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HomeMy WebLinkAbout189-08 RESOLUTIONRESOLUTION NO. 189-08 A RESOLUTION TO APPROVE A REQUEST TO MODIFY AND REPLANT A PORTION OF THE TREE PRESERVATION AREA ASSOCIATED WITH HILL PLACE PZD, IN ORDER TO INSTALL A VEHICULAR BRIDGE ACROSS COLLEGE BRANCH CREEK. WHEREAS, as required with the approved Hill Place Planned Zoning District, a vehicular bridge is to be constructed across the creek and established tree preservation area; and WHEREAS, to accomplish the bridge installation, a portion of the tree preservation area will be impacted and subsequently the riparian corridor replanted; NOW, THEREFORE, BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF FAYETTEVILLE, ARKANSAS: Section 1: That the City Council of the City of Fayetteville, Arkansas, pursuant to UDC Chapter 167 (L)(2), hereby approves a resolution to permit the described construction within the tree preservation area associated with the bridge installation, with the following conditions: 1) All construction activities, including installation of erosion control and tree protection fencing, shall be permitted and inspected by both the City Engineering office and the Urban Forester prior to commencement. 2) On-site mitigation will be required to replace the 2,100 square feet of canopy lost. Mitigation will require ten (10) 2 -inch caliper large species trees to be located in the reclamation area. 3) All mitigation trees shall be native and represent species currently established and appropriate within the creek riparian area. The exact species will be determined at the time of planting and approved by the Urban Forester. 4) Planting shall occur with the completion bridge installation, to assist in erosion control and re-establishing the creek bank. 5) All mitigation trees shall be guaranteed by bond, letter of credit or cash deposit with the City for three years. The bond shall cover plant material, installation and three years of maintenance. PASSED and APPROVED this 7th day of October, 2008. �O kK/TR APPROVED: ATTEST: _ c e FAYETTEVILLE By: RkANSP�.- By: y: ,tom n 1 tYititA(_ �iGp DAN OODY, Mayor SONDRA E. SMITH, City ClerWTreasurer '��,,, ryG 6N City of Fayetteville Staff Review Form City Council Agenda Items and Contracts, Leases or Agreements 9/16/2008 City Council Meeting Date Agenda Items Only Jeremy Pate Y Planning Operations Submitted By Division Department Action Required: ADM 08-3093: (Hill Place Culvert Removal): Submitted by Appian Centre for Design, requesting modification and replanting of a portion of the Tree Preservation Area associated with Hill Place PZD, in order to remove an existing culvert located within College Branch Creek to reduce flood levels and to install the required vehicular bridge spanning the creek. Cost of this request Account Number Project Number Budgeted Item Department City Finance and Internal Service Director Category / Project Budget Funds Used to Dale Remaining Balance Budget Adjustment Attached Program Category / Project Name Program / Project Category Name Fund Name Previous Ordinance or Resolution # Original Contract Date: Original Contract Number: Date Received in City ^24-07 Clerk's Office F�.�ol Date Received in Mayor's Office Date Revised §ril 16, 20`0J ZOO City Council Meeting of September 16, 2008 Agenda Item Number CITY COUNCIL AGENDA MEMO To: Mayor and City Council Thru: Gary Dumas, Director of Operations From: Jeremy C. Pate, Director of Current Planning* Date: August 26, 2008 Subject: Hill Place Culvert Removal from College Branch Creek (ADM 08-3093) RECOMMENDATION In accordance with the recommendations by the Engineering Staff and the City's Urban Forester (see attached memos), staff recommends approval of a resolution to permit the removal an existing, unpermitted 10 -foot diameter culvert from College Branch Creek within the limits of the Hill Place project. This action will also permit the property owner to remove unhealthy and invasive species of shrubs and trees within the identified construction area, restore the health of several trees in decline, replant this area with new trees, and add erosion control measures to prevent future and continued erosion in conjunction with the culvert removal and vehicular bridge installation. BACKGROUND A 10 -foot diameter culvert was placed within College Branch Creek in the late 1980s, near the railroad. In discussions with Engineering staff and the Urban Forester, the applicant has proposed to remove this culvert, at