PRELIMINARY HYDRAULICS STUDY FOR ENVIRONMENTAL IMPACT ADDENDUM #1 – Addition of Site 1A Downstream of Site 1 in original September 17, 2014 Report SITE 1A – MIDDLE CREEK CROSSING AT SUNSET LAKE ROAD (SR 1301) TIP PROJECT NO. R-2721, R-2828 & R-2829 WAKE AND JOHNSTON COUNTIES TRIANGLE EXPRESSWAY SOUTHEAST EXTENSION MULKEY, INC. 6750 Tryon Road P.O. Box 33127 Raleigh, NC 27636 (919) 851-1912 February 16, 2015 TABLE OF CONTENTS I. Hydraulic Aspects of Environmental Impact II. Preliminary Design and Assessment Checklist III. Project Maps IV. Site Information (Sites 1A) Each site includes the following information (if applicable): Plan View of Site Quad Map Hydraulic/Hydrologic Design FEMA/ FIS Information Photos/Field Notes Miscellaneous I. Hydraulic Aspects of Environmental Impact HYDRAULIC ASPECTS OF ENVIRONMENTAL IMPACT OF THE TRIANGLE EXPRESSWAY PROTECTED CORRIDOR BETWEEN NC 55 BYPASS (HOLLY SPRINGS) AND US 64 BYPASS (KNIGHTDALE). TIP PROJECT NO. R-2721, R-2828 AND R-2829 The North Carolina Turnpike Authority (NCTA) proposes to construct a multi-lane facility on new location between NC 55 in Apex and US 64/264 in Knightdale. The proposed typical section that is being considered for the project is a 6 lane median divided facility. The length of the proposed corridor is approximately 30 +/- miles. See the attached quad map for specific locations of the sites. All of the crossings are located in the Neuse River Basin. It was discovered during a recent Agency field meeting that during Functional Designs a project corridor was extended to cover the downstream crossing of Site 1. This created Site 1A, Sunset Lake Road over Middle Creek. This site was never studied in the original report, therefore, it is now being investigated as an additional site (Site 1A), as Addendum #1. The staff of Mulkey, Inc. recently conducted a field investigation and preliminary hydraulic study for the subject stream crossing. In consideration of all aspects noted below, the hydraulic recommendations are summarized as follows: Site 1A is a crossing of Middle Creek on an existing location; Sunset Lake Road. The normal water depth at the proposed site is 2.5 feet. The channel has a base width of 25 feet and a depth of 4.5 feet. Average upstream/downstream top of bank to top of bank measures approximately 35 feet. Recent drift was observed to be 5.0 feet above the stream bed. Debris potential is high and existing timber debris was noted in the upstream portion of the channel during recent site visit. The drainage area for this crossing is 3,554 acres (5.55 square miles). A majority of the area is zoned as Residential or Mixed Use. This crossing is located below headwater. Based on preliminary hydraulic analysis of this site, it is recommended that the proposed structure be a 100 foot bridge. Further detailed analysis will be required during final design in order to adequately address all the impacts associated with the floodplain. The creek is in a FEMA detailed study Special Flood Hazard Zone AE containing a published floodway. The creek is listed on the North Carolina Division of Water Quality (NCDWQ) 303(d) list (27-43-15-(1)b1) for impaired streams. This stretch of creek is located in Class C and NSW per NCDWQ classifications for this site. Wake County participates in the National Flood Insurance Regulatory Program. Results of this study were based upon the current Effective FIRM maps for Wake County. The Hydraulics Unit will coordinate with the Federal Emergency Management Agency (FEMA) to determine if a Conditional Letter of Map Revision (CLOMR) and a subsequent final Letter of Map Revision (LOMR) are required for the project. If required, the Division will submit sealed as-built construction plans to the Hydraulics Unit upon project completion certifying the project was built as shown on construction plans. 