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HomeMy WebLinkAboutWPO200500013 Review Comments Road Plan and Comps. 2005-07-29 t • /c1'I kT �'IRGIl`1ZP COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road,Room 227 Charlottesville,Virginia 22902-4596 Phone(434)296-5832 Fax(434)972-4126 Project: WPO-2005-0013,Newcomb Mountain Lane,Private road plan waiver request Plan preparer: Mr. Eliot Fendig,PE,Terra Partners,LLC (fax 434.296.6497) Owner or rep.: Mr. Alex Toomy,The Rocks,LLC (fax 434.296.2814) Mr. Mike Boggs,Haley,Chisholm,Morris (fax 434.974.6849) Date received: 08 July 2005 (road plans rev. date 13 June 2005) Date of Comment: 29 July 2005 Lead Engineer: Allan Schuck,Engineer The Albemarle County Planning Commission, at its' 25 May 2004 meeting, granted approval with conditions to SP-2003-00079. Condition 16 of this approval states: "The extension of Newcomb Mountain Lane as a private road is subject to Planning Commission approval. The Planning Commission shall establish the standard of the private road extension at the time of review." The private road plan,rev. date 13 June 2005, for Newcomb Mountain Road,received on 08 July 2005, -- has been submitted. With this submittal,the applicant has also submitted a waiver request of several of the private road standards. The private road standards are based on the information provided in the 2005 Subdivision Street Requirements,Road Design Manual,Appendix B,for VDOT mountainous terrain standards. The list below shows each individual item that the applicant is requesting a waiver from the private road standards, as requested in a letter dated 23 April 2004 from Mr.Michael Boggs. Private Road Waiver Items: 1. Design Speed: The waiver of the minimum design speed of 20 mph. 2. Maximum Cut or Fill Slope: The waiver for the usage of side slopes greater than 2:1 on slopes. 3. Minimum Radius for Horizontal Curvature: The waiver of the minimum radius requirement of 95' for horizontal curvature allowed in mountainous terrain. 4. Centerline Grade: A waiver of the maximum grade(16%)allowed in VDOT mountainous terrain. 5. Vertical Curve K Factors: A waiver of the minimum values for the"K"factor for vertical sag and crest curves(10 and 20 respectively). 6. Pavement Width and Type: A waiver of the minimum road width of 18'. 7. Shoulder Width: A waiver of the minimum shoulder width of 4' (7' with guardrail). 8. Ditches and Drainage in general: A waiver of the minimum ditch widths and depths(8' and 1'). 9. Guard Posts or Guard Posts and Cable: A waiver of the usage of standard VDOT guardrail. 10. Erosion and Sediment Control: The usage of non-typical E&SC measures during construction of the road. This will require a variance per erosion and sediment control law section 5(VR 625- 02-00). This variance can only be approved by the program authority as stated in the Albemarle County Code, Water Protection Ordinance, 17-204. Page 2 Engineering Review comments of each waiver item: Engineering recommends that the applicant change the alignment of the road between Stations 16+50 to 22+00. The proposed excavation in this area creates a significant amount of environmental degradation on areas of existing critical slopes exceeding 30%grades. It appears that a smaller amount of tree cover removal will occur with the change in alignment because the road can be built in the same area as an existing path. It appears this change in alignment will assist with the lowering of road grades into the steep vertical curve. 1. Design Speed: The applicant wants to use a 15 mph design speed for this private road. Engineering recommends approval to this request. 2. Maximum Cut or Fill Slope: The applicant has requested a waiver for use of a variety of side slopes for this road. The applicant wants to use 1 '/z : 1 side slope in soil, 1:1 slope where needed to limit clearing on stable rock or shale cut slope and mostly on rock fill slopes, and possibly'/2 : 1 on stable rock cut slopes with some possible rock projections. The applicant states that 1 Y2: 1 slope is allowed by the County Engineer on Rosemont Drive. The applicant states that the majority of this road will be constructed on blasted rock and the allowance of steeper slopes prevents the destabilization of the underlying rock during blasting operations. Engineering recognizes the fact that the applicant has used these steep slopes in several projects as well as having County Engineer approval for the construction of steep slopes on Rosemont Drive. Engineering offers the following recommendations for side slopes. • Engineering cannot support the portion of the waiver request for'/2:1 slopes on stable rock cut slopes for safety reasons. • Engineering can support rock projections to occur in slopes. • Engineering can support the remainder of the waiver request with the following conditions: 1. Side slopes in soil shall not exceed 1 '/2:1. 2. Side slopes in rock cut slopes shall not exceed 1:1. 3. This waiver applies only in side slopes where no lawn maintenance is to occur. 