20150389 Ver 1_Geotech Justification - BR 253 and BR 101 Permits_20150423

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Date: March 11, 2015
Memorandum To
Attention:
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o£SIGN AHD kNG1HEERIHG ZBAVIGES
Mr. Jerry Parker, Division Environmental Supervisor — Division 7
Ms. Nikki Thomson, Environmental Specialist
From: H. Andy Haymes, PE — Haymes Brothers, Inc.
T. N. Parrott, PE —Summit, Infrastructure Engineering Bra ch ���
Don Dewey, PE — Summit, Geotechnical Engineering Branch��,;�
Subject: 17BP.7.R.63 Express Design Build, Year 2, Division 7 Set B
Feasibility of Bottomless Culvert Construction — BR 000253 and BR 670101
The Request for Proposal for the referenced contract identified fourteen (14) existing bridges for
replacement with bottomless culverts in Alamance and Orange Counties. In designing and
constructing the affected bridge replacements, some sites have been found not conducive to
bottomless culvert construction due to deep/low non-scourable rock elevations. To date, NCDOT
has revised five (5) of the proposed structures to four-sided culverts due to actual foundation
conditions (deep/low non-scourable rock elevations) encountered.
Anticipated rock elevations have been evaluated at all remaining sites. Tabulated below are the
anticipated rock elevations at BR 000253 (Alamance) and 670101 (Orange):
BR 000253 — SR 2178 Rumley Road, Alamance County
NWS Geotechnical Data Depth Proposed Culvert Footing Estimated Rock Depth
Elev Boring / Rock to Rock Location Bottom of Footing Elev. at Footing to Rock
Sounding Elev. * (ft) Elevation Key (ft)
447.3 Boring EB1-A 445.9 1.4 Inlet 446.39 444.9 (approach) 1.49
Boring EB1-B 442.0 5.3 445.5 (trailing) 0.89
Boring EB2-A 449.1 -1.8 Outlet 446.35 444.2 (approach) 2.15
Boring EB2-B 446.6 0.7 445.6 (trailing) 0.75
Rod RS-1 446.6 0.7
Rod RS-2 446.5 0.8
Rod RS-3 445.2 2.1
Rod RS-4 445.9 1.4
* Weathered Rock Elevation
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BR 670101— SR 1723 New Hope Church Road, Orange Caunty
NWS Geotechnical Data Depth Proposed Culvert Footing Estimated Rock Depth
Elev Boring / Rock to Rock Location Bottom of Footing Elev. at Footing to Rock
Sounding Elev. * (ft) Elevation Key (ft)
473.4 Boring E61-A 474.3 -0.9 Inlet 472.67 472.3 (approach) 0.37
Boring E61-B 473.0 0.4 471.4 (trailing) 1.27
Boring E62-A 474.3 -0.9 Outlet 472.67 469.6 (approach) 3.07
Boring E62-B 472.6 0.8 471.3 (trailing) 1.37
Rod RS-1 470.3 3.1
Rod RS-2 472.4 1.0
Rod RS-3 472.3 1.1
* Weathered Rock Elevation
Enclosed with this memorandum are the geotechnical inventories for each project.
Based on the information tabulated above, the elevation of non-scourable rock suitable for
keying bottomless culvert foundations is proximate to the natural water surface elevations and,
thereby, proposed bottom of strip footing elevations. These conditions will allow for effective
construction of the reinforced concrete strip footings parallel to the streams as required for
bottomless culverts. The aforementioned conditions (rock elevations) are consistent with
recognized NCDOT policy for bottomless culvert applications, such policy being the presence of
non-scourable rock within approximately three (3) feet of natural water surface elevation.
Therefore, we request that BR 000253 and BR 670101 be permitted as bottomless culverts.
Please advise if additional information is required to expedite these permits.
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