Stratford Mnr/FP-CS 980801WETLAND MITIGATION REPORT
STRATFORD MANOR DEVELOPMENT
U.S. Army Corps of Engineers
Project Number 1997-00423
Prepared for:
Brentwood Builders, Inc.
P.O. Box 702468
Dallas, TX 75370-5492
Prepared by:
Ge.o-Marine, Inc.
Environmental Engineering Services
550 East Fit~eenth Street
Piano, Texas 75074
AUGUST 1998
Dominant Plant Species
Table 2-1
Vegetation Present in the Northern Wetland
Indicator Stratum Other Plant Species Present (<1%) Indicator Stratum
1. Ulmua crassiflolia FAC T
2. Celtis laevigata FAC T/S
3. Aster praeaitus FACW H
4. Opuntia sp. - H
5. Stipa ieucotricha - H
6. Ruellia nudiflora UPL H
7. Bromus unioloides - H
8. Bromusjaponicus FACU H
9. Limnodea arkansana - H
10. Cyperus rotundus FAC H
H = Herbaceous
S = Shrub
T = Tree
1. Fraxinus pennsylvanica FACW- T
2. Cephalanthus occidentalis OBL S
3. Elymus canadensis FAC+ H
.Presley Hatcher indicated that hydrology was the primary parameter of the wetland delineation
for this site. He also explained that the vegetation had been altered primarily due to the
extensive agricultural history (i.e., grazing and mowing practices); therefore, the 7egetation was
not a good parameter of wetland status on this site. He further indicated that the soils met the
hyddc criteria due to two factors - being Trinity clays and their position within the landscape.
3.0 ~ AVOIDANCE, bHNI3iIZATION, AND UNAVOIDABLE IMPACTS
.~'[~ee purpose of the Stratford Manor Development is to construct a residential development and
an adjacent park. The residential development will occupy the majority of the southern portion
of the 15-acre site. The park will be located on the northern section between the residentiak
development and Denton Creek (see Appendix A - Figure 4). The residential development will
provide 29 single family housing units. The proposed park is part of a master plan to develop a
green belt adjacent to Denton Creek. This park will be contiguous to the existing park 'on the
east and the proposed park on the west. The only improvements to this park will be a nature trail
on the northern boundary of the property which will connect to the existing trail on the eastern
park.
Through the process of designing the residential development, several plans were considered in
order to minimize the impacts to the natural resources. Due to the orientation of the wetlands,
developing the site to completely avoid the wetlands would not be feasible. Minimization of the
impacts to the wetlands was the next approach. The original development consisted of 31 single
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family units with large lots. To avoid impacting a portion of Wetland B, two lots were
abandoned and the remaining lots were reduced in size. The second minimization was achieved
by ~_ereasing the depth of the lots to aeeomodate two green belts, oriented north-south, adjacent
to the eastern and western property lines (see Appendix A - Figure 4). Through these
minimization merles, a total of 0.855 acre of wetlands was avoided. The current development
plan would impact 1.47 acres of wetlands through the development of 12 acres for 29 single
family units.
The next in the process includes compensating or.m!tigafing for the 1.47 acres of wetlands that
will be unavoidably impaete& The following e_0neeptugl mitigation plan will create additi_onal
wetlands .to compensate for the wetland functions and values lost by the construction of the
residential development, in addition to enhancing 0.5 acre of the existing wetlands, so ,that
negative impacts will not occur to local hydrology, upstream and downstream aquatic resources,
and wildlife habitat. The 1.47 acres of created compensatory wetlands and the 0.5-acre wetlan~
enhancement area .will b__e__ d.e_ed .restric. ted to the home owners association so that the wetland
mitigation project will remain in perpetuity.
4.0 MITIGATION PLAN
To develop an appropriate compensatory mitigation plan, the existing wetland functions and
values need to be addressed so that they can be incorporated into the proposed plan. Secondly,
the plan needs to address the location of the mitigation site and characterization of the land use
history, dominant vegetation, local hydrology, and soils. Then, a conceptual mitigation plan is
developed using thisinformation. This mitigation plan addresses how the proposed wetlands are
appropriate compensation for adverse impacts to the existing wetland functions and values.
Finally, a monitoring plan is developed so that the mitigation plan will continue to be a success
without future maintenance.
4.1 DESCRIPTION OF EXISTING WETLANDS
The existing wetlands were a result of recent development within the surrounding area. Both the
properties to the east and west have been filled in for development purposes. Due to the adjacent
conditions, heavy clays, variable water depths, and are local to the north-central Texas area
(Table 4-1). However, a modified species composition may be necessary depending upon the
availability at the time of planting. Planting will not occur until the spring, after all earthmoving
activities are completed.
Table 4-1
Species Composition of ]~erbaceons Vegetation to be Planted
Species Composition
Paspalum spp. (floridanum, plicatulum, setaceum)
Panicum spp. (virgatum, dichotomiflorutn)
Setaria spp. (geniculata)
Carex spp. ( tribuloides, amphibola, crus-corvO
Cyperus spp. ( esculentes)
Eleocharis spp. (parvula, microcarpa)
Juncus spp. ( torreyi, effusus)
Eryngium spp. ( hookeri, leavenworthiO
$agittaria spp. ( latifolia)
Total
5%
10%
5%
15%
15%
10%
15%
5%
20%
100%
Planting trees is not being considered as a part of the mitigation plan due to the abundance of
existing mature trees (greater than 50 trees) in the mitigation site. Numerous trees will rapidly
sprout within the site following the cessation of th~ heavy grazing that currently exists on the
property.
4.5 MONITORING AND SUCCESS CRITERIA
During the development of the proposed wetland mitigation project,~ all c~mponents need to be
monitored to ensure success of the mitigation site. Secondly, a-4nonitoring plan will also
determine when the wetland is functioning without any further human intervention. The site
should be monitored by qualified biologists for the success of vegetation establishment on an
annual basis for at least five years until the success criteria are met. However, during the two
years after the wetland is planted, the site should be monitored during the dry seasons to
determine the need for irrigation. Irrigation to this site should be performed, as necessary,
during these dry seasons. ~._tailed annual monitoring reports .will be submitted to the USACE
summarizing the events of the mitigation project (i.e., additional planting, grading), mortality of
the vegetation, and proposed future events on the mitigation site (i.e., additional planting). To
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