3. Minimum Radius for Horizontal Curvature: The applicant wants to use a 35' radius for the centerline of a"switchback curve". The switchback curve,using three(3)horizontal curves,is located on the road plans between Stations 27+51.31 to 29+94.14,on the west side of Newcomb Mountain. The applicant uses 95' radius for the two end curves sandwiched with a 35' radius interior curve,between Stations 28+24 and 29+04. A 95' radius is the minimum allowed in mountainous terrain. County staff visited the roads constructed by the applicant in the Stony Creek portion of Wintergreen Resort. There are two instances where the road alignment in Stoney Creek uses a switchback curve similar to the alignment proposed at this curve. Both occurred at intersections, Valleymont Road and Far Knob Climb and Crawfords Climb and Crawfords Knob. In both cases, the road width was between 26 and 27 feet. The shoulders were 6 to 7 feet wide. The centerline radiuses of these curves were approximately 45 feet. Engineering supports this waiver request with the following conditions: • The three curves are designed with a radius less than 95'. The minimum radius of any of the three curves is 50'. • The vertical grades in this area are adjusted accordingly to review comment#4. • The pavement width from Station 27+00 to 30+00 is 27' wide. It's recommended that the curve be super elevated in this area. 4. Centerline Grade: The applicant is proposing road centerline vertical grades in excess of 16%, which is the maximum grade allowed in VDOT mountainous terrain. The applicant proposes an i Page 3 18%grade for an approximately 287' section of road from Station 23+87.50 to 26+74.34. Engineering cannot support this request. It appears that the road can be designed to meet the 16% grade requirement of the mountainous terrain standard. 5. Vertical Curve K Factors: The applicant has proposed K factors less than the minimum approved values of VDOT. The VDOT road design manual defines the K factor as a coefficient by which the difference in grade may be multiplied to determine the length in feet of the vertical curve which will provide minimum sight distance. At a design speed of 20 mph,the minimum K value for a crest vertical curve is 10 while the minimum K value for a sag vertical curve is 20. The sag vertical curve at Station 21+37.50 to 23.87+50 is the only vertical curve on the entire road that needs a waiver. The applicant is proposing a K value of 7.75 but needs a K value of 20. The Subdivision Ordinance, Section 14-412.A.2,requires K= 15 for a road design for a 3-5 lot subdivision(which also corresponds to the design speed for this road— 15 mph)and allows a minimum 100' sight distance. Engineering recommends that K= 15 for this vertical curve. There are other factors involved that are pertinent to this request. • Moving the overhead utility and pole. It appears that the overhead utility line and corresponding pole(Station 23+10)needs to be moved to allow the road to be constructed. • As stated on page 2, it's recommended that the preceding crest curve be moved to the west along the alignment of the existing road path to avoid the extensive critical slope disturbance(Station 17+00 to 19+50). Damage or loss of significant trees appears to be the same. 6. Pavement Width and Type: The applicant has proposed a pavement width of 14 feet for this private road. The standard pavement width is 18 feet. • Engineering cannot support a reduction of pavement width because of safe and convenient access issues. • Engineering supports the addition of a"traction surface"of stone chips adhered with CRS-2 Liquid Asphalt and Latex additive to the asphalt surface. 7. Shoulder Width: The applicant is proposing a four feet(4')wide fill shoulder and a two feet(2') wide cut shoulder with an additional minimum of 2 feet(2')to the centerline of ditches. Engineering supports this waiver request with the following conditions: • The minimum shoulder width at areas of required guardrail installation is four feet(4'). • The installation of cross culverts or ditch turn-out(releases), in the ditches,at all times where the flow in the ditches exceeds 1 cfs to assist in control of downstream erosion. 8. Ditches and Drainage in general: Engineering can support this waiver with the following conditions: • The typical ditch width and depth can vary from the VDOT standards,but must be specified on the road plans in typical sections for the entire length of road and approved by Engineering. • The installation of cross culverts(as stated above),in the ditches, at all times where the flow in the ditches exceeds 1 cfs. • Engineering can support the use of superelevation. Superelevation locations would need to be clearly specified on the road plans. • The typical pavement crown in steeper areas may be increased to 1/2"per foot. 9. Guard Posts or Guard Posts and Cable: Engineering can support this waiver request with the following conditions: • The guardrail conforms to applicable VDOT standards or the criteria prescribed in the National Cooperative Highway Research Program Report 350. • The guardrail does not create an undue maintenance problem. 10. Erosion and Sediment Control: The erosion and sediment control plan will be reviewed after the road plan design has been finalized and reviewed by the County staff. Any guidance from the Planning Commission for considerations in the reviewing of the E&SC plan submittal is appreciated. t Page 4 Please note that the applicant's E&SC plan needs to meet the required standards or submit a written request for variances with justification, which will be reviewed with the E&SC plan. The above comments are recommendations to the Planning Commission in consideration to their review of the private road design standards for Newcomb Mountain Road. Copy:None File:E2A_rp_ADS_WPO-05-013 Newcomb Mtn Lane