the developer's cost, in order to reduce the current flood levels along the creek. The culvert removal is not required by the City, yet will aid in reducing erosion potential and flood levels along the creek. The culvert currently creates "headwater flooding" due to a lack of capacity in size for storm events larger than a five-year flood. According to the Engineering Division, the culvert is a restriction to the existing creek and could not be permitted in accordance with today's Corps of Engineers regulations. A HEC -RAS hydraulic model was provided to staff, which indicates that removal of the 10 ft culvert and embankment will reduce the depth of flooding upstream, and will have no detrimental impact downstream. Rather, as the attached photos indicate, the existing culvert is beginning to structurally fail, as it was not designed for its intended use. In the event the culvert fails, or is overtopped, the embankment will be eroded and washed downstream which could cause detrimental environmental impact to property owners. Removal with the development of Hill Place PZD, by the developer, will eliminate this potential altogether. In addition, as required with the Hill Place PZD, a vehicular bridge will cross the creek in place of the existing pedestrian bridge, to provide a second means of access. As anticipated when the PZD was submitted and approved, this bridge will span the creek's floodplain, but will also likely result in theremoval of some small trees in this area that are required to be mitigated. City Council Meeting of September 16, 2008 Agenda Item Number Because the culvert and bridge crossing are within the established Tree Preservation Area, and a small amount of clearing will need to occur to access and remove the culvert and install the bridge, City Council approval is required. The Tree Preservation and Protection Code, Chapter 167(L)(2) of the UDC states: The geographic extent and location of tree preservation areas, once recorded, may only be modified, or abolished with the express approval of the City Council Applicants requesting such action shall bear the burden of proving to the City Council's satisfaction that such modification or abolition is in the best interest of the City of Fayetteville. Such requests shall be submitted to the landscape administrator [urban forester], who shall ask the city clerk to place it on the agenda of the next regularly scheduled City Council meeting. While the request will not modify or abolish the extent and location of the tree preservation area, some tree removal will be required to accomplish the two objectives stated herein. A property owner is permitted to remove dead or diseased trees within a Tree Preservation Area without Council approval, but not live or healthy trees. The Urban Forester has reviewed the request and a proposed mitigation plan. Approximately 13,634 ftz of canopy within the Tree Preservation Area will be affected by the culvert removal and re -grading of the bank, and 2,100 ft2 with the installation of the vehicular bridge. The trees in this area are mostly volunteers which germinated at some point after the culvert was installed. No significant trees and only one larger tree will be removed, with an additional large invasive tree that will be removed. This area also has less desirable species, vines and underbrush. Staff recommends City Council approval of this modification of an existing Tree Presevation Area to accomodate the bridge enlargement and the culvert removal as no net loss of Tree Presevation Area will occur once mitigation trees are planted. This is due to the higher replacement rate used to calculate tree mitigation. Based on this calculation, the applicant will be required to replant 55 2 -inch caliper trees within the riparian corridor. In addition, staff has recommended conditions, based on the applicant's request, to plant back native species in this area and to re-establish a healthy riparian corridor. This request would result in the removal and mitigation for 15,734 sq. ft. of canopy removed. All mitigation trees are required to be bonded 'for a three-year period. BUDGETIMPACT 1►N"M RESOLUTION NO. A RESOLUTION TO APPROVE A REQUEST TO MODIFY AND REPLANT A PORTION OF THE TREE PRESERVATION AREA ASSOCIATED WITH HILL PLACE PZD, IN ORDER TO REMOVE A CULVERT WITHIN COLLEGE BRANCH CREEK AND TO INSTALL A VEHICULAR BRIDGE, AS DESCRIBED HEREIN. WHEREAS, the applicant has studied an existing, un -permitted 10 -foot diameter culvert