Natural Habitat Buffer Zones Mitigation & Monitoring Plan

Transcription

1 Natural Habitat Buffer Zones Mitigation & Monitoring Plan LDS Property Larimer County, Colorado prepared for: Landmark Engineering Ltd W. Eisenhower Blvd., Loveland, Colorado & John Stoddard Church of Jesus Christ of Latter Day Saints 50 East North Temple Street, 10 th Floor, Salt Lake City, Utah prepared by: Western Ecological Resource, Inc. 711 Walnut Street, Boulder, Colorado July 2013

2 Table of Contents Section / Title Page 1.0 Introduction Environmental Setting Southwest Natural Habitat Habitat Types to Create Site Characteristics Wetland Landform & Soils Hydrology Vegetation Tallgrass Prairie Landform & Soils Hydrology Vegetation Shortgrass Prairie Landform, Soils & Nutrients Hydrology Vegetation Northeast Natural Habitat Natural Habitats to Create Site Characteristics Wetland Landform & Soils Hydrology Vegetation Tallgrass Prairie Landform & Soils Hydrology Vegetation Shortgrass Prairie Landform & Soils Hydrology Vegetation Maintenance & Monitoring Plan Success Criteria Maintenance Activities Tree, Shrub & Herbaceous Plantings Vegetation Cover & Composition Weeds Erosion Human or Animal Use Monitoring Activities Trees, Shrubs & Herbaceous Plantings Vegetation Cover & Composition Weeds Erosion Human or Animal Use As-Built Assessment Report Annual Reports... 7

3 Table of Contents (continued) Section / Title Page 6.0 Figures Tables References... 18

4 List of Figures Number / Title Page Figure 1. Project Location Map... 9 Figure 2. Vicinity Map Figure 3. Southwest Natural Habitat Figure 4. Northeast Natural Habitat List of Tables Number / Title Page Table 1. Native Tree & Shrub Plantings Table 2. Wetland Planting, Southwest & Northeast Natural Habitats Table 3. Tallgrass Prairie Seed Mix Table 4. Shortgrass Prairie Seed Mix... 17

5 1.0 Introduction The Church of Jesus Christ of Latter Day Saints (LDS Church) is developing plans to build a temple on 16 acres of a ±35.5 acre parcel of land located southeast of the junction of East Trilby and South Timberline Roads near Fort Collins in Larimer County, Colorado. Specifically, the property is located in Section 17 of Township 6 North and Range 68 West (Figure 1). Single family residences (20-25) would be built on the remaining 19.5 acres of the project site and the homes would be clustered to preserve about 10 acres of open space. This project would require the relocation of an irrigation lateral which would impact 17,775 square feet (ft²) of the lateral and adjacent wetlands. This lateral is not regulated by the U.S. Army Corps of Engineers, but is regulated by the City of Fort Collins. The City requires mitigation of impacts to the lateral and its adjacent wetlands. Mitigation for this impact includes the creation of two Natural Habitat Buffer Zones on the LDS Property. They include the Southwest Natural Habitat, which will have a detention pond with wetlands and a tallgrass prairie surrounded by a shortgrass prairie with shrubs and trees, and the Northeast Habitat, which will have a wetland pond, a detention pond with a tallgrass prairie, and a surrounding shortgrass prairie with shrubs and trees. Each Natural Habitat is discussed below in Sections 3.0 and 4.0. Please note, details on tree and shrub plantings in the Natural Habitats will be provided by the landscape contractor. Table 1 identifies trees and shrubs appropriate for the Natural Habitats as well as the number to plant. 2.0 Environmental Setting The LDS property is located in Larimer County near the City of Fort Collins (Figure 2). The Westchase PUD occurs to the north across East Trilby Road and single family homes occur to the west across South Timberline Road. Areas to the south and east are undeveloped agricultural lands amid a few single family residences. The topography of the site slopes gently to the southeast from a high of 4,923 feet to a low of 4,910. The property has no streams or ponded water. An elevated irrigation lateral extends south and then east across the landscape. The property has an agricultural land use history and is currently used to grow pasture grasses and alfalfa. The hayfields are flood irrigated from the lateral. One single family residence is located on the property east of South Timberline Road. Agricultural and residential land uses have eliminated all of the native vegetation from the project site. 3.0 Southwest Natural Habitat 3.1 Habitat Types to Create This 0.86 acre Natural Habitat will have a 2,616 ft² wetland and a 2,451 ft² tallgrass prairie in the bottom of the detention pond, and a surrounding 0.74 acre native prairie with shrubs and trees. 3.2 Site Characteristics As described in the Soil Survey of the Larimer County Area, Colorado (Moreland, 1980), the Southwest Natural Habitat site is characterized by the Fort Collins loam, a deep, well-drained soil that formed in alluvium. A representative profile of this soil has five inches of light gray loam over a 19 inch thick subsoil consisting of brown and pale brown loam. The top 12 inches of this soil will be stripped, stockpiled and used for the Natural Habitats. The native prairie vegetation of the site has been replaced by an agricultural grassland dominated by smooth brome (Bromus inermis), alfalfa (Medicago sativa), orchardgrass (Dactylis glomerata), and timothy (Phleum pretense). 1

