HomeMy WebLinkAboutRIDGEWOOD HILLS FIFTH FILING - PDP190018 - SUBMITTAL DOCUMENTS - ROUND 3 - WETLANDS DOCUMENTS1
Preliminary 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
April 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 1:1 basis. Thus
wetland mitigation/creation of new wetlands is proposed for at least 0.49 acres.
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2.0 Mitigation Requirements and Assumptions
Wetland mitigation requirements include:
At least 0.49 acres of new wetland area will be created on the site to mitigate for the 0.49
acres of wetland loss. Note: additional wetlands (beyond the 0.49 acres) may be created
in detention areas, 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. 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.
c. 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 actions.
3.0 Monitoring Procedures
Preconstruction Monitoring
Preconstruction monitoring will be completed to characterize existing wetland vegetation (at the
end of the growing season) and existing wetland hydrology (through the growing season) in and
around Wetland 4 (including proposed wetland mitigation areas around Wetland 4).
At least 6 wetland monitoring points will be established in and adjacent to Wetland 4.
Preliminary locations of monitoring points are shown on Figure 1. Note: monitoring point
location may vary according to final project design (location of mitigation areas) and field
conditions. 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 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
related to the seasonal flows of the North Louden Ditch. At this time it is assumed that wetland
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hydrology in and adjacent to Wetland 4 is related to seasonal flows in the earthen North Louden
Ditch.
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) 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. Preliminary 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
adjacent to Wetland 4. The monitoring points shown in Figure 1 will be used for post
construction monitoring unless they need to be changed to reflect actual wetland mitigation sites.
The 6 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 at each monitoring point 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.
The annual monitoring efforts will be summarized in a Wetland Monitoring Report.
The results of post construction Wetland Monitoring will help determine if wetland mitigation is
successful, if other remedial actions need to be taken to ensure mitigation success (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.
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.
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.
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