located within College Branch Creek, which contributes to erosion and increased flooding; and WHEREAS, removal of the structurally failing culvert would reduce flooding potential upstream and reduce the likelihood of detrimental erosion impacts downstream; and WHEREAS, as required with the approved Hill Place Planned Zoning District, a vehicular bridge is to be constructed across the creek and established Tree Preservation Area; and WHEREAS, to accomplish ,the described culvert removal and bridge installation, a portion of the Tree Preservation Area will be impacted and subsequently the riparian corridor replanted; NOW, THEREFORE; BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF FAYETTEVILLE, ARKANSAS: Section 1: That the City Council of the City of Fayetteville, Arkansas, pursuant to UDC Chapter 167 (L)(2), hereby approves a resolution to permit the described construction within the Tree Preservation Area associated with the bridge installation and culvert removal, with the following conditions: 1) All construction activities, including installation of erosion control and tree protection fencing, shall be permitted and inspected by both the City Engineering office and the Urban Forester prior to commencement. 2) Where feasible, native species that are to be removed shall be tree spaded, healed in and watered, and transplanted back to the site after construction. 3) On-site mitigation will be required to replace the 15,734 square feet of canopy lost. Mitigation will require 55 (2) inch caliper large species trees to be located in the reclamation area. 4) All mitigation trees shall be native and represent species currently established and appropriate within the creek riparian area. The exact species will be determined at the time of planting and approved by the Urban Forester. 5) Planting shall occur with completion of the culvert removal and bridge installation, and bank grading to assist in erosion control and re-establishing the creek bank. 6) All mitigation trees shall be guaranteed by bond, letter of credit or cash deposit with the City for three years. The bond shall cover plant material, installation and three years of maintenance. PASSED and APPROVED this _ day of 2008. APPROVED: K.WR COUNCII. AGENDA REQUESTS@008 Agenda Rcquesls\18-gcptanba 16, 3008\ADM (08-3093 (Hill Place Culven Removal) RES &c 2 TayeLL ARKANSAS THE CITY OF FAYETTEVILLE, ARKANSAS 113 W. Mountain St. Fayetteville, AR 72701 PARKS AND RECREATION DIVISION CORRESPONDENCE Telephone: (479) 444-3470 To: Mayor Dan Coody and City Council From: Greg Howe, Urban Forester Date: August 28, 20o8 Subject: Modification and Replanting of the Tree Preservation Area for Hill Place STAFF REPORT DEVELOPMENT REQUEST/BACKGROUND The engineering agent, Appian Center for Design (ACD) for the Hill Place Development has presented information to the City's Engineering Department which indicates that an un -permitted culvert in College Branch Creek is undersized and raises the flooding potential along 6th St. The City Engineering Department agrees that removing this culvert could improve flow in the creek during periods of heavy rainfall or snow melt. ACD has requested to remove this culvert as part of the Hill Place Development construction. The culvert, creek and it's riparian buffer are within an area already established as a Tree Presevation Area. To accomplish the culvert removal small trees and brush in the Tree Preservation Area will need to be removed and the bank graded back to the natural grade of the creek In addition to the culvert removal, to meet transportation and engineering requirements, ACD proposes to enlarge the vehicular bridge spanning the creek and the Tree Protection Area. They also will have to install a drainage spillway from the bridge into the creek. In order to gain approval of this request, ACD, on behalf of the developers, has agreed to mitigate the tree loss at a higher rate than required based on the condition of trees being removed. FINDINGS -The Tree Preservation Area (TPA) encompasses 162,478.8 ft2 and is located on either side of College Branch Creek for the entire length of this development. Approximately 13,634 ftz or 8.4% of the TPA will be affected by the culvert removal and re -grading of the bank. The trees in this area are mostly volunteers which germinated at some point after the culvert was installed. No significant trees and only one larger tree will be removed. This area also has some less desirable species, vines and