6 3.3 Wetland Landform & Soils The wetland will be created in the northeast half of the detention pond. The entire wetland will be underlain with a Bentomat clay liner. The bottom of the wetland will be at an elevation of 4,907.5 feet and be flat. It will have 12 inches of topsoil and a concrete weir at an elevation of 4,908 feet Hydrology Water for wetland development will be provided by stormwater runoff from the developed LDS property to the north. Approximately 4.13 acres of landscape will drain to the wetland. The 2, 10 and 100 year storm events will generate flows of 5.28, 9.05, and cubic feet per second (cfs), respectively. Following precipitation events, the stormwater flows will saturate the 12 inch depth of topsoil, pond water to a depth of six inches, and then flow over the weir to the tallgrass prairie habitat. The 2 year storm event will generate enough stormwater runoff to fill the pond in about three minutes. Between storm events, the standing water may evaporate but the soils will likely remain moist, depending on the time between storm events Vegetation The bottom of the wetland will be planted with 1,200 of the live plants of Table 2. The planting would include three grasses, five rushes, one sedge, and four forbs, all common to the wetlands in the plains of eastern Colorado. The plants will be set out on 18 inch centers. 3.4 Tallgrass Prairie Landform & Soils The 2,450 ft² tallgrass prairie will be created in the southwestern portion of the detention pond and will be underlain by bentomat and have 12 inches of topsoil. This habitat would have a 4:1 slope from the weir to the outlet structure Hydrology Water for the tallgrass prairie will be provided by stormwater runoff. Stormwater will fill the pond to an elevation of 4,908.2 feet and this water will drain in 40 hours. The soils of the pond will likely remain moist between storm events Vegetation The tallgrass prairie will be seeded with the seed mix of Table 3. This seed mix includes nine grasses, one rush, one sedge, and five forbs, all common to wetlands and tallgrass prairies of eastern Colorado. 3.5 Shortgrass Prairie Landform, Soils & Nutrients The landform of the 0.74 acre shortgrass prairie will slope to the detention pond and rise to an elevation of 4,916 feet to create a small hill northwest of the detention pond. Following grading and establishment of the final topography, 12 inches of topsoil would be spread uniformly over the prairie habitat and cultivated to create conditions appropriate for plant growth. Prior to the application of the topsoil to the prairie habitat, a soil scientist will collect soil samples and submit them for standard agronomic testing to determine any fertilizer recommendations. A granular form of fertilizer would be used and uniformly broadcast over the soils of the prairie habitat. In addition, granular mycorrhizae would be applied at the rate of 20 pounds per acre. 2

