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HomeMy WebLinkAboutPARAGON POINT PHASE FIVE FINAL - 48 91L - SUBMITTAL DOCUMENTS - ROUND 1 - WETLANDS DOCUMENTSRiverside Technology, inc. MEMORANDUM TO: Jim Sell FROM: Stephen Johnson ��6 k•` ti� DATE: May 22, 1995 SUBJECT: Paragon Point V P.U.D. WETLANDS MITIGATION PLAN Background The Paragon Point V P.U.D. involves construction activities that would result in the filling of 0.1 acre of jurisdictional wetlands. This memorandum is written to provide a wetlands mitigation plan to mitigate the losses in wetlands acreage. The wetlands were delineated by Riverside Technology, inc. (RTi) as documented in an RTi report entitled Jurisdictional Wetlands Delineation Survey for the Paragon Point V Site, Fort Collins, Colorado (November 1994) which was approved by the U.S. Army Corps of Engineers (COE) Tri-Lakes Field Office in a December 15, 1995 letter from Terry McKee to Johnson. The site is automatically covered under a Nationwide 26 COE permit because the COE has sufficient information available to determine that the proposed development would result in the loss of less than 1 acre of waters of the U.S., including jurisdictional wetlands acreage. Because the. losses in wetlands acreage is below 1.0 acre, no wetlands mitigation plan is required by the COE. The delineated wetlands contain a wet meadow (palustrine) dominated by herbaceous vegetation that consists of inland saltgrass (Distichlis spicata), fox -tail barley (Hordeum jubatum), and saltmarsh sandspurry (Spergularia marina) and is surrounded by uplands dominated by Kochia a.k.a. Mexican summer -cypress (Kochia scoparia) and wheatgrasses. Hydric soils criteria exist both in and outside of jurisdictional wetland areas, but hydrophytic vegetation and wetland hydrology criteria were not met outside of the jurisdictional wetland areas (upland areas). These conditions are evidence of a wetland area that is in transition towards upland area because of the loss of supporting hydrology. The mitigation of losses in wetlands acreage can be accomplished through either creation of new wetlands or enhancement of existing wetlands. Considering the small acreage of wetland losses (0.1 acre), the mitigation plan is to enhance wetlands that exist in the area. Wetlands enhancement would involve both an increase in functions and values associated with existing wetlands. The wetlands targeted for enhancement are the riparian wetlands along Rock Creek downstream of Lemay Avenue and upstream of the most downstream constructed pond in the Paragon Point development. The riparian wetlands currently do not have any established wetland vegetation stratum other than herbaceous and are found in an area that is naturally erosive. The plan for mitigation of wetland losses is to enhance the existing riparian wetlands along Rock Creek through establishing two more wetland vegetation stratum by planting hydrophytic shrubs and saplings (trees) within the riparian wetlands. As recommended by the COE Tri-Lakes Field Office, the selection 3 of hydrophytic shrub and sapling (tree) species and spacing of plantings would involve coordination with the U.S. Fish and Wildlife Service (USFWS) in Fort Collins. USFWS personnel would recommend more native wetland species and species that provide both greater stability of the naturally erosive soils and greater habitat for terrestrial animals and water fowl that spend part or all of their time in wetlands. The establishment of shrub and sapling (tree) wetland vegetation strata would provide for enhancement of both wetland functions (e.g., habitat and increased soil stability) and wetland values (e.g., bird watching and aesthetics associated with tree establishment). The COE requires a 1:1 mitigation of lost wetlands acreage. For this mitigation plan a 1:3 mitigation is proposed, which would involve the enhancement of 3 x 0.1 acre, or 0.3 acre of existing wetlands. Please call me at 223-2944 with any questions regarding this memorandum. cc: Richard Spotts V1LE- Wetland Mitigation Plan for the Paragon Point V Site Fort Collins, Colorado Prepared for Jim Sell Design, Inc. 117 East Mountain Avenue Fort Collins, Colorado Prepared by Riverside Technology, inc. 2821 Remington Street Fort Collins, Colorado July 1995 BACKGROUND The Paragon Point V P.U.D. involves construction activities that are proposed to fill 0.1 acre of jurisdictional wetlands. This wetland mitigation plan is written to mitigate losses in wetland acreage. The wetlands in the area have been delineated by Riverside Technology, inc. (RTi) as documented in an RTi report entitled Jurisdictional Wetlands Delineation Survey for the Paragon Point V Site, Fort Collins, Colorado (November 1994), which was approved by the U.S. Army Corps of Engineers (COE) Tri-Lakes field office in a December 15, 1995 letter from Terry McKee to Steve Johnson. The site is automatically covered under a Nationwide 26 COE permit because the COE has sufficient information available to determine that the proposed development would result in the loss of less than 1 acre of waters of the U.S., including jurisdictional wetland acreage. Because the losses in wetland acreage are less than 1.0 acre, no wetland mitigation plan is required by the COE. However, the City of Fort Collins has a policy dictating mitigation of wetland losses, even if those losses are less than 1.0 acre. The delineated wetland on the Paragon Point V P.U.D. contain a wet meadow (palustrine) dominated by herbaceous vegetation that consists of inland saltgrass (Distichlis spicata), fox -tail barley (Hordeum jubatum), and saltmarsh sandspurry (Spergularia marina), and surrounded by uplands dominated by Kochia a.k.a. Mexican summer -cypress (Kochia scopara) and wheatgrasses. Hydric