underbrush. -The Tree Presevation Area to be affected by the expansion of the vehicluar bridge and drainage spillway is 2,100 ftz or 1.3% of the TPA. Only a few smaller trees and one large invasive species tree will need to be removed. RECOMMENDATION Staff recommends City Council approval of this modification of an existing Tree Preservation Area to accomodate the bridge enlargement, drainage spillway and the. culvert removal as no net loss of Tree Preservation Area will occur once mitigation trees are planted. This is due to the higher replacement rate used to calculate tree mitigation. The following conditions must be met: 1. The Urban Forester encourages where economically feasible to tree spade existing trees, especially some of the cedars, heal in and water, then transplant back to the site after construction 2. On-site mitigation will be required to replace the 15,734 square feet of canopy lost. Mitigation will require 55 (2) inch caliper large species trees be located in the culvert reclamation area. 3. All mitigation trees shall be native and represent species currently established within the creek riparian area. The exact species will be determined at time of planting and approved by the Urban Forester. 4. Planting shall occur with completion of the culvert removal and bank grading to assist in erosion control and re-establishing the creek bank. Supplemental irrigation shall be provided as needed to guarantee survivial. 5. All mitigition trees shall be guarateed by bond, letter of creditor cash deposit with the City for 3 years. The bond shall cover plant material and 3 years of maintenance. FAYETTEVILLE THE CITY OF FAVETTEVILLE, ARKANSAS 113 W. Mountain St. Fayetteville, AR 72701 Telephone: 479-575-8206 ENGINEERING DIVISION CORRESPONDENCE TO: City Council Members FROM: Glenn E. Newman, Jr., P.E., Staff Engineer DATE: August 27, 2008 SUBJECT: Hill Place — Culvert Removal from College Branch Creek Place Properties has proposed the removal of the existing 10 ft diameter culvert and embankment crossing College Branch Creek within the limits of the Hill Place project. The existing culvert is a restriction to the natural creek and, if placed today, would not meet the Corp of Engineers "No Rise' requirement. The 100 yr storm event water surface elevation increase due to the existing culvert is over 11 ft. The existing culvert is not required for the proposed development, nor was it included in the design. A pedestrian bridge as part of the Tsa-La-Gi Trail System will be constructed by the City (at a later date) and a two way vehicular bridge with a sidewalk one side is proposed by the development. Based on the HEC -RAS hydraulic model provided, removal of the existing 10 ft culvert and embankment has no adverse affect on the downstream property owners and will reduce the depth of flooding upstream. (Approximately 9 inches at 6th street) See the attached spreadsheet for specifics. Photographs provided also indicate the culvert is beginning to structurally fail. In the event the culvert fails, or is overtopped, the embankment will be eroded and washed downstream which could cause adverse environmental affects. The Engineering Department recommends approving the removal of the existing culvert and associated embankment for the reasons stated above. Hill Place - Final Drainage Report (Rev -3) COMPARISON OF HILL PLACE PROJECT WITH AND WITHOUT 10' CULVERT BRIDGE, NO CULVERT BRIDGE, CULVERT STATION 100 -YEAR WSE 100 -YEAR WSE CHANGE 6TH ST 2819 1256.71. 1257.48 1900 1243.11 1250 1800 1240.29 1249.94 1700 1238.64 1249.95 10' CULVERT 1600 1236.2 1236.2 1550 1236.66 1236.66 1500 1236.26 1236.26 1450 1235.65 1235.65 1400 1235.72 1235.72 1300 1235.52 1235.52 1250 1234.92 1234.92 1200 1235.92. 1234.92 1150 1234.49 1234.49 1100 1234.05 1234.05 1061 1234.32 1234.32 NEW BRIDGE 1028 1233.31 1233.31 1000 1233.34 1233.34 950 1233.45 1233.45 900 1232.12 1232.12 850 1232.05 1232.05 800 1232.12 1232.12 DS PROP. LINE 750 1230.74 1230.74 700 1230.17 1230.17 650 1230.18 1230.18 600 1230.27 1230.27 500 1229.06 1229:06 400 1228.48 1228.48 300 1228.18 1228.18 11TH ST 256 1228.1 1228.1 200 1226.2 1226.2 100 1225.99 1225.99 0.77 6.89 9.65 11.31 u p 5+ mea r,A; 0 0 0 0 0 0 -1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 bowrs-treAw,, DESIGN CONCEPT LID techniques will be utilized to disconnect impervious surfaces and slow the velocity of urban runoff from the project by utilizing small-scale features such as bioswales, raingardens, and depressed parking lot islands to maximize capture of stormwater runoff and impede flow. Existing retention ponds will be utilized with some modifications. ---- -- - - .