7 3.4.2 Hydrology A belowground irrigation system will be used to facilitate seed germination and survival of trees and shrubs in the prairie. The system will have sprinkler heads designed to irrigate the entire seeded prairie, as well as drip irrigation on a separate zone for trees and shrubs. It is likely that the system would be used for two years to initiate plant growth. The system would then be abandoned, and aboveground parts would be removed, however buried pipes would remain in place. Installation of the belowground portion of the irrigation system should occur prior to seeding and the planting of trees and shrubs Vegetation The prairie seed mix of Table 4 would be broadcast at the rate of 27 1/8 pounds per acre of pure live seed and raked into the soil. This seed mix is characterized by seven native grasses and eight native forbs common to the prairie of eastern Colorado. Following seeding, the prairie would be hydromulched and tackified. This work should be completed after the trees and shrubs have been planted to minimize foot traffic on top of the hydromulch layer. The hydromulch will be applied per manufacturers specifications with a 100% wood mat-fiber mulch applied at the rate of 2,000 pounds per acre. Startak 600 by Chemstar is to be applied in accordance with manufacturer s directions at the rate of 100 pounds per ton of mulch. 4.0 Northeast Natural Habitat 4.1 Natural Habitats to Create The 1.3 acre Northeast Natural Habitat will have a 4,599 ft² wetland in a pond, a 14,589 ft² tallgrass prairie in the bottom of the detention pond, and 0.88 acres of a native prairie with shrubs and trees. 4.2 Site Characteristics The existing condition of this site is similar to that described for the Southwest Natural Habitat in Section 2.2, i.e. it has the same soils and agricultural vegetation. Approximately 12 inches of topsoil would be stripped, stockpiled and used for the Natural Habitats. 4.3 Wetland Landform & Soils A 4,599 ft² wetland will be created in the bottom of a pond. The pond will be at an elevation of 4,906 feet and have a bentomat liner with 12 inches of topsoil. A concrete weir at an elevation of 4,906.5 ft² will result in the ponding of six inches of water Hydrology Water for wetland development will be provided by stormwater runoff from the developed LDS property to the west. Approximately 4.97 acres of landscape will drain to the wetland. The 2, 10 and 100 year storm events will generate flows of 4.82, 8.28, and cfs, respectively. Following precipitation events, the stormwater flows will saturate the 12 inch depth of topsoil, pond water to a depth of six inches, and then flow over the weir. The 2 year storm flow would fill the wetland pond in 16 minutes. Between storm events, the standing water will evaporate but the soils will likely remain moist, depending on the time between storm events Vegetation The 4,559 4,599 ft² wetland will be planted with 2,000 live plants of Table 2 on 18 inch centers. This planting is characterized by three grasses, five rushes, one sedge, and four forbs. 3

8 4.4 Tallgrass Prairie Landform & Soils A tallgrass prairie would be created in the bottom of the detention pond, which would have a bentomat clay liner. The detention pond would have a concrete weir at an elevation of 4,904 feet and an overflow structure resulting in the ponding of water to a depth of one foot for 40 hours. The bottom of the pond, the extent of the 4,904 foot contour, would have 12 inches of topsoil Hydrology Water for wetland development will be provided by stormwater runoff from two drainage areas on the LDS property to the west. Approximately acres of landscape will drain to the wetland. The 2, 10 and 100 year storm events will generate flows of 21.21, 35.71, and cfs, respectively. Following precipitation events, the stormwater will saturate the 12 inch depth of topsoil, impound water to an elevation of 4, feet and a depth of 12 inches, and then flow across the weir. The impounded water would entirely drain over a 40 hour period Vegetation The tallgrass prairie will be seeded with the seed mix of Table Shortgrass Prairie Landform & Soils The shortgrass prairie will surround the detention pond and the wetland swale. Following grading and establishment of the final topography, 12 inches of topsoil would be spread uniformly over the prairie habitat and cultivated to create conditions appropriate for plant growth. Prior to the application of the topsoil to the prairie habitat, a soil scientist will collect soil samples and submit them for standard agronomic testing to determine any fertilizer recommendations. A granular form of fertilizer would be used and uniformly broadcast over the soils of the prairie habitat. In addition, granular mycorrhizae would be applied at the rate of 20 pounds per acre Hydrology A belowground irrigation system will be used to facilitate seed germination and survival of trees and shrubs in the prairie. The system will have sprinkler heads designed to irrigate the entire seeded area, as well as drip irrigation on a separate zone for trees and shrubs. The system would be used for two years to initiate plant growth. The system would then be abandoned, and aboveground parts would be removed, however buried pipes would remain in place. Installation of the belowground portion of the irrigation system should occur prior to seeding Vegetation The prairie seed mix of Table 4 would be broadcast and raked into the soil. This seed mix is characterized by seven native grasses and eight native forbs common to the prairie of eastern Colorado. Following seeding, the prairie would be hydromulched and tackified. This work should be completed after the trees and shrubs have been planted to minimize foot traffic on top of the hydromulch layer. The hydromulch will be applied per manufacturers specifications with a 100% wood mat-fiber mulch applied at the rate of 2,000 pounds per acre. Startak 600 by Chemstar is to be applied in accordance with manufacturer s directions at the rate of 100 pounds per ton of mulch. 4

