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Agenda Item - 1992-09-15 TO: Development Review Board cuo����� • FROM: Natural Resources Commission SUBJECT: Moore Property Development Application PD 2-92/VAR 6-92 "rte DATE: September 15, 1992 The Natural Resources Commission (NRC).is providing the Development Review Board with recommendations regarding this proposed development because the site is a prime open space area with very high natural resource values. Our intent is to support the DRB in its review and decision-making capacity and to ensure that the existing natural features and processes remain intact. Our recommendations focus on the following areas: • 1. Making the proposed wetland mitigation in Bryant Nature Park functional, 2. Minimizing the effects of widening Childs Road on the adjacent wetlands, 3. Maintaining water quality within the on-site wetland, 4. Retaining the existing wildlife corridor along Canal Road, and 5. Minimizing tree and habitat damage and removal. As designed,the proposed development would have severe negative impacts on these existing natural resources. The NRC's recommendations are intended to lead to solutions that could make the development more compatible with the natural resource value of the site. I. Overview of Natural Resource Values of the Site • The site of the proposed development (Site) and the adjacent Bryant Nature Park (Park)were once a single large wetland surrounded by wooded upland habitat. The >tct : construction of Childs Road bisected this wetland and altered its drainage pattern. �.�..: In spite of this alteration, both the Site and the Park currently retain very high values as wetlands and wildlife habitat. T, • 4 Natural Resources Commission r C crC • In the City's recently completed Natural Resources Inventory, professional biolo- gists ranked the Park highest of any wildlife habitat in the Lake Oswego planning • area. The Site received only a slightly lower score because it does not have year- round flowing water and ponds as the Park does. The Park and the Site form one of the finest and largest natural areas within the City, providing food and shelter for a variety of birds, deer, ducks, frogs and other animals. • The Site, together with the Oswego Canal, provide an access corridor to the Tualatin River for the wildlife that utilize Bryant Nature Park. • The NRC previously assigned the Site a very high ranking as potential open space and requested the City Council seek to purchase the entire site. The Council concurred and directed the Trust for Public Lands to enter into purchase negotia- tions. A purchase agreement could not be reached. • The Site has also been identified in the METRO Greenspaces program as having regional significance. Should the proposed regional open space bond pass,the Site would again be a high priority for acquisition. The Greenspaces plan envisions the Site and Park as the anchor for a trail linking the Tualatin, Cooke's Butte, Luscher • Farm, and the Willamette River greenway. The NRC regrets losing the Site as an undeveloped natural area. We are concerned that any development be carefully designed and built,with sensitivity to its special qualities. II. Recommendations 1. REVISE PROPOSED WETLANDS MITIGATION IN BRYANT NATURE PARK As required by state and federal regulations, the applicant proposes to mitigate for the loss of wetlands resulting from improving Canal Road and widening Childs Road. This mitigation is proposed to be the enhancement of some of the wetland area in the City- owned Bryant Nature Park. A conceptual design of the proposed mitigation has been submitted as part of the development proposal. ID Natural Resources Commission 2 f • The NRC concurs that it is appropriate to locate the mitigation off-site. The Site is already a healthy, functioning wetland. The proposed mitigation location in the Park is largely covered with reed canary grass, which does not provide high-value wildlife habitat and which will force out wetland.plants of higher habitat value. The NRC concurs that the grassy areas of Bryant Nature Park could be good candidates for enhancement of wetland functions and values, if properly designed and constructed. However, since the area of proposed mitigation is public property and a City Park which enjoys very high utilization by both public and wildlife, the NRC feels very strongly that the support and approval of the Parks and Recreation Commission be secured before accepting the developer's mitigation proposal. The NRC had only ten days to review the extensive documentation associated with this project, between the time the Staff report was made available and the originally scheduled date of the DRB hearing. As a result, we were not able to fully coordinate our review of the proposed mitigation with the Park with the Parks and Recreation Commission. There was, however, a very careful review and consideration by the NRC in which we received input from professionals who design, construct and maintain • wetland mitigation. It is our conclusion that the conceptual mitigation design for enhancing the wetland in Bryant Park is not viable as currently planned. We strongly recom- mend the following revisions to the proposal: 1. Ensure City control of mitigation. Because the mitigation site is public property and a highly valued City park, it is essential that the City have complete control