- - _._ ..- .I.4/" .a �r/1,I/I.'Y/.'I' x A A Vi \ / _. ---- 08 c GG ® 13 GO F 15 ir GO 17GO < ❑ 18 18 Go © Go zt 1 c 0 CO c zs GO O 18 E C GO Y \ ,eB GRADIN, eCONVERT CURB INLET TO . 70 SECTION; POUR NEW TOP ELEVATION SHOWN. eCONVERT GRATE INLET TO 7T GRATE; POUR NEW TOP W7 SHOWN. 73 CUT 6_ X 24" OPENING IN eEXISTING INLET IS PARTIAL 74 NOT YET BEEN CONSTUCTE GN EXISTING INLET IS PARTIAL 75 NOT YET BEEN CONSTRU( / "= 30 I Scale GSrNo.1�9�9�c O /N E. PO TUU Z51� P L 7w C APP1ANoNC ENwl E. DICKEIST. SUITE I .` PH# 14791 442-14A DATE:B/25/06 CONSTRUCTIC j DOCUMENT! GRADING PLAN F SHEET B SCALE: 1"=301 PAGE 19 or 63 - r A . ©2005 CD REVISION 5 r M CENTRE FOR DESIGN [AHOSCAPE ARCHITECTHRE I PLANNING I CIVIL ENGINEERING July 16, 2008 City of Fayetteville 113 W. Mountain Fayetteville, AR 72701 Attention: Mr. Pate RE: Hill Place Property removal of the 10 -foot culvert along College Branch Mr. Pate, Place Properties and Appian Centre for Design would like to remove an existing ten -foot metal corrugated culvert to allow College Branch Stream to return to its natural character and reduce the 100 -year flooding of College Branch above the culvert. Sometime between 1986 and 1990, a ten -foot diameter corrugated metal culvert was placed in College Branch Creek on the west side of the Hill Place property, near the railroad. The culvert and the trees currently lie within a dedicated tree easement administered by the City of Fayetteville. Currently, the culvert creates headwater flooding due to a lack of capacity for storm events larger than a five- year flow. This headwater flooding interferes with the flow from the railroad tunnel culvert under the railroad directly upstream, exacerbating a flooding problem along Sixth Street While removal of the culvert will not correct the problem along Sixth Street, it will lower the flood elevations. Currently, there is some young, low -quality vegetation growing on the slopes near each end of the culvert There are no significant trees per the City of Fayetteville landscape Manual that would need to be removed. There is also some erosion and invasive shrub species around the culvert that would also be removed. Appian plans to restore natural functions and features to lessen the impact of the environment on the stream and recreate its original character. River rock will be laid along the stream bed, or toe zone, to prevent the strearn bed's erosion and carry low-level water flows. The splash zone that will carry the primary flooding will be planted with hardy grasses and submergent vegetation, along with placement of large rocks and boulders to prevent erosion. The bank zone, often referred to as the stream's overbank, will be planted with small tees, shrubs and native groundcover to create microclimates and stabilize the upper stream. The terrace zone is the area where the strearn bank begins to return to its normal character. Here, trees, shrubs, and herbaceous plants will be used not only to create microclimates for plants and animals but to lower the water temperature and increase its capacity to hold oxygen needed by aquatic plants and animals. In summary, by removing the culvert and restoring the stream back to its natural state the 100 -year rainfall event will be prevented from swelling its banks immediately upstream and will also lower the 100 -year flooding beyond the railroad tracks. We appreciate your consideration in this matter. Attached are exhibits to help further understand the situation. Respectful] us[in Rowser, P.E. Design Team leader Appian Centre for Design I ._I _,_I .� Tayewevl ARKANSAS THE CITY OF FAYETTEVILLE, ARKANSAS PLANNING DIVISION CORRESPONDENCE 125 W. Mountain St. Fayetteville, AR 72701 Telephone: (479) 575-8267 To: City Council, Mayor Dan Coody From: Jeremy Pate, Director of Current Planning Date: 29 September 2008 Subject: ADM 08-3093 Hill Place Culvert Removal and Bridge Installation The applicant for this item has withdrawn the request to remove and mitigate for tree canopy within the Hill Place tree preservation area associated with the proposed removal of the existing 10 -foot diameter steel pipe culvert within College Branch Creek. The culvert will remain in place, unless the City chooses to remove it at a later date, at which time Place Properties will fully cooperate. A letter is attached. The request to remove