soils criteria exist both inside and outside of the jurisdictional wetland area, but hydrophytic vegetation and wetland hydrology criteria were not met outside of the jurisdictional wetland area (upland area). These conditions are evidence of a wetland area that is in transition toward upland area because of the loss of supporting hydrology. Losses in wetland acreage can be mitigated either by creating new wetlands, restoring degraded wetlands, or enhancing existing wetlands. Considering the small acreage of wetland losses (0.1 acre), this mitigation plan proposes enhancing a wetland that exists in the area. Wetland enhancement would involve both an increase in functions and values associated with existing wetlands. A336 0795 MMPfAN.DOC 1 WETLANDS ENHANCEMENT The mitigation area targeted for enhancement is the riparian wetland along Rock Creek downstream of Lemay Avenue and upstream of the most downstream constructed pond in the Paragon Point V development (Figure 1). The mitigation area currently has an established wetland stratum of herbaceous vegetation without any overstory, and is found in an area that is naturally saline, clayey, and erosive. The plan for mitigating wetland losses is to enhance the existing riparian wetland in the mitigation area through establishing two more wetland vegetation stratum by planting hydrophytic shrubs and saplings (trees) within the riparian wetland. Enhanced wetland functions would be obtained by increasing habitat for waterfowl and other birds as nesting sites and cover. Enhanced wetland values would be obtained by establishing a park -like setting in this area. The wetland enhancement goal is to establish three stratum of wetland vegetation in the mitigation area that currently contains only an herbaceous vegetation stratum. As recommended by the COE Tri-Lakes field office, the selection of plantings is best coordinated with the Habitat section of the U.S. Fish and Wildlife Service in Fort Collins. RTi contacted Bob Bogert, Habitat Biologist, to solicit his advise, and the following tree and shrub stratum have been selected for plantings in the mitigation area. Tree Stratum Plains Cottonwood Trees - Plains Cottonwood trees (Populus sargentii) are native, salt tolerant trees that will provide habitat for nesting birds, such as Blue Jays and Robins. Selected trees for planting will be approximately 8 to 10 feet tall with 1- to 1.5-inch diameter trunks. Planting larger trees is discouraged because of the higher probability of stunted growth and unsuccessful transplanting associated with more mature trees. The trees will be spaced every 75 to 100 feet, which will allow for sufficient sunlight to penetrate between trees. Approximately 5 to 6 trees will be planted within 0.3 acre. Specific plantings within the mitigation area are indicated in Figure 1. Shrub Stratum Golden Current and Skunkbrush Shrubs - Golden Current (gibes aureum) and-Skunkbrush(Rhus— _ tribobata) are thick growing, durable shrubs that will provide good cover for wildlife, especially nesting waterfowl. Golden Current is abundant in gulches along the foothill -plains margins. Skunkbrush is also found on open slopes of the foothills, particularly in clay soil, which is a typical soil type of the Rock Creek area. The shrubs will be planted in 2 to.3 clusters in the vicinity of each Cottonwood tree. Each cluster will contain 3 to 5 shrubs. Approximately 30 shrubs of each type will be planted within 0.3 acre. Specific plantings within the mitigation area are indicated in Figure 1. Stormwater Discharge Because the proposed Paragon Point V development plans would result in channelized stormwater flow released at two points into the wetland, impacts that may result would need to be minimized and any wetland losses mitigated. As a preventive measure, stormwater discharges would be designed to minimize the energy of the stormwater flows and to dissipate the channelized flow toward more sheet flow. Erosion of the wetland near the two proposed stormwater discharge points to the wetland A336 OZ95 MrHPIAN.DOC 2 area would be minimized by planting salt -tolerant, sod -forming grasses. Low areas in the wetland topography (where runoff will be concentrated and erosion could occur) will be determined so the planting can be focused on these areas. The grasses that could be planted are Inland Saltgrass (Distichlis spicata) and Fox -Tail Barley (Hordeum jubatum), though other vegetation species may be selected for planting. The proposed sod -forming plant species currently exist in the wetland area. A336 0795 MMPfAN.DOC 3 MITIGATION COMMITMENTS The following mitigation commitments are proposed as part of this mitigation plan: 1. Upon completion of construction at the Paragon Point V development, a wetlands specialist will make a final determination of the amount of disturbance that has occurred to the wetland. If the amount of disturbance exceeds 0.1 acre, the wetland area exceeding this amount would be mitigated in the mitigation area using a 3 to 1 ratio. 2. The growth of tree and shrub plantings in the mitigation area will be monitored for 3 years. Any plantings lost in the mitigation area during this time will be replaced and monitored for an additional 3 years. The monitoring plan is to be conducted by a wetlands specialist. 3. The wetland will be monitored by a wetlands specialist 1 year after completion of the stormwater system to determine if any wetland area has been lost. If loss of wetland area occurs because of stormwater discharge, the lost wetland acreage will be mitigated in the mitigation area using a 3 to 1 ratio. 2 m ro s wow _ . .. Pond 1 ``. _ �r �9 SW"Wakr OUM 0 t00 200 Legend Figure 1. O Cottonwood Tree and Tree Planting Locations shrub plantings N Mitigation Area J (0.3 acre) r