9 5.0 Maintenance & Monitoring Plan 5.1 Success Criteria Success criteria have been developed for the Natural Habitats in order to measure the progress of Natural Habitat establishment and to determine when they are successful and established. The Natural Habitats will be considered successful when: Shortgrass Prairie It is dominated by plants of the shortgrass prairie seed mix or desirable native colonizers. It has a plant species diversity of 10 plants native to the shortgrass prairie of eastern Colorado. It has an absolute vegetation cover of 30% after three seasons of growth. It is self-perpetuating. The absolute cover of noxious weeds is less than 5% and there are no areas of noxious weeds greater than 100 ft². Tallgrass Prairie It is dominated by plants of the tallgrass prairie (detention pond) seed mix or desirable native colonizers. It has a plant species diversity of 10 plants native to the tallgrass prairie of eastern Colorado. It has an absolute vegetation cover of 30% after three seasons of growth. It is self-perpetuating. The absolute cover of noxious weeds is less than 5%. Wetland It is dominated by plants of the herbaceous wetland plantings, wetland and tallgrass prairie seed mixes, and/or desirable native colonizers. It has a plant species diversity of 10 plants native to wetlands and tallgrass prairies of eastern Colorado. It has an absolute vegetation cover of 50% after three seasons of growth. It is self-perpetuating. The absolute cover of noxious weeds is less than 5%. Woody Plantings 90% of the 18 trees and the 200 shrubs are alive one year following termination of the drip irrigation system. Natural Habitat 0.86 acres has been created at the Southwest Natural Habitat acres has been created at the Northeast Natural Habitat. 5.2 Maintenance Activities At regular intervals during the growing season, an ecologist will visit the two Natural Habitats to assess the success of the woody and herbaceous plantings and seed mixes, and note any problems with the hydrology, weeds, erosion, or human or animal use. 5

10 5.2.1 Tree, Shrub & Herbaceous Plantings We will verify that the irrigation system is working and providing adequate water to the shrubs and trees. If adjustments need to be made to the irrigation system or the frequency of watering needs to be modified, we will notify the landscape contractor that changes need to be made. We will also evaluate the health of the shrubs and trees. Specifically, we will determine if the shrubs and trees are alive and producing an annual growth, and if the foliage is healthy. We will also evaluate the success of the herbaceous nursery stock planted in the wetlands to determine the survival rate and the potential need for additional planting Vegetation Cover & Composition We will review the seeded area to determine if the plants of the seed mix are germinating, producing a uniform cover, maturing, and producing seed. We will identify any areas with inadequate seed germination and cover, and reseed where necessary Weeds We will identify any populations of introduced plants including Colorado noxious weeds and other undesirable plants within the seeded areas. We will identify the species present and implement appropriate control procedures. Control procedures may include hand pulling or eradication with hand tools, mowing, or the use of herbicides Erosion Wind and water erosion have the potential to alter the landform of the Natural Habitats. Therefore, we will identify any eroded areas and use hand tools to restore all areas of erosion. Eroded areas will be reseed and/or planted where necessary Human or Animal Use We will determine if human or animal uses impact the Natural Habitats. If impacts are occurring, we will provide recommendations for procedures to eliminate or mitigate the impacts. Procedures to eliminate impacts may include signage to keep pedestrians out of the Natural Habitats, and temporary fencing or animal retardants to eliminate shrub browsing by deer. 5.3 Monitoring Activities We will quantitatively and qualitatively monitor the Natural Habitats each growing season, following seeding and planting, for three years following seeding and planting Trees, Shrubs & Herbaceous Plantings At the end of each growing season, we will determine the number of living and healthy trees and shrubs per species. If the tree and shrub survival rate is less than 90%, additional plantings will be added Vegetation Cover & Composition Vegetation cover in the prairie habitats will be annually quantified using a point-intercept method (Mueller-Dombois & Ellenberg, 1974) along permanent 25 meter long transects in each habitat. Specifically, two transects will be located in each of the three habitat types. At each half meter interval of the transect, one point will be recorded on each side of the transect, perpendicular to and 0.50 meters from the transect. Thus, one hundred points will be sampled at one half meter intervals along each 25 meter long transect. A tripod mounted ocular sighting instrument, with fine cross hairs for point definition and a magnification lens, will be used to collect the vegetation cover data. The sighting instrument has an adjustable mirror to allow sampling of overstory vegetation. At each sample point, the tripod with the attached ocular sighting instrument will be centered, and the adjustable arm will be oriented perpendicular to the transect, first on the right and then on the left. If overstory 6

