HomeMy WebLinkAboutRIDGEWOOD HILLS - FDP230019 - SUBMITTAL DOCUMENTS - ROUND 3 - Supporting Documentation (9)Wetland Monitoring Plan- Ridgewood Hills Project
Prepared For:
Goodwin Knight
8605 Explorer Drive, Suite 250
Colorado Springs, CO 80920
Prepared By:
Wildland Consultants, Inc.
1001 Jefferson Drive
Berthoud, CO 80513
August 2020
1.0 Project Overview
The Ridgewood Hills development is located in south Fort Collins, Colorado. The site is bounded
on the north by Triangle Drive and South College Avenue on the east. The proposed residential
development is located on a total of approximately 34+- acres. The development includes single
family residential, multi-family residential and commercial uses. The existing site includes
wetlands, the North Louden Ditch, and seeded grasslands. After construction approximately
10.85 acres +- will be designated as open space. Proposed open space areas include existing
wetlands, wetland mitigation areas, portions of the North Louden Ditch, and other open areas.
Open space areas are designed to mitigate for lost wetlands, ditch and Natural Habitat Buffer
zones.
Wildland Consultants, Inc. (WCI) completed a formal wetland delineation and Wetland
Delineation Report for the project in 2019 (WCI 2019). The Wetland Delineation Report was
sent to the Army Corps of Engineers (ACOE) for review. WCI requested an approved
Jurisdictional Determination for wetlands on the site from the ACOE. The ACOE determined that
all of the wetlands on the site are non-jurisdictional (ACOE 2019). Wetland mitigation is being
proposed on the site to meet City of Fort Collins requirements not ACOE requirements.
Currently project construction is proposed to remove 0.49 acres of wetlands on the site. These
wetlands are mainly associated with the North Louden Ditch. The City of Fort Collins will
require mitigation for these lost wetlands. Mitigation will be completed on a 1:2 basis. Thus
wetland mitigation/creation of new wetlands is proposed for at least 1 acre (not including wetland
created in detention ponds).
2.0 Mitigation Requirements and Assumptions
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Wetland mitigation requirements include:
At least 1 acre of new wetland area will be created on the site (adjacent to Wetland 4) to
mitigate for the 0.49 acres of wetland loss. In addition 0.71 acres adjacent to Wetland 4
will be enhanced with plantings of riparian vegetation (shrubs and trees) to create
structural diversity and to enhance wetland functions for wildlife. Note: additional
wetlands (beyond the 1 acre) will be created in detention areas. Weed control (Canada
thistle) will be completed on and adjacent to Wetland 4. Wetland functions of mitigated
wetlands will be equal to wetland functions of lost wetlands.
Wetland Mitigation will determined to be successful when:
a. At least 80% (determined by ocular estimate of herbaceous and shrub foliar cover) of
the mitigation site(s) is vegetated, at least 50% of the total number of dominant species
present will consist of species rated as facultative or wetter.
b. Riparian shrub and tree survival will be at least 80%.
c. Those species shown on the Colorado Noxious Weed Inventory list-A shall be 100%
eradicated. Those species shown on list-B shall be no more than 10% or less of the total
cover in the mitigation area. Weed control will follow the Weed Management Plan
prepared for the project.
d. Wetland hydrology and wetland soils are present (as defined by ACOE delineation
standards).
Annual Mitigation Monitoring Reports will be submitted to the City of Fort Collins.
Note: wetland mitigation takes time. It is likely that mitigation requirements will take 3-5
years to be met.
The success of wetland mitigation is never a guarantee. Changes in climate, changes in
ditch flow, changes in hydrology due to offsite factors can all impact the success of
wetland mitigation. If post construction wetland monitoring indicates problems with
wetland mitigation, the project proponent will consult with the City of Fort Collins to
determine appropriate remedial/adaptive management actions.
3.0 Monitoring Procedures
Preconstruction Monitoring
Preconstruction monitoring will be completed to characterize existing wetland vegetation (at the
end of the growing season), soils (wetland characteristics) and existing wetland hydrology
(through the growing season) in and around Wetland 4 (including proposed wetland mitigation
areas around Wetland 4).
