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HomeMy WebLinkAboutSUB200800287 Review Comments Preliminary Plat 2010-04-28*-&A County of Albemarle Department of Community Development Memorandum To: Summer Frederick, Current Development Project Planner From: Phil Custer, Current Development engineering review Date: 28 April 2010 Subject: Fontana Phase 4C, Section 1 Preliminary Plat (SUB- 2008 - 00287) The second submittal of the preliminary plat for Fontana Phase 4c, Section 1, received on 7 April 2010, has been reviewed. Engineering can recommend approval to the plan after the following comments are addressed. 1. The applicant should clarify what exactly this application is. It appears to be a preliminary plat for Sections 1, 2, and 3, but the title says the plan is just for Section 1. (Rev. 1) The applicant has clarified that this application is intended to be a preliminary plat for Section 1. However, I strongly recommend that this submittal become a preliminary plat for all three sections because, in order to receive a grading permit, the ESC plan must match the grading plan. And, a grading permit can only be granted when a preliminary plat (or final site plan) is approved for the land to be disturbed. In other words, an ESC plan cannot be approved unless the preliminary plats for all three sections are valid. 2. A critical slope waiver appears to be necessary. The applicant should provide a request for a waiver to the agent before the next submittal. (Rev. 1) Comment has not been addressed. Once the county has received the critical slope waiver request, we will need to schedule the application for new Site Review Committee and Planning Commission meeting dates. 3. If this plan is intended to be a preliminary plat for section 2, a curb and gutter waiver is required for Cortina Way and Belluno Lane. The applicant should provide a request for a waiver of these standards to the agent before the next submittal. A waiver of sidewalks is also required for these roads as well. (Rev. 1) A waiver is not needed for the lack of curb, gutter, and sidewalk on Cortina Way and Belluno Lane because the sections were approved by the Board of Supervisors as part of the rezoning plan. However, the width of Brunello Court must be increased to the current VDOT standard of 29ft if parking on both sides of the street is desired. 4. Please remove sheets 8.0 and 8.1 from the set. These erosion and sediment control sheets will not be reviewed with the preliminary plat. The erosion and sediment control plan will be reviewed once a WPO application and fee is submitted. For this project, an application cannot be submitted until all off -site improvements have been completed to the County Engineer's satisfaction. (Proffer #8) (Rev. 1) Comment has been addressed. 5. Please provide the date of the topographic survey on the plan. The survey does not appear to be accurate. Lots from previous phases, which have been built out, appear to show before - development grades. The grades on Via Florence appear to be from design drawings from a previous plan. Please show accurate topography. (Rev. I) Comment has been addressed. 6. The plan is lacking analysis of SWM solutions for quality and quantity of runoff. On the next submittal, please supply the County's Modified Simple spreadsheet for each drainage area. SWM facilities should be sited to capture as much runoff as practicable. All lots should be captured. Current Development Engineering Review Comments Page 2 of 4 (Rev. 1) The applicant has responded to this comment by stating that half of the new runoff from this development will drain to a private regional pond. After checking the design file for these ponds, I discovered that the impervious area in the Fontana development is likely underestimated. The previous plan (WPO- 2007 - 00087) assumed that Fontana would be developed with I/z lots with an average impervious area of 25 %. After examining the maps of the previous Fontana phases draining to the facility, it is clear Fontana is an R -4 development with a much higher impervious area. To rectify this likely shortfall, engineering review sees three options the applicant may pursue: - Provide complete stormwater management for the new development on site; - Supply an agreement that demonstrates the owner of TMP 78F -A permits the pond to serve this development's stormwater management requirements AND provide updated calculations for the pond showing that it is large enough to accommodate the Fontana development; or, - Supply an agreement that demonstrates the owner of TMP 78F -A permits the pond to serve this development's stormwater management requirements AND provide supplemental stormwater management on site to account for the SWM shortfall to the satisfaction of engineering review Also, the rear half of the Section 1 Lots are not shown as draining to a SWM facility. If this plan became a preliminary plat for all three sections, the SWM facility on the open space parcel could serve all of the development that drains to the north and east. 7. The grading plan is not adequate. Please address the following items regarding the grading plan: a. The retaining walls are steeper than the maximum allowed grade of 2:1. (Rev. 1) A low maintenance, non -grass groundcover is required on all slopes steeper than 3:1. Please show this groundcover in all required locations on the landscape plan and identify the quantity needed in the Landscape Schedule. b. The building sizes are not representative of what will be constructed. After looking at the aerial photographs for the existing Fontana neighborhood, only about 20% have footprints the size shown in the plan. The grading plan should be representative of what the final buildout of the subdivision will be. Please include walkways, house entrances, wider driveways (show side loaded garages if desired), porches, attached garages, and decks on the grading plan for each building site. (Proffer #2A and #2G) (Rev. 1) The building sizes shown in this latestplan have been designed to match typical units of the Fontana development. However, the applicant has not provided walkways, located house entrances, or specified any small