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HomeMy WebLinkAboutRIVER DISTRICT BLOCK ONE MIXED-USE (ENCOMPASS) - PDP - PDP120020 - REPORTS - ENVIRONMENTAL REPORT (5)August 24, 2012 Rich Shannon Pinnacle Consulting Group, Inc. 5110 Granite Street, Suite C Loveland, CO 80538 RE: Revised Ecological Characterization Study (ECS) Letter Report for the River District Block One Mixed Use – Encompass Development Site Rich: This letter report has been revised to address City of Fort Collins comments received on the previous PDP Submittal for the River District Block One Mixed Use – Encompass (Block One) development proposal The Block One site is situated between on the south side of Linden Street and adjacent to the west side of the Cache la Poudre (Poudre) River. Ecological characteristics of the property were reviewed during an on-site meeting with City of Fort Collins staff, you, and me on March 6, 2012. The following provides a summary of information required by Fort Collins Land Use Code under 3.4.1 (D) (1) items (a) through (k). ECOLOGICAL STUDY CHARACTERIZATION CHECKLIST (a & i) The proposed Block One site has minimal ecological value and supports no natural habitat features. The majority of the property’s surface is paved with either concrete or asphalt. The few level unpaved surfaces and the embankment on the west side of the property have been cleared of native vegetation by past industrial activities and only support annual weeds such as cheatgrass (Bromus tectorum), field bindweed (Convolvulus arvensis), kochia (Bassia scoparia), common dandelion (Taraxacum officinale), and Russian thistle (Salsola tragus), as well as few Siberian elm (Ulmus pumila) seedlings. The property does not support any native vegetation, wetlands, or other unique habitat features. Features of ecological value within 500 feet of the development site consist primarily of the Cache la Poudre River and the riparian corridor supported along both sides of the river. The riparian corridor between the property boundary and the Poudre River is very narrow and most trees are growing on a very steep embankment. The embankment has been stabilized in the past with blocks of broken concrete. Trees supported on the embankment consist of seven Siberian elms, eight multi- trunked peachleaf willows (Salix amygdaloides), two eastern cottonwoods (Populus deltoides), and one small, multi-trunked ponderosa pine (Pinus ponderosa). Wildlife use of the Block One site is minimal to nonexistent because of past disturbance and lack of vegetation cover. Wildlife use of the adjacent riparian corridor is restricted primarily to urban adapted songbirds because of surrounding human development and activities and a lack of any kind of a shrub or herbaceous understory because of past bank stabilization practices. No raptor or songbird nests were located in trees adjacent to the Block One site during the March site survey, but it is possible some songbird nesting may occur in these trees. Raptor nesting use of these trees is unlikely due to surrounding human activities and the very narrow configuration of this section of the riparian corridor. Waterfowl and other water birds use the adjacent portions of the river corridor for movement, loafing, and feeding activities. (b) No wetlands are located on the Block One site and wetlands are minimal to nonexistent along the adjacent riverbank because of the steepness of the bank and past bank stabilization by concrete block placement. (c) Currently the Block One site does not provide any significant or unobstructed views of natural areas or other important visual features. Existing trees along the riverbank obscure views of the river corridor. (d) As indicated under (a & i) the Block One site does not support any native vegetation and significant trees are restricted to the riverbank adjacent to the east property boundary. (e) There are no natural drainages on the Block One site. However, the Poudre River corridor is immediately adjacent to the east property boundary. R. Shannon 8/24/12 Page 2 of 4 (f) Because of past industrial disturbance of the Block One site and bank stabilization practices on the adjacent riverbank, there is no suitable habitat for any threatened, endangered, or other sensitive species on or adjacent to the Block One property. (g) Past industrial disturbance of the Block One property has also eliminated the potential for any special habitat features on the site. (h) Past industrial disturbance of the Block One property, surrounding development, and the very steep river embankment has minimized the potential for wildlife movement corridors along the west side of the Poudre River. Waterfowl and other waterbirds use adjacent portions of the Poudre River for movement, loafing, and feeding activities. (j) Because of the general lack of natural habitat features on the Block One site and the highly modified nature of the adjacent river embankment, there is only one issue regarding the timing of property development and ecological features or wildlife use of the project area. The current proposal is to remove three Siberian elm trees and prune other trees to be preserved along the top of the river embankment. No raptor nests were found in trees adjacent to the project site, but these trees could be use for nesting by urban adapted songbirds. Tree removal and pruning during the songbird nesting season could result in the loss or abandonment of a nest and would be in violation of the federal Migratory Bird Treaty Act. Therefore it is recommended that tree removal and pruning occur outside of the songbird nesting season (April 1 – July 31) to preclude the possible incidental take or disturbance of active songbird nests. (k) Development of the Block One parcel would result in relatively minor additional impacts to the Poudre River corridor beyond those that have already occurred from existing disturbance and development. This conclusion is based on the fact that the site has been previously developed and is surrounded by existing development and roadways, except for the east property boundary, which abuts the steep bank and very narrow riparian river corridor. The proposed development would create a minor increase in building density and human presence near the Cache la Poudre River corridor. However, these increases would be fairly minor in relation to existing