and mitigate for tree canopy for installation of the vehicular bridge, replacing the pedestrian bridge across the creek, is still applicable and relevant to the conditions of approval placed upon the project by the City Council. As discussed when the PZD was approved, the applicants are required to install a new bridge across the creek linking the project. Associated with this removal is a minimum amount of tree canopy disturbance (2100 square feet) within the tree preservation area, necessary for the construction and installation of the bridge. All canopy within this area will be mitigated, and is subject to approval by the Urban Forester. Staff recommends the Council amend the Resolution to reflect the attached language. K-Ueremy12008 CorrespondencelBoard MemasUDM 08-3093 Hill Place Culvert Removal.doc RESOLUTION NO. A RESOLUTION TO APPROVE A REQUEST TO MODIFY AND REPLANT A PORTION OF THE TREE PRESERVATION AREA ASSOCIATED WITH HILL PLACE PZD, IN ORDER TO INSTALL A VEHICULAR BRIDGE ACROSS COLLEGE BRANCH CREEK. WHEREAS, as required with the approved Hill Place Planned Zoning District, a vehicular bridge is to be constructed across the creek and established tree preservation area; and WHEREAS, to accomplish the bridge installation, a portion of the tree preservation area will be impacted and subsequently the riparian corridor replanted; NOW, THEREFORE, BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF FAYETTEVILLE, ARKANSAS: Section 1: That the City Council of the City of Fayetteville, Arkansas, pursuant to UDC Chapter 167 (L)(2), hereby approves a resolution to permit the described construction within the tree preservation area associated with the bridge installation, with the following conditions: I) All construction activities, including installation of erosion control and tree protection fencing, shall be permitted and inspected by both the City Engineering office and the Urban Forester prior to commencement. 2) On-site mitigation will be required to replace the 2,100 square feet of canopy lost. Mitigation will require ten (10) 2 -inch caliper large species trees to be located in the reclamation area. 3) All mitigation trees shall be native and represent species currently established and appropriate within the creek riparian area. The exact species will be determined at the time of planting and approved by the Urban Forester. 4) Planting shall occur with the completion bridge installation, to assist in erosion control and re-establishing the creek bank. 5) All mitigation trees shall be guaranteed by bond, letter of credit or cash deposit with the City for three years. The bond shall cover plant material, installation and three years of maintenance. PASSED and APPROVED this _ day of , 2008. APPROVED: September 19, 2008 City of Fayetteville 113 W. Mountain Fayetteville, AR 72701 Attention: Jeremy Pate RE: Hill Place Culvert Removal Dear Mr. Pate: Following the tabling of our request to remove the 10' steel pipe culvert from College Branch Creek on the Hill Place project at the City Council meeting on September 16, 2008, we have decided to withdraw our request to remove the culvert This is obviously a very controversial and politically driven issue, and, while we believe it is the most appropriate action for the protection and restoration of College Branch Creek, Place Properties has decided it best for the City of Fayetteville to properly administer the tree pnservationeasementas they see fit. From an engineering perspective, we do believe there is a need to remove the culvert. -We -believe that we have sufficiently notified the City of Fayetteville of the hazard that exists with the culvert remaining in the creek, and if the City of Fayetteville deems it necessary to remove the culvert from the dedicated tree preservation easement in the future utilizing City of Fayetteville resources, the City of Fayetteville will receive full cooperation from Place Properties. We do, however, request that the City of Fayetteville continue to consider our request to place the new vehicular bridge within the tree preservation easement at the next scheduled City Council meeting. If you require revised tree preservation calculations, please do not hesitate to contact me. Thank you for your consideration of this matter. Respectfully, '-- A in E. Rowser, P.E. Design Team Leader Appian Centre for Design cc: Ron Petrie, P.E., City Engineer Greg Cislo, Place Properties Greg Howe, Urban Forester Appian Centre for Design • 217 East Dickson