WCI installed 9 shallow ground water wetland monitoring wells (MW) in and adjacent to Wetland
4 (MW 1-9) in late May/early June 2020. Two existing monitoring wells (MW10-11) were also
located and will be included in the monitoring program. Locations of monitoring points are
shown on Figure 1. A staff gauge (SG1) was placed in the North Louden Ditch to the west of
Wetland 4. The goal of the groundwater monitoring will be to determine the depth of ground
water within and adjacent to Wetland 4. By placing the staff gauge ground water depth can be
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related to the seasonal flows of the North Louden Ditch. At this time it is assumed that wetland
hydrology in and adjacent to Wetland 4 is related to seasonal flows in the earthen North Louden
Ditch. In addition, precipitation (from the nearest weather station) will be determined for each
monitoring period.
Attachment A provides details regarding the establishment of MW’s, including installation, and
monitoring techniques. Each MW will be monitored twice monthly during the growing season
(May- September) and once monthly outside the growing season (October-April) for at least 1-2
years prior to project construction (depending on construction schedule).
Vegetation and soil monitoring at each monitoring point will be completed at the end of the
growing season (September-early October). Photos will be taken at each monitoring point.
Ocular estimates will be used to determine plant cover (1 meter circular plot). Soil will be
evaluated by digging a soil pit and characterizing soils according to ACOE standards.
Annual monitoring efforts will be summarized in a Wetland Monitoring Report.
The results of preconstruction monitoring will help guide wetland mitigation efforts (mitigation
areas adjacent to Wetland 4) and wetland protection/enhancement efforts for Wetland 4.
Knowledge of ground water levels (and levels to saturated soils) will inform proposed wetland
mitigation. For example, ground water levels at 16-inches in a proposed mitigation area would
indicate that the area should be excavated to a depth 12-16 inches to ensure saturated soils at the
Figure 1. Monitoring Point/MW Locations in and adjacent to Wetland 4.
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surface of the proposed mitigation area. Groundwater monitoring data will provided to the project
engineer for use in planning wetland mitigation.
3.2 Post Construction Monitoring
Post construction monitoring will focus on Wetland 4 and on constructed mitigation areas and
enhancement/restoration areas adjacent to Wetland 4. The MW’s shown in Figure 1 (note: actual
MW locations may be different) will be used for post construction monitoring unless they need to
be changed to reflect actual wetland mitigation sites.
The wetland monitoring points in and adjacent to Wetland 4 will be monitored for a period of 3-5
years (until wetland mitigation is determined to be successful). A ground water monitoring well
(MW) will be located at each monitoring point. In addition to the MW’s a staff gauge will be
placed in the North Louden Ditch to the west of Wetland 4. The goal of the post construction
groundwater monitoring will be to determine the depth of post construction ground water within
Wetland 4 and within mitigation areas adjacent to Wetland 4. By placing the staff gauge post
construction ground water depth can be related to the seasonal flows of the North Louden Ditch.
Vegetation and soil monitoring will be completed along 5-8 point intercept transects. Photos will
be taken along each transect at the end of the growing season (September-early October).
Ocular estimates will be used to determine plant cover. Soil will be evaluated by digging a soil
pits and characterizing soils according to ACOE standards.
The annual monitoring efforts will be summarized in a Wetland Monitoring Report.
Adaptive management will be completed as needed to address problems with wetland mitigation.
The entities responsible for adaptive management will include the City of Fort Collins and the
Developer/Owner. If erosion issues, weeds, lack of wetland hydrology or other issues occur over
the monitoring period the City of Fort Collins and the Developer/Owner will work together to
determine what actions are needed to meet wetland mitigation performance criteria (see Section
2.0).
The results of annual post construction Wetland Monitoring will help determine if wetland
mitigation is successful, if other remedial/adaptive management actions need to be taken to ensure
mitigation success (for example weed control, supplement water or other measures).
4.0 References
Army Corps of Engineers, 2019. Approved Jurisdictional Determination, Triangle Project.
Wildland Consultants, Inc. 2019. Wetland Delineation Report Triangle Project.
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Attachment A-GROUNDWATER MONITOR WELL INSTALLATION AND
MONITORING SPECIFICATIONS
GROUNDWATER MONITOR WELL INSTALLATION AND
MONITORING
Installation material
PVC solid pipe – 1” through 2”diameter works well. Must be of an inside diameter that
will allow access for well reader. Some well readers may not fit inside 1” PVC, especially
if its Schedule 80 (mil slot is typically constructed from schedule 80).
20 mil slot PVC. For each well a 3 foot long slotted PVC section at the bottom is
sufficient.
2 PVC caps for each well to be installed (extras sometimes needed)
1 PVC coupling for each well to be installed (extras sometimes needed)
Hacksaw for cutting PVC
Permanent marker for numbering wells
Auger of appropriate diameter and length to drill well
Measuring tape
Well log forms
Well Installation Methods
The installation methods described below are for wells where data will reflect a composite water pressure
over the perforated section of pipe. This is in contrast to a Piezometer, where water is allowed to only
enter the pipe through a short length of screen at the bottom of the pipe.
