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Reports on potential Natural Stream Design Projects 1. Butternut Creek/ Richard Hillary Property 2. Briar Creek / Al Hewlett Property 4. Otsego Creek |
| Site #1 - Butternut Creek / Richard Hillary Property
Findings -- This segment viewed on the Hillary Property appeared to be in good condition. The stream type was a C4 within a valley type VIII. The vegetation throughout the area also appeared to be in good condition and of appropriate type to assist in holding the stream together. Some banks along the segment were somewhat raw. This appears to be normal. Streams naturally erode, at what rate they erode is of concern. The system needs sediment to dissipate energy and it will take it from the bed as well as the banks. In our brief visit to the site, it appeared that the rate was not great enough to bring up concern. Although to make certain of this observation, it is possible to measure the rate of erosion by installing permanent monumented cross-sections. This could be done very cheaply and it would only take someone’s time to initially set up the monitoring and at a minimum it would only have to be re-surveyed once a year to achieve an annual rate. You may want to locate any developed bank erosion rate curves for your region. As for the section of this segment that is braided, the D channel, it is not of much concern either. It appears from the topographic and infrared maps that the D channel is at the end of a pinch or a tightening in the access of floodplain area. The vegetation and the valley cause this pinch. The areas just below or at the pinch usually can display a different stream configuration. The change in configuration is due to the limited floodplain access. Therefore, it is typical for the stream to display this behavior and it appears that it is causing no harm.
Recommendations -- The recommendations for this site is to leave it go for now, but take the initiative to watch it and learn from its behaviors through the use of the permanent cross-sections.
Additional Information -- Three different developed regional curves show approximate potential parameters for this watershed size of (18.2 mi2). Northeastern PA Glaciated Low Plateau Section Eastern U.S. Width 50 ft 57 ft 45 ft Mean Depth 2.6 ft 2.6 ft 3.6 ft Area 100 ft2 160 ft2 160 ft2 WxD 130 ft2 148 ft2 162 ft2 *Note there is some discrepancy in the area calculation value compared to the graph value. *These data were not developed for this region and are approximate values for all stream types. This data it to be used as reference only. A typical normal (not necessarily geologic and also not accelerated) erosion rate for three different developed bank erosion rate curves might be: Colorado Yellowstone North Carolina Rate ft/yr .035-.25 .045-.4 .017-.2 *These data are shown to have an approximate rate of erosion that might be expected for a natural rate. Of course, this data was not developed for this region and should only be used as a reference. Digital references included with this report are:
A Glossary is included at the end of the Guidelines document.
Site #2 - Briar Creek / Al Hewlett Property
Findings and Recommendations -- There are many items to consider when addressing the stream instability along the segment viewed of Briar Creek. The current stream type appears to be a C4 in a valley type VIII. The appearance from the site visit and the map might indicate a sinuosity of 1.1, a width/depth ratio of 25, and alternates between aggrading and degrading sections with areas of bed and bank instability. The upper section of the creek (pasture area above the bridge) appears to be a possible candidate for Natural Stream Channel Design (NSCD). The general appearance is that the stream has lost capacity to carry its contributing sediment loading. In other words, the bankfull cross sectional area appears to be too small through this section. This may be an impact from the continual access of the channel to the cattle and their heavy traffic. Verification of this can be viewed in a longitudinal profile. The lack of vegetation has not helped the stream instability. Poor vegetation can lead to an over-wide, excess sediment loaded system. With the stream having the inability to move sediment appropriately, the channel may start to fill in causing the channel to shift. Any shift in the channel will cause it to ‘eat up’ additional material from the adjacent banks, ultimately adding more sediment to the system. Consideration for this section might be to monitor the channel and find out what processes are happening in consideration for NSCD and at a minimum would be to fence out the area with a reasonable riparian width, add controlled stabilized agricultural crossings, and plant with appropriate vegetation. The section just upstream of the bridge appears to require a hardening of the banks (i.e. riprap, gabion baskets, etc.) to ensure stability and to protect the farmer’s access road and the bridge. The appearance from the site visit might indicate that the bridge opening is the cause of the lateral migration and subsequent bank erosion in this area. The next section of consideration is the channel between the highway bridge and the railroad bridge. It appears that material is continually removed from this area. Actually, just as we left the area, walked downstream, and returned 15 minutes later, equipment had been in that section and some material was removed. The instability predominately appears to be from this type of activity. Consideration for remediation might include the re-establishment of the cross sectional area, addition of a couple J-Hook Vanes to alleviate the pressure on the bank, addition of a controlled stabilized agricultural crossing and riparian plantings. The downstream most section appears to be in reasonable condition. That is, a good enough condition as not to require any significant intrusions. The segment appears to have been ‘cleaned out’ at some point in time given the remnant berm. This activity probably has lead to some the current channel instability. Other factors include the influence of the cattle (pasture area), the lack of appropriate vegetation, and possibly the influence of backwater from the river. Possible remediation efforts for this segment may include installation of a few stabilized agricultural crossings, fencing out the riparian area, and planting vegetation. Possible funding sources for some of these segments may include USDA CRP monies.