over any proposed public improve- ments. The developer should deposit funds with the City to pay for any and all costs associated with any mitigation project required as a condition to this development application. The City should have the ability to select the contractor and see that the improvements to public property are carried out as designed. This is critical to proper construction of the enhancement of our public nature park. 2. Connect the water flow in the existing pond into the new pond to maintain . year-round flooding. Flooding will eliminate most of the reed canary grass, as well as expand the Natural Resources Commission 3 1 habitat for amphibians and ducks. Otherwise, the location will continue to dry out during summer, and the reed canary grass will remain. • 3. Locate trees to shade the south and west side of the pond. Rather than scattering them around the perimeter, place trees to create shade. Shading will help discourage reed canary grass. 4. Specify a shallow depth of the pond. The correct depth is necessary to encourage red-legged frogs and discourage bullfrogs, which are predators to red-legged frogs, and to discourage reed canary grass. 5. Specify the timing Qf the construction. It is essential to avoid disturbing frogs during breeding season. 6. Ensure that maintenance of the improvements is for at least two years beyond the expiration of the Division of State Lands wetland fill permit. Maintenance is necessary to ensure the successful establishment of the wetland enhancement and elimination of the reed canary grass. This could be • accomplished through a maintenance bond. 2. DEFINE CHILDS ROAD WIDENING AND PROTECT ADJACENT WETLANDS The applicant proposes to reduce the half-street improvements that normally would be required along Childs Road, to minimize the impact on the adjacent wetlands. The design proposes expansion of the road right-of-way into Park property. The pavement is to be widened 5 feet to create a walkway. The widening would be constructed on the north side of the road, in the existing wetland and springs. Any widening of Childs Road will both eliminate and potentially damage the adjacent wetlands. Evidently,the recommendation to widen the road on its north side is intended to minimize damage to trees, wetlands, and red-legged frog habitat. However, based upon our review of the developer's consultant reports, we do not feel there is enough information on the record to support that recommendation. Red-legged frogs have • `f. been observed on both sides of the road. There is an active spring very close to the Natural Resources Commission 4 • road on the north side. Since road widening on either side will have significant impacts on wetlands and potentially on park habitat we recommend that this issue be investigated further. Information needed to make an informed judgment about widening is missing or incomplete: 1. The Transportation Element of the Comprehensive Plan is currently under review by the Planning Commission. The Commission will recommend clas- sification of Childs Road as either a Major Collector or a Minor Arterial. If designated as a Minor Arterial, we understand that the road will have to be widened on both sides, which would apparently render moot the issue of which side to widen. The classification should be determined prior to any decision on widening one side of the road. 2. The north side of the road is located directly adjacent to Indian Spring (in the southwest corner of the Park). This spring is a major water source for the park • wetland. Even now, during one of the driest years on record, a plentiful supply of clear, cool water is flowing from the spring into the pond. Our concern is that road construction would affect the springs, possibly altering or degrading the flow. The application does not describe or map the hydrology of the spring, does not state how road widening would affect its flow, or how it would be protected. 3. It could not be determined from the information provided which side of the road provides the better habitat for red-legged frogs. Recommendations: 1. Do not widen Childs Road at this time. 2. Require the applicant to place funds in escrow equivalent to the cost of standard half-street improvements. These funds would be applied to the widening when the design is approved and it is constructed. Any excess would be refunded. 3. Require the applicant to do mapping and study of the adjacent wetlands (on both sides of the road) to provide adequate information regarding red legged frog Natural Resources Commission 5 habitat, wetland, springs location and hydrology. • 4. Allow NRC and PRC to review the design and supporting information. 5. Require a contractor selected by the City construct the improvements. 