Street • Sade 104 - Fayetteville, AR 72701 • phare (479) 442-1444 • fax (479) 442-1450 City Council Meeting of September 16, 2008 Agenda Item Number CITY COUNCIL AGENDA MEMO Mayor and City Council Thru: Gary Dumas, Director of Operations From: Jeremy C. Pate, Director of Current Planning* August 26, 2008 Subject: Hill Place Culvert Removal from College Branch Creek (ADM 08-3093) RECOMMENDATION In accordance with the recommendations by the Engineering Staff and the City's Urban Forester (see attached memos), staff recommends approval of a resolution to permit the removal an existing, unpermitted 10 -foot diameter culvert from College Branch Creek within the limits of the Hill Place project. This action will also permit the property owner to remove unhealthy and invasive species of shrubs and trees within the identified construction area, restore the health of several trees in decline, replant this area with new trees, and add erosion control measures to prevent firture and continued erosion in conjunction with the culvert removal and vehicular bridge installation. BACKGROUND A 10 -foot diameter culvert was placed within College Branch Creek in the late 1980s, near the railroad. In discussions with Engineering staff and the Urban Forester, the applicant has proposed to remove this culvert, at the developer's cost, in order to reduce the current flood levels along the creek. The culvert removal is not required by the City, yet will aid in reducing erosion potential and flood levels along the creek. The culvert currently creates "headwater flooding" due to a lack of capacity in size for storm events larger than a five-year flood. According to the Engineering Division, the culvert is a restriction to the existing creek and could not be permitted in accordance with today's Corps of Engineers regulations. A HEC -RAS hydraulic model was provided to staff, which indicates that removal of the 10 It culvert and embankment will reduce the depth of flooding upstream, and will have no detrimental impact downstream. Rather, as the attached photos indicate, the existing culvert is beginning to structurally fail, as it was not designed for its intended use. In the event the culvert faits, or is overtopped, the embankment will be eroded and washed downstream which could cause detrimental environmental impact to property owners. Removal with the development of Hill Place PZD, by the developer, will eliminate this potential altogether. In addition, as required with the Hill Place PZD, a vehicular bridge will cross the creek in place of the existing pedestrian bridge, to provide a second means of access. As anticipated when the PZD was submitted and approved, this bridge will span the creek's floodplain, but will also likely result in the removal of some small trees in this area that are required to be mitigated. City Council Meeting of September' 16, 2008 Agenda Item Number Because the culvert and bridge crossing. are within the established Tree Preservation ., 1 Area, and a small amount of clearing will need to occur to access and remove the culvert and install the bridge, City Council approval is required. The Tree Preservation and Protection Code, Chapter 167(L)(2) of the UDC states: The geographic extent and location of tree preservation areas, once recorded, may only be modified, or abolished with the express approval of the City Council Applicants requesting such action shall bear the burden of proving to the City Council's satisfaction that such modification or abolition is in the best interest of the City of Fayetteville. Such requests shall be submitted to the landscape administrator [urban forester), who shall ask the city clerk to place it on the agenda of the next regularly scheduled City Council meeting.. -While the request will not modify or abolish the extent and location of the tree preservation area, some tree removal will be required to accomplish the two objectives stated herein. A property owner is permitted to remove dead or diseased trees within a Tree Preservation Area without Council approval, but not live or healthy trees. The Urban Forester has reviewed the request and a proposed mitigation plan. Approximately 13,634 ftz of canopy within the Tree Preservation Area will be affected by the culvert removal and re -grading of the bank, and 2,100 ft with the installation of the vehicular bridge. The trees in this area are mostly volunteers which germinated at some point after the culvert was installed. No significant trees