development and human activities and use patterns associated with surrounding development, vehicular traffic on Linden Street, and human presence and use of the nearby recreation trail. The Block One project site is zoned RDR (River Downtown Redevelopment District) and City buffer zone standards (LUC 3.4.1) do not apply to RDR zones. Based on its current zone designation, lack of any natural habitat features, its location between existing development and roadways, and presence of pavement up to the top edge of the river embankment, the site could be enhanced substantially by planting additional, appropriate native plant species between the top of the embankment and proposed development features. These plantings would create additional buffer between the proposed development and the river corridor. These plantings would also create additional habitat diversity (primarily for songbirds) and visual screening between the development parcel and the river. Native upland shrub and tree plantings would also establish a more natural vegetation transition zone between the river corridor and the proposed development. The site could be further enhanced by planting appropriate native and ornamental species along the new embankment that would be created along the western property boundary. An appropriate landscape and weed management plan needs to be developed to ensure the success of these plantings. A review of Natural Resources Conservation Service (NRCS, formerly SCS) soils mapping for the development site area indicates the Paoli fine sandy loam soil-mapping unit underlies the entire project site up to the river embankment. This is an upland soil that, in an undisturbed state, supports native short-grass prairie species such as blue grama (Bouteloua gracilis), little bluestem (Schizachyrium scoparium), and green needlegrass (Nasella viridula). As indicated by the riparian corridor on the project area side of the river corridor, this soil type can also support native cottonwood, willow trees and other riparian species when more mesic soil moisture levels are created by proximity to the river corridor. Based on these considerations the following mitigation recommendations are provided for the Block One development parcel. The area between proposed development areas and the top of the river embankment should be planted with an upland riparian vegetation mix, including shrubs and trees, to create a transitional zone of native R. Shannon 8/24/12 Page 3 of 4 upland riparian vegetation. The goal of these plantings should be to create a self-sustaining, native vegetation community to stabilize soils and enhance wildlife habitat. Plantings of native shrubs and trees would also provide visual screening between development and important habitat areas. Habitat enhancement plantings would likely require soil treatment to relieve compaction (ripping) and improve fertility (fertilizer amendments). Supplemental irrigation would also be needed for initial establishment of native shrubs and trees. Suggested species for planting include the following deciduous trees and shrubs. Deciduous Trees Deciduous Shrubs eastern cottonwood (Populus deltoides) American plum (Prunus americana) lanceleaf cottonwood (Populus acuminata) big sagebrush (Artemisia tridentata) (both non-cotton bearing varieties) chokecherry (Prunus virginiana) netleaf hackberry (Celtis reticulata) golden currant (Ribes aureum) rubber rabbitbrush (Chrysothamnus nauseosus) serviceberry (Amelanchier alnifolia) skunkbrush sumac (Rhus trilobata) These species could also be used for native plantings on the slope to be created along the western property boundary Maintain, to the extent possible, native trees on the river embankment that were determined to be significant by the City Forester (Tim Buchanon) these trees would also help to maintain slope stability. Removal of any trees classified as significant would need to be mitigated with replacement trees as per Section 3.2.1 (F) of the Land Use Code. This criteria was determined by the City Forester to only apply to one ponderosa pine tree to be removed because of its generally poor condition. Mitigation is not required for the three Siberian elms slated for removal. The primary wildlife habitat value of the three Siberian elms and the one ponderosa pine is for potential nesting by songbirds. As long as the timing mitigation recommendation (see item j) is followed there would be no direct impact to songbirds with the removal of these trees. Loss of future nesting habitat provided by these trees would eventually be mitigated as proposed deciduous shade tree and ornamental tree plantings mature in the landscaped buffer zone between the river and proposed development (see PDP Landscape Plan). The intensity of night lighting from the sides of buildings facing the Poudre River corridor should be shielded or directed to preclude the intrusion of artificial nighttime light into the landscaped buffer zone and adjacent riparian and river corridor. One issue of concern for the property is the stability of the river embankment slope along the eastern property edge. Part of the development proposal is to remove three of the non-native Siberian elm trees along the river corridor to create a more native riparian corridor as well as to create some unobstructed views of the river from the proposed development site. A concern with tree removal is that this may create stability issues with the existing steep embankment. In order to address this issue, the project team retained Flywater, Inc. to evaluate the stability of the existing embankment as well as to determine if removing Siberian elms would create any instability issues. The Flywater report is included as an attachment to this report. In general the report concluded that Siberian elm removal would not create additional instability as long as additional rock armoring is placed in areas of existing undercutting along the toe of the river embankment. Additional geotechnical evaluation of slope stability issues is provided in other PDP submittal documents. Rich, this concludes my evaluation of the Block One development site. If you have any questions or require additional input regarding my evaluation, please give me a call. R. Shannon 8/24/12 Page 4 of 4 Sincerely, CEDAR CREEK ASSOCIATES, INC. T. Michael Phelan, Principal attachment: Flywater, Inc. report