2016 WORKSHOP Field Trip 1: Stream Xing

1. Bankfull discussion/Exercise: Attendees will have an opportunity to access two streams in several locations to look at bankfull indicators and measure bankfull channel widths. Phil Thomas from Trout Unlimited will be available to provide guidance and assistance.

2. Potosi Road: Completed LVR worksite. Work involved raising road profile above base flood elevation with permeable fill to disperse runoff, eliminated roadside ditch, armored streamside road edge to prevent road material loss to wetlands, and adjusted road intersection grades.

3. Blymire Hollow Road: Completed DGR work site. Existing 12 ft. wide bridge was closed to traffic in

2014 due to footing scour, undermining and wood deck and abutment deterioration. Bridge was replaced with a Stream Crossing Policy compliant 24 ft. wide span Geotextile Reinforced Soil – Integrated Bridge System (GRS-IBS). The new bridge reopened the gravel road to public use, improved public safety, reduced environmental impacts to the stream. Abutment installation was completed by township employees, and the bridge deck was manufactured off-site and set with a crane. The GRS-IBS system saved the township approximately 50% of the total project value over a conventional box-span bridge.

Note: These projects are not CDGRS demonstrations, rather they are all DGLVR Program projects funded by the local Conservation District. We extend our thanks to the York County Conservation District for allowing us to be involved in project implementation and for their willingness to share these sites with everyone.

Bankfull Exercise

Petosi Road

Blymire Hollow

Bankfull Exercise

The purpose of this exercise is to become more familiar with bankfull indicators and details of measuring the bankfull width of a channel. You will have plenty of time, so feel free to explore different sections of both streams to look for different situations, and ask questions of other attendees and Center and TU Staff. All surrounding property is owned by the County. Special thanks to the PA Chapter of Trout Unlimited and Phil Thomas for their help with this session.

Included in the following pages are: - NEW DGLVR Bankfull determination guidance sheet - Two DGLVR bankfull evaluation sheets

Potosi Road York County: Completed LVR Site Completed LVR worksite in North Hopewell Township funded by the York County Conservation District in 2015. $37K contract and $8K in-kind to raise the road with permeable fill and address drainage concerns.

Before: Poor road base/surface, frequent flooding. Problems:

• Subsurface water: springs, seeps and wetlands • Road surface drainage; potholes, wash boarding • Roadside ditch unstable • Cutslopes/fillslopes unstable • Bituminous cracking; edge deterioration; rutting

Solutions: • Permeable fill (~18”) • Outsloped road surface • Eliminated downslope ditch • Rock buttress along road edge • Pavement paid for by township.

During: road base improved, ditch eliminated, outsloped.

After: Road elevated, outsloped, and paved. Project Benefits:

• Permeable fill (18 inches) improved road base and maintains natural wet meadow hydrology (vs pipes) • Outsloping road surface eliminated ditch and disperses flows • Rock buttress along road edge provides resistance to floodwater erosion and slumps • Raised road surface above Base Flood Elevation • Less maintenance, ice issues, salts used, etc. with elevated road base.

Work Site

Road profile raised 18 inches; rock armor along road edge

Road grade adjustments

Wet ditch

Bituminous cracking, raveling and rutting

Edge deterioration

Wetlands Roadway floods

Blymire Hollow Road York County: Active DGR Site The 2016 funded work on Blymire Hollow was to replace a failed 12’ wide bridge with a 24’ Geosynthetic Reinforced Soil–Integrated Bridge System (GRS–IBS). GRS-IBS is an innovative bridge system that reduces bridge construction time and cost by utilizing compacted aggregate fill, geotextile and concrete blocks to construct the abutments, and then a bridge deck is set on the abutments. By utilizing commonly available and easy to work with materials, the Township was able to construct the bridge within weeks using Township labor. The only part of the project that was contracted was the construction and final setting of the bridge deck with a crane. See following page for more general info on GRS-IBS. Project costs were: $102,604 grant + $55,862 in-kind = $158,466 Total Project Cost

Before: Undersized, unstable footers, closed to traffic

During: GRS-IBS Abutment, aggregate layer compaction

Problems: • Failed township bridge closed to traffic in 2014 • Concrete/stone footers failed & undermined • Wood Deck deteriorating • Streambed scour, bank erosion, stream flow

impediment • Head and endwall integrity compromised

Solutions: • Replace existing bridge with bankfull width GRS-

IBS structure. • Stabilize stream banks and channel with plantings

and seeding & mulching.

During: GRS-IBS Abutment, geo-textile layer placement

During: GRS-IBS Abutments Project Benefits:

• Roughly 50% cost savings versus traditional structure. • Reduce scouring, streambank erosion and sediment loading to East Branch Codorus Creek (HQ-CWF/MF) • Bankfull structure width – greater flow capacity, aquatic organism passage. • Reopen gravel road to traffic for improved public safety and use.

Reb blocks are solid, and will provide visual reference for scour

Geosynthetic Reinforced Soil (GRS) Bridges

What is GRS-IBS? Instead of conventional bridge support technology, Geosynthetic Reinforced Soil (GRS) Integrated Bridge

System (IBS) technology uses alternating layers of compacted granular fill material and fabric sheets of geotextile reinforcement to provide support for the bridge. GRS also provides a smooth transition from the bridge onto the roadway, and alleviates the "bump at the bridge" problem caused by uneven settlement between the bridge and approaching roadway. What are the major advantages of GRS IBS?

GRS IBS offers unique advantages, particularly in the construction of small bridges. Construction costs are typically 25 to 60 percent lower than conventional construction methods. GRS IBS bridges are easy to build with common equipment and materials, so projects can be completed more quickly. They are also easy to maintain because they contain fewer parts: IBS is typically built without many of the elements common to a conventional bridge abutment, such as a bridge seat, bridge bearings, deck joints, approach slab, end wall, and sleeper slab. Its flexible design can be easily modified in the field for unforeseen site conditions, including unfavorable weather conditions.

More information from FHWA: http://www.fhwa.dot.gov/everydaycounts/technology/grs_ibs

Bank Full Width

"corresponds to the discharge at which channel maintenance is the most effective, that is, the discharge at which moving sediment, forming or removing bars, forming or changing bends and meanders, and generally doing work results in the average morphologic characteristics" (Dunne and Leopold, 1978)

.__ _______ topographic floodplam --------+

-c: hvdrologic floodplain >

bankfull ~a. • """e: elevatron

Stream Comdor Restorat1on: Ptmciples. Processes. and Pract1ces. 1998. Federal Interagency Stream Restora/lon Working Group.

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