and only one larger tree will be removed, with an additional large invasive tree that will be removed. This area also has less desirable species, vines and underbrush_ Staff recommends City Council approval of this modification of an existing Tree Presevation Area to accomodate the bridge enlargement and the culvert removal as no net loss of Tree Presevation Area will occur once mitigation trees are planted. This is due to the higher replacement rate used to calculate tree mitigation. Based on this calculation, the applicant will be required to replant 55 2 -inch caliper trees within the riparian corridor. In addition, staff has recommended conditions, based on the applicant's request, to plant back native species in this area and to re-establish a healthy riparian corridor. DISCUSSION This request would result in the removal and mitigation for. 15,734 sq. ft. of canopy removed. All mitigation trees are required to be bonded 'for a three-year period. BUDGETIMPACT None. RESOLUTION NO. A RESOLUTION TO APPROVE A REQUEST TO. MODIFY AND REPLANT A PORTION OF THE TREE PRESERVATION AREA ASSOCIATED WITH HILL PLACE PZD, IN ORDER 1'0 REMOVE A CULVERT WITHIN COLLEGE BRANCH CREEK AND TO INSTALL A VEHICULAR BRIDGE, AS DESCRIBED HEREIN. WHEREAS, the applicant has studied an existing, un -permitted 10 -foot diameter culvert located within College Branch Creek, which contributes to erosion and increased flooding; and WHEREAS, removal of the structurally failing culvert would reduce flooding potential upstream and reduce the likelihood of detrimental erosion impacts downstream; and WHEREAS, as required with the approved Hill Place Planned Zoning District, a vehicular bridge is to be constructed across the creek and established Tree Preservation Area; and WHEREAS, to. accomplish= -the described culvert removal and bridge installation, a portion of the Tree Preservation Area will be impacted and subsequently the riparian corridor replanted; NOW, THEREFORE BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF FAYETTEVILLE; ARKANSAS: Section 1: That the City Council of the City of Fayetteville, Arkansas, pursuant to UDC Chapter 167 (L)(2), hereby approves a resolution to permit the described construction within the Tree Preservation Area associated with the bridge installation and culvert removal, with the following conditions: l) All construction activities, including installation of erosion control and tree protection fencing, shall be permitted and inspected by both the City Engineering office and the Urban Forester prior to commencement. 2) Where feasible, native species that are to be removed shall be tree spaded, healed in and watered, and transplanted back to the site after construction. 3) On-site mitigation will be required to replace the 15,734 square feet of canopy lost. Mitigation will require 55 (2) inch caliper large species trees to be located in the reclamation area. 4) All mitigation trees shall be native and represent species currently established and appropriate within the creek riparian area. The exact species will be determined at the time of planting and approved by the Urban Forester. y 5) Planting shall occur with completion of the culvert removal and bridge installation, and bank grading to assist in erosion control and re-establishing the creek bank. ) 6) All mitigation trees shall be guaranteed by bond, letter of credit or cash deposit with the City for three years. The bond shall cover plant material, installation and three Years of maintenance. PASSED and APPROVED this _ day of 2008. APPROVED: KACR COU M AGENDA REQUESiS't00II 2 10.14.08 Clarice Pearman - Res. 189-08 Page 1 From: Clarice Pearman To: Pate, Jeremy Date: 10.14.08 4:22 PM Subject: Res. 189-08 Attachments: 189-08 ADM 08-3093 Hill Place PZD.pdf CC: Audit Jeremy: Attached is a copy of the above resolution passed by the City Council regarding Hill Place PZD modifications. Please let me know if there is anything else needed for this item. If you have any questions please call don't hesitate to call me. Have a good day. Thanks. Clarice • lig �♦ v \ � ��s: 1Pp v \_ t �.< F i fi ��r 1 - •� LyJ :, • - .- ala• ' r Bei �• JL 1 t •fit �' �' ' o i rr sk Vo - Is wz I At �'•-• f 'i . 'Fx Y ... j1v, If f s, • X . 's' y] ,51 � a � � t'�.P �^,�` . } \�j�, a {:_ ; fS�. ♦' �. t ��S�i•, IV rrr j♦ 1R3'r i.tf' �v _ v .� �[. r t R y) ai ` Ric. } i�• K s - 'i i � r Yh. ..;'t � ' r +'r,. `,'•.. � ,. 'r .fit • •r ;--"'y'','�`. 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