1.Locate the site where the well is to be installed by mapping or on-site determination.
2.Begin drilling the well and record characteristic of the borehole material on the data sheet.
Important attributes to record are depth when groundwater is encountered, depth to gley and
thickness of gley layer, texture of bore material, changes in texture of soils that may indicate a
confining layer (such as clays), depth and thickness of iron staining, and other information
characterizing the borehole.
3.Drill well to appropriate depth. This depth depends on anticipated groundwater elevation changes
over the monitoring period. Wells three (3) feet deeper than the depth where groundwater is first
encounter are usually adequate.
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4.Assemble the well pipe string using a cap at the bottom, a 3 foot section of 20 mil slot PVC,
coupling, solid PVC pipe, and cap at the top. Be sure all section are butted. Leave sufficient length
of solid PVC so that the pipe can be cut off at a height of 1 foot above the natural ground surface
(stick-up). USE NO GLUE DURING INSTALLATION.
5.Insert the assembled pipe into the bored hole insuring that the pipe is all the way to bottom. Cut off
the solid PVC at the surface to an elevation of 1 foot above natural ground surface. Be sure cut is
perpendicular to pipe. Make a vertical cut down one side of the pipe approximately 2 inches below
the top of the casing (this makes removal of the cap easier and prevents vacuums inside the casing).
6.Back fill the borehole with material used from the boring. Mound excess material up around the
pipe at the surface to prevent ponding of water around the well pipe.
7.Label well casing on the INSIDE UPPER SURFACE of the well cap using a permanent marker.
Wells are labeled W1, W2 …. W10.
8.Complete the borehole data sheet including, UTM or Lat/Long location, well number, depth when
water was encountered during drilling, other well bore characteristics, total length of pipe used
(slotted and solid), size of slots in slotted pipe, total depth of well, stick-up of pipe above the
ground surface, and plant community at well location.
9.Depending on textures encountered during drilling, well water depth can be monitored 1 hour
(sandy, gravelly strata) to 8 hours (silts and clays) after completion of well. All well readings are
taken from the top of the PVC casing.
10.Monitor wells will need to be shot-in in to determine relative elevation to other well locations and
surface water features. Elevation of the Top of Casing (TOC) and nearby natural ground surface
will provide information necessary to interpreting well data.
STAFF GAUGE INSTALLATION
Installation Material
Five (5) foot long Tee-post
Post pounder
Measuring tape
Data sheet
Permanent marker and/or metal tag
Staff Gauge Installation Methods
Staff gauges are used to measure surface water locations.
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1.Locate the site where the staff gauge is to be installed by mapping or on-site determination. Deep-
water locations are best as they will cover a wider range of water fluctuations.
2.Drive Tee-post into ground approximately 2 feet.
3.Label Tee-post SG1, SG2……SG10.
4.Complete the Staff Gauge data sheet including stick-up and distance from top of Tee-post to water
surface.
5.Staff gauges will need to be shot-in in to determine elevation and location. Elevation of the Top of
Tee-post and ground surface at Tee-post base will provide information necessary to understand
Staff Gauge data.
WELL AND STAFF GAUGE MONITORING AND OTHER DATA COLLECTION
Wells and staff gauges will be monitored periodically (weekly to monthly) depending on
hydrologic inputs, such as ditch/ canal flows, over the growing season from the period of May 1
through September 30.
Events such as flooding, rainstorms, surface irrigation in the area, or other events that can effect
ground and surface waters will be noted by date of occurrence.
Other data such as precipitation or USGS staff gauge information from other nearby stations
should be obtained at the end of the monitoring season and used for analysis.
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MONITOR WELL/STAFF GAUGE INSTALLATION DATA SHEET W/SG No._________
UTM or Lat/Long_____________________________________________
Date_________Recorded By ________
Total Well Depth ___________
Stick-up ___________
Screen Length ___________
Screen Slot Size ___________
Depth to Water ___________
Water Odor ___________
Water Color ___________
Plant Community ___________
Soil Name ___________
Staff Gauge Stick-up
From Ground Surface ___________
Distance from Top of
Tee-post to water
Surface ___________
NOTES:
Soil Color Soil Texture
Hardness Organic lenses
Structure Gley Layer
Cementation Mottles
Iron Staining Clay Lenses
Concretions
Soil Profile Log
From – To (feet)Description