2 Wetlands were observed sporadically through the entire corridor. NCDOT “Best Management Practices for the Protection of Surface Waters” will be utilized throughout the life of the project. Erosion and sedimentation will be controlled through the specification, installation, and maintenance of more stringent erosion and sedimentation control methods. Existing drainage patterns will be maintained to the extent practicable. Groundwater resources should not be affected by the project, as the roadway approaches are primarily on fill. Nutrient sensitive buffers are located throughout the entire project. There are no water supply watershed critical areas located downstream of this project, therefore Hazardous Spill Basins are not required for this project. It is anticipated that construction of the project will require a United States Army Corps of Engineers 404 individual permit and a 401 Water Quality Certification. 3 R-2721, R-2828, & R-2829 TriEx SUMMARY TABLE OF HYDRAULIC RECOMMENDATIONS EXISTING DA FLOOD DETAILED RECOMMENDED SITE STREAM STRUCTURE (SQ. MI.) ZONE STUDY STRUCTURE 2@142”x 91” 5.55 Yes 1A Middle Creek Yes 100’ Bridge CSPA (3,554 Ac.) (Zone AE) II. Preliminary Design and Assessment Checklist III. Project Maps IV. Site Information (Site 1A) Site 1A North Carolina 12/19/2014 PROJECT NAME: Triangle Expressway SE Ext STREAM NAME: Middle Creek REGION: BLUE RIDGE Site #1A ENGLISH Drainage Area = 5.55 sq. miles METHOD USED: Fact Sheet 007-00 USGS RURAL REGRESSION EQUATIONS (OLD) RURAL EQUATIONS Report 01-4207 FREQUENCY Sand Hills Coastal Plain Blue Ridge FREQUENCY Blue Ridge Coastal Plain Sand Hills (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) 2YR 104.31 205.00 470.62 2YR 449.60 205.03 113.50 5YR 172.87 403.98 781.86 5YR 772.15 383.01 184.52 10YR 228.91 586.47 1044.00 10YR 1038.65 539.38 240.71 25YR 312.23 900.89 1434.92 25YR 1437.73 776.38 321.71 50YR 384.25 1182.40 1769.97 50YR 1787.40 989.95 392.18 100YR 465.87 1530.48 2164.26 100YR 2174.40 1234.57 464.95 200YR 574.08 1956.41 2600.89 200YR 2609.58 1514.38 550.85 500YR 694.24 2635.72 3286.80 500YR 3271.56 1946.94 678.13 USGS URBAN REGRESSION EQUATIONS BDF= 11 ( These Equations are used only for comparison) FREQUENCY Sand Hills Coastal Plain Blue Ridge (cfs) (cfs) (cfs) 5YR 602.35 1167.88 1954.67 10YR 712.90 1499.02 2364.13 25YR 877.79 2049.04 2973.56 50YR 1033.03 2567.49 3559.78 100YR 1229.65 3261.09 4332.70 200YR 1996.13 4197.26 6619.55 (Based on 2.80xQ10) 500YR 1706.62 5096.07 6107.34 NC REGRESSION EQUATIONS (% Impervious) USGS Fact Sheet 007-00 % Impervious = 45 FEMA FREQUENCY Sand Hills Coastal Plain Blue Ridge Discharge Used FREQUENCY Disharges (cfs) (cfs) (cfs) 5YR 1452.53 1848.99 2236.55 10YR 1713.22 2259.51 2662.42 10YR 1050 25YR 2029.25 2918.73 3415.85 50YR 2150 50YR 2286.84 3289.62 3749.97 3700 100YR 2800 100YR 2495.83 3621.47 4037.27 500YR 5200 200YR 4797.01 6326.62 7454.77 (Based on 2.80xQ10) 500YR 6270.38 8269.80 9744.45 (Based on 3.66xQ10) 2050000 