11 vegetation is present, the sighting device will be directed upward to record any overstory vegetation and then directed downward to record any vegetation in potential shrub and herbaceous canopies. Vegetation along the vertical profiles will be recorded as first or second hits depending on the structural diversity of the Natural Habitats. If vegetation is not present along the vertical profile, soil, rock, or litter will be recorded. All vegetation hits will be recorded by species. For each vegetation cover transect, the percent absolute cover of vegetation, rock, soil, or litter will be calculated using only first hit data. The relative cover of each plant species will be calculated using both first and second hit data. Data on tree and shrub density will be collected by identifying and listing all trees and shrubs present in a four meter wide by 25 meter long quadrat centered along the cover transect. Tree and shrub density will be calculated by counting the total number of trees and shrubs present in each 100m² (4 meter by 25 meter) quadrat. We will also prepare a list of all plants growing in the Natural Habitats, identify their likely source, including commercial seed mix, plantings, soil seed bank, or invader from the surrounding area. We will also indicate if the plants are native or introduced Weeds We will monitor the success of the weed eradication procedures on populations of weeds within the Natural Habitats Erosion We will monitor the success of repairs to any eroded areas Human or Animal Use We will monitor the success of procedures designed to eliminate human and animal impacts to the Natural Habitats. If the recommended procedures are ineffective, alternative procedures will be developed. 5.4 As-Built Assessment Report Following earthwork, planting and seeding, an As-Built Assessment Report will be prepared and submitted to the City of Fort Collins. The Report will document the landforms created, all aspects of the Natural Habitats including the volume of topsoil salvaged and used in the Natural Habitats, fertilizer type used and application rate, seed mix and seeding methods, mulch and tackifiers, erosion control blankets, and tree and shrub planting. 5.5 Annual Reports An Annual Monitoring Report will be prepared to document the monitoring and maintenance activities conducted during the growing season and evaluate the progress of the Natural Habitats in meeting the success criteria. 7

12 8 6.0 Figures

13 105 4'0"W 105 3'0"W 105 2'0"W 105 1'0"W 40 28'0"N 40 28'0"N 40 29'0"N 40 29'0"N 40 30'0"N 40 30'0"N 40 31'0"N 40 31'0"N 105 4'0"W 105 3'0"W BASE: USGS 7.5' Loveland, Colorado Quadrangle " 105 2'0"W 105 1'0"W Figure 1. Project Location Map LDS Church Property Map Location COLORADO Scale±1:40,000 9

14 105 5'0"W 105 4'0"W 105 3'0"W 105 2'0"W 105 1'0"W 105 0'0"W 40 27'0"N 40 27'0"N 40 28'0"N 40 28'0"N 40 29'0"N 40 29'0"N 40 30'0"N 40 30'0"N 40 31'0"N 40 31'0"N 40 32'0"N 40 32'0"N 105 5'0"W Legend 105 4'0"W 105 3'0"W 105 2'0"W 105 1'0"W 105 0'0"W Figure 2. Vicinity Map LDS Church Property LDS Property Boundary Scale±1:60,000 Background: Bing Maps Aerial 10

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17 Tables

18 Table 1. Native Tree & Shrub Plantings TABLE 1 Native Tree & Shrub Plantings Natural Habitats LDS Church Property Scientific Name Common Name Number to Plant Southwest Northeast Trees Populus deltoides Plains cottonwood 3 6 Salix amygdaloides Peachleaf willow 3 6 Total Trees 6 12 Shrubs Prunus Americana American plum Prunus virginiana Chokecherry ssp. melanocarpa Rhus triobata Skunkbrush sumac Ribes aureum Golden currant Rosa woodsii Woods rose Total Shrubs GRAND TOTAL