Additional Information -- Three different developed regional curves show approximate potential parameters for this watershed size of (9.1 mi2). Northeastern PA Glaciated Low Plateau Section Eastern U.S. Width 47 ft 42 ft 35 ft Mean Depth 2.4 ft 1.2 ft 2.7 ft Area 60 ft2 90 ft2 95 ft2 WxD 113 ft2 50 ft2 95 ft2 *Note there is some discrepancy in the area calculation value compared to the graph value. *These data were not developed for this region and are approximate values for all stream types. This data it to be used as reference only. A typical normal (not necessarily geologic and also not accelerated) erosion rate for three different developed bank erosion rate curves might be: Colorado Yellowstone North Carolina Rate ft/yr .035-.25 .045-.4 .017-.2 *These data are shown to have an approximate rate of erosion that might be expected for a natural rate. Of course, this data was not developed for this region and should only be used as a reference. Digital references included with this report are:
A Glossary is included at the end of the Guidelines document.
Site #3 - Schenevus Creek
Findings -- Many things need to be observed, surveyed, and documented before even attempting to address the issues of this severity and extent on a fluvial system. Natural Stream Channel Design probably has application for this site, but so much information needs to be gathered before anything should be allowed to begin. This stream at this location is very large 86.4 + square miles (missing a large segment of the watershed). The current state of the channel is a C4 or E4 type in a VIII valley. A C channel has sinuosity >1.2 and a width/depth ratio > 12. The E channel has a sinuosity >1.5 and a width/depth ratio <12. Both stream types have slopes of <.02 and an entrenchment >2.2. The width/depth ratio is the factor that has me guessing on which stream type to choose. Without having the opportunity to perform a detailed cross-sectional survey, I would have to venture that the stream is entrenched and incised for either of the discussed stream types (excess stress). This has probably occurred due to some of the meanders being cut off and the stream being realigned for additional farm fields. The increased slope, due to the shorter length over the same drop, has increased the stream’s power. An overall change in the hydrology may have an impact as well. The erosion as readily seen on the banks (not so much in the bed now), predominately on the outside of the meanders, is evidence that the stream is moving laterally due to steepened slope (trying to now flatten the slope). The lateral movement is now aiding in the addition of floodprone width (the width as projected from an elevation from the bed at 2 x maximum bankfull depth). As it appears now the stream at this designated depth can not access the vast floodplain area.
Recommendations -- The short sum of it all is that the stream is unstable and monitoring needs to be installed to show exactly what is happening. Monitoring data will also aid in the potential design of a functional natural stream channel. If you wish to move forward in this endeavor and are looking for advice on setting up a monitoring plan, we can make ourselves available.
