEAST

71 LIBERTY HILL BRANCH % CHANCE ANNUAL BACKWATER EFFECTS FROM QUEEN CREEK I A B C D E F G H STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH QUEEN CREEK 65P CONFLUENCE WITH QUEEN CREEK MONARCH VALLEY WALK QUEENS MILL ROAD SOUTHEAST BRICKLERIDGE LANE

72 LIBERTY HILL BRANCH STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH QUEEN CREEK 66P HICKORY TRAIL SOUTHEAST J K

73 LIBERTY HILL BRANCH STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH QUEEN CREEK 67P BLACKHAWK TRAIL SOUTHEAST LIMIT OF DETAILED STUDY L M N O

74 % ANNUAL CHANCE BACKWATER EFFECT FROM LAKE ALLATOONA BACKWATER EFFECS FOR 10%, 2%, AND UNKNOWN CONFLUENCE WITH ALLATOONA CREEK FT BACKWATER OLD STILESBORO RD LITTLE ALLATOONA CREEK A B C D STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ALLATOONA CREEK E 68P

75 PITNER RD UNKNOWN RD LITTLE ALLATOONA CREEK F G H STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ALLATOONA CREEK I J 69P

76 LITTLE ALLATOONA CREEK STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ALLATOONA CREEK 70P COLLINS RD PITNER CREEK CONFLUENCE WITH BURNT HICKORY RD K L M N O

77 LITTLE ALLATOONA CREEK STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ALLATOONA CREEK 71P FERNSTONE DR DAM LIMIT OF DETAILED STUDY P Q

78 CONFLUENCE WITH NOONDAY CREEK 1% ANNUAL CHANCE BACKWATER EFFECTS FROM NOONDAY CREEK CANTON ROAD UNNAMED ROAD LITTLE NOONDAY CREEK A B C D STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NOONDAY CREEK E F 72P

79 BLACKWELL RD WORLEY DR LITTLE NOONDAY CREEK G H I J STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NOONDAY CREEK K L 73P

80 LITTLE NOONDAY CREEK STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NOONDAY CREEK 74P RAIL ROAD CONFLUENCE WITH MORGAN LAKE TRIBUTARY PIEDMONT RD Q R M N O P

81 LIBERTY HILL RD S T U V W STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NOONDAY CREEK LIMIT OF DETAILED STUDY LITTLE NOONDAY CREEK 75P

82 LOST MOUNTAIN CREEK % ANNUAL CHANCE BACKWATER EFFECTS FROM WILDHORSE CREEK F A B C D STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WILDHORSE CREEK 76P CONFLUENCE WITH WILDHORSE CREEK LIMIT OF DETALED STUDY FOREST HILL ROAD SOUTHWEST MACEDONIA ROAD SOUTHWEST E

83 % ANNUAL CHANCE BACKWATER EFFECTS FROM MUD CREEK CONFLUENCE WITH MUD CREEK LUTHER WARD BRANCH A B C STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH MUD CREEK D 77P

84 CASTEEL RD VILLA RICA RD BULLARD RD LUTHER WARD BRANCH E F G H STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH MUD CREEK I 78P

85 LUTHER WARD BRANCH J LUTHER WARD RD K STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH MUD CREEK 79P LIMIT OF DETAILED STUDY