3. MAINTAIN WATER QUALITY WITHIN THE ON-SITE WETLAND The proposed development places streets and houses in the upland area, next to the wetland. The surface water runoff from rooftops, driveways and streets will contain pollutants,such as lawn and garden chemical residues and oil and gasoline. This runoff will have to flow into the wetland. The NRC has developed the following recommen- dations to protect the wetland from polluted runoff: A. Require rural section streets, B. Eliminate the proposed drainage detention pond in the existing wetland, • C. Provide a minimum 50 foot buffer, and D. Verify existence of underground storage tank and remove if necessary. A. Require Rural Section Streets The NRC strongly recommends rural section street design for this development. "Rural section" refers to uncurbed streets with grassy swales instead of curbs and gutters. Rural section streets will reduce impervious surfaces, allow rainwater to percolate into the soil, help clean pollutants in runoff, and allow more trees to be retained. Rural streets are essential to maintain water quality in the wetland. City staff has recommended against rural section streets in this development. The design proposes wide streets and cul-de-sacs with curbs and gutters. However, rural section streets are mandated by City Council policy,by the Surface Water Management Master Plan and by the Comprehensive Plan as follows: • Natural Resources Commission 6 • 1. City Council Policy At their meeting on September 1, the City Council directed staff to revise the design for widening Washington Court to replace curbs and gutters with grassy swales. The Council requested the change to bring the street design into conformance with the recommended practice in the City's recently adopted Surface Water Management Master Plan. 2. Surface Water Management (SWM) Master Plan The SWM Master Plan, which has been adopted by the City Council, analyzed various development densities and street designs in terms of their impact on surface water runoff and pollutants. The analysis concluded that, for single family residential development,rural section streets were the preferred alternative. The analysis estimated that rural section streets produce less than half the pollutant runoff of curbed streets. To meet pollution reduction goals mandated by the federal Environmental Quality Commission, the master plan assumes that at least half of the city's future home development will be built with rural section streets. • Table 6.3, taken from the SWM Master Plan, shows that"ditch"streets produce less than half the runoff and half the pollution of "curbed" streets. TABLE 6.3 EXISTING ANNUAL POLLUTANT LOADINGS CATEGORIES RUNOFF TOTAL SOLIDS TOTAL PHOSPHORUS ac-ft/acre lbs/acre mg/1 lbs/acre mg/I Single Family Residential 1 Ditch, Low Density 0.11 29 99 0.03 0.10 2 Ditch, Med Density 0.29 81 101 0.08 0.10 3 Curbed, Med Density 0.66 186 104 0.18 0.10 4 Curbed, High Density 1.00 278 102 0.27 0.10 In describing the benefits of grassy swales, the plan states"Grassy swales slow runoff and remove suspended pollution. Significant reduction in storm runoffs 110 and washoffs are possible relative to the traditional curb-and-gutter used to collect runoff' (p.ES-8). Natural Resources Commission 7 7 Rural section streets also reduce impermeable surface area, which cuts pollution. The SWM Master Plan states "Pollutants generally accumulate along • the roadside. Areas with more street per acre allow more pollution to accumulate and wash off. Areas with less street per acre have reduced pollution loads" (p.ES-8). 3. Comprehensive Plan. The Comprehensive Plan includes several specific policies which mandate rural section streets in developments on sensitive lands: Natural Resources Policy Element=Wetlands Policies These policies direct the city to"preserve the natural function of these(essential) wetlands and protect them from deterioration." Where development occurs adjacent to wetlands, these policies require the wetlands to be protected. General Policy II, Specific Policy 3.c., 3.d. and 4, (p. 51) These policies require that development: "Preserve the natural retention storage capacity of the land...", "Prevent discharge of pollutants onto the ground", and • "Establish a storm drainage program that will incorporate subsurface and surface retention wherever practical". Residential Site Design Policy Element A major objective of this element is to "encourage innovative site design which...protects open space and lowers development costs" (p.78). This element also states that"Residential streets should be designed to the minimum scale necessary to function in the specific location..." (p.73). General Policy 1, b. and e. (p.79) The City will require major development site designs to include: "Preservation of natural features compatible with structures and site", and "Drainage management compatible with natural hydrologic systems" . General Policy V, j. "The City will make every reasonable effort to assist and support innovative design", including "drainage management or retention". • Natural Resources Commission 8 I • The proposed street design clearly violates the City's adopted policies on wetland protection, surface water management and residential site design. B. Eliminate proposed drainage detention pond in the existing wetland The development proposes to place a berm across the arm of the wetland that lies between lots 7-13 and 45-50, in order to create a detention pond. Storm sewers would channel runoff from the streets into the detention pond (See Exhibit 10, Utility Plan, and Exhibit 43, Water Quality and Detention Requirements, Basin Map). The purpose of this pond is to remove pollutants, but it proposessacrificing part of the existing healthy wetland to accomplish this. It is the NRC's position that pollutants must be removed with pollution control devices before the runoff reaches the wetland. It is not acceptable to pollute the existing wetland. The removal of pollutants should start with a