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Home My WebLink AboutWPO200900061 Review Comments Mitigation Plan 2011-04-15� OF AL ,. vIRGI1`IZP COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road Charlottesville, Virginia 22902 -4596 Phone (434) 296 -5832 Fax (434) 972 -4126 Project: North Pointe Stream Crossing [WPO- 2009 - 00061] Plan preparer: Mr. James Fulcher; TEC Inc. and Field Works Owner or rep.: Neighborhood Investments, NP, LLC Developer: Charles Rotgin; North Pointe Charlottesville, LLC c/o Great Eastern Management Company Plan received date: (Rev. 2) 17 March 2011 (Rev. 1) 25 October 2010 7 December 2009 Date of comments: (Rev. 2) 15 April 2011 (Rev. 1) 23 November 2010 14 January 2010 Reviewer: Phil Custer The second resubmittal of the Mitigation Plan for the North Pointe Stream Crossing project, submitted on 17 March 2011, has been reviewed. The following comments must be addressed before approval of the set is given: 1. The current plan does not appear to consider all proposed impacts to the buffer according to the latest ESC plan. Since the December 7`" submittal, a sediment trap and new channel have been added within the buffer and must be accounted for. Also, please consider the encroachment of the turn lane into the stream buffer in your calculation of buffer impacts. Use the limits of disturbance from both ESC plans prepared by WW Associates to determine the total buffer impacts for this portion of the North Pointe project. (Rev. 1) Figure 5 does not match Figure 6 with regard to the stream buffer disturbance around the culvert crossing. Figure 6 is correct. Also, the existing crossing should be excluded from the disturbed buffer calculations. The "South" disturbance area does not need to be mitigated because stormwater conveyance channels are permitted in the buffer with county approval per 17- 318.B.5 and 17- 318.C.6 Should "50,215sf" in Section 1.2 be "88,165sf "? This number would have to be updated based on issues raised earlier in this comment. (Rev. 2) Comment has been addressed. The plan shows the correct amount of linear streambank work and buffer plantings, summarized in Table 2, to mitigate for the disturbances proposed under ESC applications WPO- 2009 - 00061, WPO- 2009 - 00067, and WPO- 2010 - 00017. 2. The side slopes of the stream crossing cannot be counted towards the total mitigation area. [17- 320-D.5] Also, the ESC plan for this stream crossing has a proposed groundcover proposed for the side slopes to meet county requirements. The engineering division of the Community Development Department is concerned a proposed forested condition on the 2:1 slopes would experience more erosion than a woody groundcover. (Rev. 1) This area of the site has been removed from the proposed plan. 3. An Army Corps of Engineers permit will be required prior to construction for the stream restoration plans. If the applicant feels they do not need a permit for the proposed work, please provide confirmation from an Army Corps of Engineer representative after submitting this package Albemarle County Community Development Engineering Review Comments Page 2 of 3 to them. (Rev. 1) When it is received, please forward Army Corps approval of the streambank work as described on page 31 of the report. (Rev. 2) Army Corps approval for the streamwork has not yet been approved. The mitigation plan cannot be completely approved by the county until the application to the Army Corps is acceptable to them. 4. Please provide a table summarizing proposed buffer impacts and proposed mitigation areas (including the stream restoration equivalency outlined in the design manual). Considering the increased impacts as identified in comment 1 and the prohibition of using the road side slopes as called out in comment 2, it is our estimation that the total opportunities on site for mitigation will not be enough to meet the requirements. Engineering review will allow the plan to be approved short of the required 2:1 ratio if it appears that the applicant is providing mitigation in all other practicable areas. (However, if a County Mitigation bank is established before plan approval, the applicant will be required to pay into this bank for the mitigation that could not be provided on site.) Additional areas of possible mitigation include streamwork at the confluence of Flat Branch and the unnamed tributary north of the crossing (and other possible eroded banks north of the culvert), the removal of the pond embankment, and VDOT outlet stabilization along Flat Branch. (Rev. 1) On page 30 of the Mitigation Narrative, the design manual states that "I' of restored channel for every I00sf of disturbed area" is a mitigation option. This implies that every Ift linear feet of channel restoration is equivalent to 200sf of required planting. If the 12,000sf "North" section is not approved as part of the permanent stormwater management facility, it must be replanted. This replanted area can be counted towards total mitigation requirements. The county currently does not have a mitigation bank set up and cannot accept any payment for buffer disturbance. It appears as though the applicant has not exhausted all opportunities along Flat Branch. As noted in the County's Stream Assessment performed in 2003 and shown on page 29 of the narrative, there are erosion downstream of the roadway culvert. I expect there are ample opportunities from road culvert to the river. The county assessment notes bank erosion and buffer issues. The cross - sections on pages 33, 34, and 35 are not clear in Figure 23 and it is very difficult to decipher where along the stream which cuts are proposed. Two of these sections do not show any construction (streambank 2 and Streambank 3. If these designations correspond to Figure 23 then it appears that only 295ft of bank stream restoration is actually occurring. (Rev. 2) Comment has been addressed. The plan shows the correct amount of linear streambank work and buffer plantings, summarized in Table 2, to mitigate for the disturbances proposed under ESC applications WPO- 2009 - 00061, WPO- 2009 - 00067, and WPO- 2010 - 00017. Areas C and D appear to be isolated by steep slopes. Please detail how the areas are to be accessed in order to be bushhogged. If grading or clearing of forest or trees is necessary, the work will need to be included in the stream crossing ESC plan. (Rev. 1) Comment has not been addressed. (Rev. 2) It is still unclear how access to the planted areas (now A, B, and C) will be provided. This concern has been increased since the last submittal because much more streamwork has been added. The streamwork will require excess soil to be hauled away which will require new access roads from the stream to areas of the site already covered by ESC plans. Either this mitigation plan or the appropriate ESC plans should be modified to show how the necessary equipment can access the more remote areas of the mitigation work. The plan (or plans) that Albemarle County Community Development Engineering Review Comments Page 3 of 3 alleviates the access concerns should clearly state that existing buffer vegetation is to be preserved (except in Areas A, B, and C) as much as possible and that all haul roads should be protected with ESC measures where appropriate. If Area A is to be accessed from Area B, an appropriately size Stream Crossing should be detailed in the plan. It looks as though the work on the east side of the stream can be accessed by a graded roadbed that runs adjacent to the diversion dike and fill diversion on WPO- 2010 - 00017, which means the stream work must be performed before Phase II of this plan. The work on the west side of the stream appears to be accessible from the south end of the turn lane work of WPO- 2009 - 00067. 6. Please show the ESC measures, limits of disturbance, and replanting plan for the construction necessary to perform the stream channel restoration. For instance, how will the work within the existing forest be performed without damaging trees that must remain? I suspect there will need to be a temporary access road provided through the forest adjacent to the stream to haul away excess sediment. How will this road be cleared, protected from erosion, and replanted? (Rev. 1) Comment has not been addressed. Will the ESC plan be updated to include the mitigation work? (Rev. 2) Please refer to the previous comment. 7. The bond for the mitigation plantings will be computed at the time of plan approval. (Rev. 1) Comment remains unchanged. (Rev. 2) Comment remains unchanged. 8. (Rev. 2) Please provide the minimum specifications for the EC -2 matting to be used on the streambank. Some variations of EC -2 matting used for general ESC purposes may not be adequate for the stream bank stabilization. E3_mp_PBC_North Pointe Stream Crossing_wpo200900061.doc