FEET 2060000 FEET 710000 FEET 78°49'30"W 78°49'0"W 78°48'30"W 78°48'0"W 710000 FEET E a r t n h L D n r o d 35°42'0"N 35°42'0"N n r e H Dezola St T A reys Ct l l e n h u r s T t im P pa l ZONE AE ni Tr l F am il y C ir cle Rd r D r n D o i e d s s s a l R l h i u C c M r s e g Middle n Millsford Hill Pl g P li n l i i Creek r h e S v Ct e s L Drexel Hill Ct ak O r o Bobbitt Rd o m n Wayfield Ln h L t k u l a Satori Way o t S W C y Concerto e l TOWN OF Smith Rd s n APEX ETJ A 370467 TOWN OF Denham Walk Ct Morganford Pl Dr APEX ETJ se ha y C 370467 lb Co O Rh r yth c m h Dr e s t r a C t October Glory Ln Chaswold Ct 35°41'30"N Ferrington Ct 35°41'30"N S um m e ning Mist Ct r Trackimire Ln Mor R Dinsorette Ln id Lorry Ln Moss MountainLn g Lacuna Woods Ln e Alpharetta Trl C Str Lianfair L t ayw n hit Brook Cross Dr e A Hearn Ct v Peachstone Ct e Derry Down Ln TOWN t Co C ckle r Burr Dr OF CARY e f i n Park D n on r i 370238 ni u M e F Merion Station Dr n R o L r r r Reunion Arb o y m Rig Geoffrey Ct hters Mi a ll W Stephenson Rd s ay y Daysprings Ct t a T W Turnbuckle Ct r l d r y o a R f e Storemont Way t s e W u Bizzell Ct e g n d i i n o W R L n High Ramble Ln n s io w W n o Inkberry Ct eu oods Tr R d l a e M n R o Little White Pine Ct i e n u d n Portwind Ln n Gallent Hedge Trl L io u R Ballytore Dr n Crossvine Ct C e e R R a re n e e z k u a Fargale Ln Carlotta Ct o P n l Presenteer Trl t k io P s y n H y a r rd r e Lynnford Dr ZONE AE nri e d h ge r C C t D k o TOWN OF o r b y TOWN OF l APEX l od Dr Tear Drop C ir o Thriftwo 370467 APEX ETJ H t n 370467 WAKE COUNTY C L Rollsby Ct y e e v UNINCORPORATED AREAS n o r e D Co P g ralb 370368 n S er i ry r u C p n i s r S Dr D ven h o Ha i ves n e C r r e D s t t es C cr t rn Middle Creek ho r T D p a c d S 35°41'0"N 35°41'0"N n t i o n Arro W whe Ba e a Weeping Oak Ct d D nview Ln c r r e H e olly k hock Ln D Kildee Ct r Monarc t h Birch C Dr e t a Ness Dr G s le b n a Lindell Dr G L e Lockett Ln n Ct i lsby R P oo id G g s e g L a n k i e K D Greycrest Ct r Butt C erbiggins Ln olonia l Oa ks Dr Craig Dr Shadow Mist Ct Stargazer Ct r D 2488 t i s Florians Dr D e u r o t n c F B r L Jasmine Rose Ct h Ci k a E t y c is l l Hi M l e m a ghland y l 351.2 l l B S a Dr han non V r Way h D c r e o Misty Lake St D t n n s Sunset Lake Rd i TOWN OF HOLLY e n Hazelmere Dr r o o G y P n m a t L SPRINGS A e m W s d w o r D k n e d o C r Gingerlilly Ct o u f F o d 370403 air a i f w o S e n r a d to P l s e e d D R y r M r L u e Osterville Dr b i l n rm P z F w Sto e n g i in r n e e N v e E k f c l y M R d Logans Call Ct Heritage Meadows Ln Meadows Heritage Fountain Springs Rd Dr TOWN OF ds ar Riley Oaks Ln w Danesway Dr ZONE AE d HOLLY SPRINGS E Dr r s r D ni 370403 o n D i a lag y s el H l l B Turner Dr a TOWN OF HOLLY F r ermo C e l t r C a Arbor Creek D v SPRINGS ETJ P i ap R r 370403 i Dr t C Holmby Ct TOWN OF HOLLY w Ct e o t l l a a 35°40'30"N 35°40'30"N g M s SPRINGS G C p r o o WAKE COUNTY e o e h s 370403 k S Hav e UNINCORPORATED AREAS en Dr b e r r B y o t 370368 t l e D r r b D t e r h Ct lo C t us el a p Middle Creek a g C f a e 700000 FEET L 700000 FEET 78°49'30"W 78°49'0"W 78°48'30"W 78°48'0"W 2050000 FEET 2060000 FEET This digital Flood Insurance Rate Map (FIRM) was produced through a unique cooperative partnership between the State of North Carolina and the Federal Emergency Management Agency (FEMA).