Additional Information -- Three different developed regional curves show approximate potential parameters for this watershed size of (86.4 + mi2). Northeastern PA Glaciated Low Plateau Section Eastern U.S. Width 77 ft 120 ft 85 ft Mean Depth 3.5 ft 3.5 ft 5.3 ft Area 320 ft2 410 ft2 450 ft2 WxD 270 ft2 420 ft2 450 ft2*Note there is some discrepancy in the area calculation value compared to the graph value. *These data were not developed for this region and are approximate values for all stream types. This data it to be used as reference only. A typical normal (not necessarily geologic and also not accelerated) erosion rate for three different developed bank erosion rate curves might be: Colorado Yellowstone North Carolina Rate ft/yr .035-.25 .045-.4 .017-.2 *These data are shown to have an approximate rate of erosion that might be expected for a natural rate. Of course, this data was not developed for this region and should only be used as a reference. Digital references included with this report are:
A Glossary is included at the end of the Guidelines document.
Site #4 – Otsego Creek
Findings -- The particular area where the riprap is located appears to be an effect from the possible channel work done upstream of the bridge and/or headcuts that have moved upstream from downstream reaches. If that were true, that would account for the down cutting of the streambed and the under-cutting of the placed riprap causing it to slide. The meander at this location appears to have too tight of a radius to hold for this current stream type. This may also be an effect from the removed vegetation on the near bank. The general overall appearance should paint a nice picture – a stable stream channel. That is given the valley and the vegetation within the riparian area. That is why this area is confusing without knowing any history and without the opportunity to further investigate the surrounding land. The additional damage seen on the downstream banks is probably attributed to the possible acts upstream or the movement of headcuts from downstream. The appearance, without the aid of a detailed cross section and historical data, is that the streambed has dropped and it is now creating a new floodplain at an elevation below the old floodplain. The stream appears to be quite far along this course, trending toward stability. Although at one time probably not too long ago the channel would have looked quite different. It would have shown signs of entrenchment and incision. Then this additional stress widened the channel and then recreated floodplains within the widened channel.
Recommendations -- At this time and without any additional information as to what has happened in this location, a recommendation is to install permanent cross sections and monitor the stream and remove the current debris blockages. The appearance of this segment is that it is in the process of healing itself.
Additional Information -- A typical normal (not necessarily geologic and also not accelerated) erosion rate for three different developed bank erosion rate curves might be: Colorado Yellowstone North Carolina Rate ft/yr .035-.25 .045-.4 .017-.2 *These data are shown to have an approximate rate of erosion that might be expected for a natural rate. Of course, this data was not developed for this region and should only be used as a reference. Digital references included with this report are:
A Glossary is included at the end of the Guidelines document.
Each of the previous four reports included the following notes and references:
Excerpt From The Guidelines For Natural Steam Channel Design For Pennsylvania Waterways What Makes a Successful Natural Stream Channel Design Project? Professionals engaged in successful natural stream channel design:
Successful stream corridor restoration depends on an understanding of how water and sediment are related to channel form and function and on what processes are involved with channel evolution. This is particularly important in the context of Pennsylvania's diverse geology. What works in the lowlands of southcentral Pennsylvania may not work in the glacial till streams of northeastern Pennsylvania or in streams impacted by coal mining. There can be no "one size fits all" design package for natural stream restoration. Data from the affected site and data from reference reaches and regional curves from the same physiographic regions and stream types are critical to designing channels that will not fail under the most frequent, channel-forming storm events.Successful projects usually involve teams that include biologists, hydrologists, and engineers who understand natural stream functions. Successful teams make the effort to evaluate reference streams in planning and designing restoration projects, and they consider multiple alternatives before deciding on the best approach for a given stream project. Most importantly, successful stream restoration requires that we all learn from past mistakes and avoid repeating them.Furthermore, natural stream channel design must allow for the integration of "unnatural" design features (traditional hard-engineering) on sites where adjacent land uses restrict efforts to work with a new or existing floodplain. Because natural channel design places great emphasis on connecting a stream with its floodplain, design options are limited in developed areas where lateral excavation