design that reduces impermeable surfaces to a minimum. Street and cul-de-sac width should be reduced, and curbs and gutters replaced with grassy swales as outlined above. Upland trees and plants should be retained. These measures would reduce the pollutants in storm water runoff, and allow it to percolate into the soil. Any detention areas should be located in the uplands. Detention areas are designed to hold runoff temporarily, allowing sediments to settle out. Periodically, these sediments should be removed and disposed of. To do so,the pond must be accessible. However, in the proposed design, no access is provided. C. Provide a 50 foot buffer. The proposed 25 foot buffer between the wetland and the lot boundaries is inadequate. Homeowners will landscape yards and construct fences up to their lot lines, which will result in garden chemicals and eroded soil being carried from the yards towards the wetland. An effective buffer is needed to prevent these pollutants from entering the wetland. A wider buffer could be created by a conservation easement across the rear 1111 25 feet of the home lots. Natural Resources Commission 9 7 The City staff, the NRC and the Planning Commission have collaborated to create new development standards for wetlands, which include a 50 foot buffer, especially in 411 significant natural areas.These standards have been recommended to the City Council for adoption. Action has been postponed while the staff develops an economic impact assessment of implementing the standards. While the standards have not been adopted and therefore do not directly apply to this proposal, there was strong support for maintaining effective buffers. D. Verify existence of underground storage tarok and remove if necessary. • It has been reported by neighbors of the site that a:gasoline station was located at the corner of Childs and Canal Roads. The application does not address this past use of the site.The NRC is concerned about the potential for underground storage tank (UST) leaks. Because of the station's close proximity and potential effects on the ground water and surface water the status of this tank should be checked. 4. RETAIN EXISTING WILDLIFE CORRIDOR ALONG CANAL ROAD The NRC recommends designing any improvements or realignment of Canal Road to preserve and maximize the retention of the functions and values of the existing wildlife corridor. The proposed design of Canal Road would essentially eliminate this corridor by reducing it to a 25 foot strip along the steep bank of the Canal. The City's Natural Resources Inventory describes the treed corridor along Canal Road and the Oswego Canal as an important link between Bryant Nature Park and the Tualatin River (Site No. W11, Oswego Canal, Natural Resource Values). The NRC recommends retaining the existing wildlife corridor bychanging the alignment and design of Canal Road as follows: 1. Move the alignment of Canal Road to the west at least 75 feet to create a conservation easement. 2. Limit the width of the pavement along Canal Road to a maximum of 20 feet. This • will easily allow two travel lanes and one parking lane, and is in compliance with Natural Resources Commission 0 the City's development standards. 3. Redesign Canal Road as a rural section street. 4. Terminate the road improvements at the internal street (Riverview Drive). 5. Design the road to retain the existing trees along the road, and plant trees to fill in gaps in the canopy created by tree removal. 6. Restrict parking on Canal Road. 5. MINIMIZE TREE AND HABITAT DAMAGE AND REMOVAL The existing trees are a major esthetic amenity, as well as an important element of the Site's habitat value. The streets and building lots have been sited in the treed upland area and the 100-year flood plain. Extensive grading and filling are planned. The plan lacks details of specific control measures to prevent unnecessary tree removal and damage. As presently designed there may be wholesale tree removal, which is neither necessary or acceptable. The NRC recommends several practical measures to retain trees: 1. Do not accept the sketch maps "Area of Tree Removal" (Exhibit 16) or"Area of Vegetation to be Disturbed by Cut or Fill" (Exhibit 13) as defining the extent of permissible tree removal. Require more detailed information on tree removal. 2. Redesign the streets as rural sections to narrow the width of the pavement. This will reduce both the street area and the adjacent cuts and fills. 3. Minimize cuts and fills. Some of the proposed grading is intended to reduce the slope of lots. However, the Slope Analysis (Exhibit 9) shows that the slopes in the area to be graded and filled do not exceed 9%. This is well within tolerance for standard foundations and driveways. S Natural Resources Commission 11 } 4. Provide for tree protection during grading and later construction, bearing in mind the City's limited ability to police improper tree cutting. Refer to attachment, "Tree and Plant Protection", for specific measures. CONCLUSION The NRC unanimously approved the above recommendations at its meeting of September 2, 1992. We would be glad to provide any additional information which the Board may desire. We also wish to express our appreciation to the Development Review Board for its consideration of the natural resource'issues raised by this development proposal. 110 • Natural Resources Commission 12