stairway needed for access to homes. Until this is provided, engineering review cannot confirm or comment on the plan's compliance with Proffer 2.G. Preliminarily, it appears as though lots 2, 3, 4, 11, 26, 28, and 29 do not comply with proffer 2G. c. It does not appear that Proffer #2E has been met. Storm sewers through some of the lots south of Brunello Court are required. For instance, it appears a storm sewer is needed between lots 25 and 26. (Rev. 1) Comment has not been addressed. Swales, at least two feet deeper than the elevations adjacent to the houses, are needed between the property lines of lots 19 -27. At the end of each swale, 5 -10ft off of the Brunello Court ROW, provide yard drains and a pipe system that runs parallel to Brunello Court until it reaches the inlet at the Current Development Engineering Review Comments Page 3 of 4 intersection with Fontana Drive. Where necessary, the swales should be riprapped. A 10ft private drainage easement will be needed over each swale and drainage pipe. This grading plan must match exactly what will be constructed. Deviations from the approved grading plan will not be granted by the county. (Rev. 1) Deviations will be allowed but each revision to the final grading plan will require an amendment to the ESC plan (with review fee) and will be given no precedence over other applications in the workload of the engineers. The first revision of grading plan requires the following corrections: d. A yard inlet appears to be needed on Lot 19 to pick up the swale adjacent to the Fontana Drive Extension. e. The grading of lot 18 must be corrected. It does not look like a 596 contour should be drawn. f. Driveways cannot be sloped greater than 10% per Proffer 2G. g. Please provide spot elevations between lots 13 -18 to assure positive drainage into the Via Florence roadside ditch and to the rear of the lots. h. Please provide spot elevations in the roadside ditch of Via Florence to assure positive drainage. i. The house on Lot 9 should be moved so that it matches the grading. j. Please show the trail and all necessary grading for the trail in Sections H and III. k. The grading of the roundabouts in Section 2 must be redone to establish a crown and to flatten the slope to no steeper than 6 %. 1. Extend the ditch from Lot Ito the northern corner of Lot 5. This ditch will require a private easement. m. The grading plan does not assure positive drainage away from each structure which is good, common practice among builders. For instance, the houses on lots 19 -27 all have the proposed topography directing water to their south walls. Please correct the grading plan so that every lot meets R401.3 of the Virginia Residential Building Code. n. The grading plan does not show the house on Lot 34 or the grading needed for the SWM facility. Both of these features must be accurately depicted on the final grading plan. Preliminary SWM calculations are needed to confirm the schematic size of the facility. It appears that the open space parcel may need to be increased to accommodate the SWH facility for this development. o. Please designate the garage FFEs if they differ from the rest of the house. p. Please show all necessary road and driveway culverts with inverts and sizes labeled. q. It appears more walkout basements could be offered than shown in the design. No revision to the plan is currently needed though. However, if a builder wishes to provide a walkout basement in the future on a lot where one was not shown, an amendment to the plan will be needed. 8. The new pedestrian paths must be Class A Type I according to proffer #5. Please update the detail and the plan to show a path 5ft in width with a section of 2" of asphalt overlayed on 4" of gravel. Please also note on the detail that the path is not to have a cross slope of greater than 2 %. The path also appears to be placed on grades steeper than 10 %. (Rev. 1) In detail 7 on sheet 6. 1, please remove the following text. Trail material to be gravel or other approved material. In its place, please specify the following standard. 2 inches of asphalt over a 4" aggregate base at a cross slope no greater than 2 %. 9. The path east of lot 12 must be shown in a loft wide easement. This path also appears to violate Current Development Engineering Review Comments Page 4 of 4 the 10% maximum grade requirement of a Class A Type I trail. (Rev. 1) Comment has not been addressed. The path must be contained within a ]Oft easement. The easement should be Ift off the edge of the trail and Ift off the edge of the ditch. The grading of the ditch must be shown on the plan. Please also show the location of the stairway on the plan with spot elevations at the top and bottom of the stairs. A detail of the stairway is also needed. 10. Please dimension the horizontal roadway alignment to check for compliance with VDOT standards. (Rev. 1) A review of the horizontal road alignment has not been performed because it has not been dimensioned by the applicant. The horizontal dimensions are necessary in order for a preliminary plat to be approved for sections 2 and 3. 11. On the landscape plan please show non - grassed, low maintenance groundcover over all slopes steeper than 3:1. (Rev. 1) The applicant must graphically designate these 2:1 areas on the plan and specify species. Examples of acceptable low maintenance, non - grassed groundcovers can be found in Table 3.37C of the VESCH. The number of plantings needed must also be included in the Landscape Schedule on Sheet C4.4. 12. (Rev. 1) It appears that the future WPO plan will have problems addressing state adequate channel requirements. The construction of a channel from the outlet of the SWM facility to the existing stream may be necessary. This will require a drainage easement if one does not already exist. This is simply an advisory comment. 13. (Rev. 1) Please show the existing inlets along Fontana Drive correctly. If there is not an inlet placed just above the entrance of Brunello Court, one will likely need to be provided to prevent discharge across the entrance when the street plans are reviewed. This is simply an advisory comment. Pilc: E2_ppt_PBC_sub200800287.doc