of the streambanks is restricted. For more guidance on NSCD options, see Chapter 3 Meeting with the Watershed Community. Scope of GuidelinesThese guidelines are intended for stream channel restoration work only. For purposes of this guide, "restoration" is defined as "the process of converting an unstable, altered, or degraded stream corridor, including adjacent riparian zone and flood-prone areas to its natural or referenced, stable conditions considering recent and future watershed conditions. This process also includes restoring the geomorphic dimension, pattern, and NSCD Guidelines April 2002 1-4 profile as well as biological and chemical integrity, including transport of water and sediment produced by the stream's watershed in order to achieve dynamic equilibrium."In developing this document, much discussion centered on the application of these guidelines for projects considered "small-scale" or "remedial" in nature. After considerable debate, the Keystone Stream Team concluded that these guidelines should provide direction on restoration projects (as described above), which are usually of a larger scale than those designed to offer a more limited environmental or ecologicalbenefit. In other words, professional judgment is imperative in making the distinction between stream restoration projects and stream enhancement or stream stabilization projects.For purposes of this guide, stream enhancement is defined as "the process of implementing certain stream rehabilitation practices in order to improve water quality and/or ecological function." These practices are typically conducted on the stream bank or in the flood prone area but may also include the placement of instream habitat structures; however, they should only be attempted on a stream reach that is not experiencing severe aggradation or erosion. Care must be taken to ensure that the placement of instream structures will not affect the overall dimension, pattern, or profile of a stable stream.Stream stabilization is the in-place stabilization of a severely eroding streambank and streambed. Stabilization techniques which include "soft" methods or natural materials (such as root wads, rock vanes, vegetated crib walls) may be considered part of a restoration design. However, stream stabilization techniques that consist primarily of "hard" engineering, such as concrete lined channels, rip rap, or gabions, while providing bank stabilization, will not be considered restoration or enhancement in most cases. Some techniques provide both stabilization and enhancement. These include the placement of appropriate instream grade control structures and the establishment of appropriate stream bank vegetation.All situations should be evaluated on a case-by-case basis using the best professional judgment available. Meetings with the watershed community as described under Chapter 3 will help answer the question of what type of project you have. Regardless of scale, it remains critical to consider a site's larger watershed conditions and to have field-verified data to support even smaller stream restoration projects. Permit conditions, as explained in Chapter 5, provide further qualifications for projects that would fall under enhancement or stabilization categories.Specifically, these guidelines provide direction on the following topics as they apply to natural stream channel design:
These guidelines are not an endorsement of one methodology or tool to the exclusion of others due to the fact that the design of natural channels is a developing science. However, the Keystone Stream Team recognizes the increasing usefulness of Dave Rosgen's stream classification system and design methodologies. Conversely, the group recognizes the need to address the strengths and limitations of all restoration methodologies and attempts to explain some of these observations in Chapter 4 Data Collection & Analysis.Where approval has been granted, the guidelines refer users to various tools and methodologies and credits the originators of these tools. Included in this document are sets of tables, charts, and other forms that the Keystone Stream Team believes are most helpful in data collection & analysis. Use them at will. Forms can be duplicated for use in the field. See Appendix I.It is also important to note that the guidelines suggest a sequence of steps to get from planning to implementation. However, the exact sequence may vary depending on the person or group that has initiated the project and what type of information is already available. More important than the sequence is the attempt to cover the elements presented under each step so as not to overlook something altogether. Finally, it's important to stress that these guidelines are an evolving document and the result of collective experience by a wide variety of professionals. Content is based on what members of the Keystone Stream Team have learned about natural stream channel design in the field. It is the team's intention that these guidelines will serve to save practitioners time and money by avoiding mistakes in design and implementation. The content of the guidelines will change as more is learned through field experiences.
REMEMBER: Regardless of scale, it remains critical to consider a site's larger watershed conditions and to have field-verified data to support even smaller stream restoration projects. |