19 Table 2. Wetland Planting, Southwest & Northeast Natural Habitats TABLE 2 Wetland Planting Southwest and Northeast Natural Habitats LDS Church Property Scientific Name Common Name Wetland Status* Number to Plant Southwest Northeast Grasses, Sedges & Rushes Beckmannia syzigachne Sloughgrass OBL Carex nebrascensis Nebraska sedge OBL Eleocharis palustris Creeping spikerush OBL Glyceria grandis American mannagrass OBL Juncus torreyi Torrey s rush FACW Poa palustris Fowl bluegrass FACW Scirpus acutus Hardstem bulrush OBL Scirpus pungens Threesquare bulrush OBL Scirpus paludosus Alkali bulrush OBL Total Grasses, Sedges & Rushes 1,050 1,750 Forbs Asclepias incorata Swamp milkweed OBL Helianthus nuttallii Marsh sunflower FAC Iris missouriensis Rocky Mountain iris FACW Sparganium eurycarpum Burreed OBL Total Forbs GRAND TOTAL 1,200 2,000 *Wetland Status (2012 Great Plains List) OBL = Obligate Wetland FACW = Facultative Wetland FAC = Facultative FACU = Facultative Upland UPL = Obligate Upland NI = No Indicator (insufficient information) 15

20 Table 3. Tallgrass Prairie Seed Mix TABLE 3 Tallgrass Prairie Seed Mix Natural Habitats LDS Church Property Scientific Name Common Name Seeding Rate PLS lbs./acre Grasses, Sedges & Rushes Andropogon gerardii Big bluestem 2 Carex praegracilis Clustered field sedge ¼ Glyceria striata Fowl mannagrass ¼ Panicum virgatum Switchgrass 3 Pascopyrum smithii Western wheatgrass 4 Poa palustris Fowl bluegrass ¼ Puccinellia airoides Nuttall alkaligrass ¼ Scirpus paludosus Alkali bulrush 1½ Sorgastrum nutans Indian grass 3 Spartina pectinata Prairie cordgrass 4 Sporobolous airoides Alkali sacaton ¼ Total Grasses, Sedges & Rushes 18¾ Forbs Asclepias incarnata Swamp milkweed ½ Helenium autumnale Sneezeweed ¼ Helianthus nuttallii Marsh sunflower 1 Polygonum pensylvanica Giant smartweed 2 Solidago canadensis Canada goldenrod 1/8 Total Forbs 3 7/8 GRAND TOTAL 22 5/8 * Broadcast seeding rate. Halve application rate for drill method. 16

21 Table 4. Shortgrass Prairie Seed Mix TABLE 4 Shortgrass Prairie Seed Mix Natural Habitats LDS Church Property Scientific Name Common Name Seeding Rate PLS lbs./acre * Grasses Aristida purpurea Red threeawn 2 Buchloe dactyloides Buffalograss 8 Chondrosum gracile Blue grama 3 Elymus elymoides Squirreltail 2 Pascopyrum smithii Western wheatgrass 6 Poa secunda Sandberg bluegrass ½ Stipa comata Needle and thread 4 Total Grasses 25½ Forbs Artemisia frigida Fringed sage 1/16 Erysimum asperum Plains wallflower 1/8 Gaillardia aristata Blanket flower ¼ Ipomopsis aggregate Scarlet gilia ¼ Liatris punctata Gayfeather ½ Ratibida columnifera Prairie coneflower ¼ Rudbeckia hirta Gloriosa daisy 1/16 Sphaeralcea coccinea Scarlet globemallow 1/8 Total Forbs 1 5/8 GRAND TOTAL 27 1/8 * Broadcast seeding rate. Halve application rate for drill method. 17

22 8.0 References Moreland, Donald C Soil Survey of the Larimer County Area, Colorado. USDA Soil Conservation Service and Forest Service in cooperation with Colorado Agricultural Experiment Station. December Mueller-Dombois & Ellenberg Aims and Methods of Vegetation Ecology. John Wiley & Sons, Inc. New York. 18