erosion and sediment control plan

Erosion and Sediment Control Plan

Brizzolara Creek

MNMS Erosion Consultants 1 Grand Avenue

San Luis Obispo, CA 93410

Mary Hillis [email protected] Nico Navarro [email protected]

Mackenzie Taggart [email protected] Sarah Treadwell [email protected]

Table of Contents 1. Introduction

1. Introduction to Brizzolara Creek Erosion & Sediment Control Plan 2. Goals and Objectives 3. Regulatory Requirements of the Proposed Project

2. Site Assessment

1. Aerial Map of Brizzolara Creek Site 2. Produced Map of Brizzolara Creek Site Depicting Project Plans 3. Site Description

1. Soils, Vegetation, Landscape 2. Sources of water and sediment 3. Site Measurements 4. Evaluation of erosion

3. Erosion and Sediment Control: Best Management Practices

1. J-‐Hook 2. Riprap 3. Erosion Control Netting 4. Bioretention Planters

4. Maintenance and Inspection Procedures For Project

1. Schedule of procedures and planned inspections 2. Description of Maintenance: J-‐Hook 3. Description of Maintenance: Riprap 4. Description of Maintenance: Erosion Control Netting 5. Description of Maintenance: Bioretention Planters

5. Certifications and Notifications 6. Conclusion 7. References

1. Introduction 1.1 Introduction To Brizzolara Creek The purpose of this project is to mitigate channel erosion at the stream meander north of Engineering IV building on the California Polytechnic State University San Luis Obispo, CA. The outer bank of the stream meander has been laterally eroded, leaving unstable slopes that threaten the adjacent faculty parking lot and the overall channel health. In addition to the lateral erosion, additional problems exist that are a detriment to the channel health. The main channel problems include:

• Lateral erosion of outer bank • Sedimentation • Destruction of aquatic habitat and terrestrial vegetation • Metal scrap waste embedded in outer bank

1.2 Goals & Objectives This project will focus on:

• Stabilize the eroding outer bank • Centralize stream flow • Remove scrap metal along stream bed and outer bank • Improve overall quality of channel

1.3 Regulatory Requirements of Proposed Project There are three main agencies that have jurisdiction over amendments made in Brizzolara Creek. These agencies and their jurisdiction are explained below. California Department of Fish and Wildlife (CDFW): It is necessary to notify the (CDFW before undergoing streambed alteration. Under the Fish and Game Code 1602, it is necessary to notify the CDFW if any alterations are made to a stream. After notifying the CDFW, a Streambed Alteration Agreement must be made to permit activity. The agreement process in with the CDFW must comply with the California Environmental Quality Act (CEQA). The lead agency (local or state agency with approving authority), which can be the CDFW, must make sure the alteration complies with the CEQA. Aside from contacting the CDFW it is also important to determine of local permits are necessary and if the project is under the jurisdiction of federal and state agencies (CDFW, 2014).

US Army Corps of Engineers (USACE): In the case of of stream alteration the movement of materials within the streambed requires a USACE 404 Nationwide Permit (VCPD, 2006). This permit falls under section 404 of the Clean Water Act (CWA), which regulates discharge of dredged or fill material into the water of the US (EPA, 2014).

Regional Water Quality Control Board (RWQCB) : A 401 Certification from the RWQCB is necessary when obtaining a USACE 404 Permit. This permit falls under section 401 of the CWA which declares that each state must certify that the federally permitted activities (in this case issued from the USACE) are in compliance with all state water quality standards (VCPD, 2006).

2. Site Assessment

2.1 Aerial Map of Brizzolara Creek Site

Brizzolara Creek Project Site

2.2 Produced Map of Brizzolara Creek Site

2.3 Site Description The Brizzolara creek site is located northeast of the California Blvd and Highland Dr intersection on the Cal Poly campus. The vegetation includes mainly willows and eucalyptus trees with some herbaceous vegetation sprouting along the streambed and higher up on the banks. The streambed along the northern segment of the site is exposed bedrock, while the southern section consists of mainly cobbles three to five inches in width. The creek is currently dry, however runoff from previous events has caused significant erosion on the outer edge of the stream meander, along the northern bank. This past erosion is evident through the steep and mostly unvegetated northern slope adjacent to Highland Dr. In addition, there is a high percentage debris embedded in the northern bank of the stream channel. The southern bank, which represents the inside of the meander, displays a significantly lower relief than the northern slope and is highly vegetated.

2.3.1 Description of Soils and Vegetation The soils at the Brizzolara Creek site are classified as silty clay loam, and are part of the Salinas soil series. These soils formed from alluvial parent material deposits from weathered sedimentary rock. The soil is well drained thanks to its composition and is part of hydrologic soil group C. The K-‐factor for this soil is .32; this is a relatively high soil erodibility factor and is due to the high content of silt, which is easily eroded. The average annual temperature in this area is 68-‐70 degrees Farenheit and the average annual precipitation is around 23.45 inches

2.3.2 Sources of Water and Sediment There are three main culverts that drain into Brizzolara Creek site within the designated project area. These culverts supply water runoff and sediment from: an unpaved road running alongside the creek upland from the southern bank, roof drainage from engineering building 192, and the parking lot adjacent to the creek. These culverts funnel sediment and debris from the three sources straight into the creek, and pose a problem for the sensitive habitats of Stenner and other San Luis Obispo creeks downstream of Brizzolara. Runoff and discharge from the Horse Canyon Watershed also contribute to the water and sediment levels of Brizzoalra Creek.

2.3.3 Measurements of Site The designated watershed area contributing runoff and erosion at the Brizzolara Creek site is approximately 3.2 square miles. The measured streambed length at the project site is 49 feet. The average width of the streambed is 10.5 feet, and the average depth of the channel is 6.5 feet, yielding a cross sectional area of 68.3 square feet.

2.3.4 Evaluation of Erosion and Sediment Delivery Field measurements of features were taken at the project site and used to calculate BEHI and Shear Stress ratings. The bank erosion rate for current and future conditions was then calculated based on these ratings:

Current Condition: Brizzolara Creek is currently eroding on the northern slope of the channel. This slope exhibits a steep grade, a low percentage of surface protection, and a shallow rooting depth for vegetation. Based on these observations and an assessment of bank materials, the initial BEHI calculation resulted in an “extreme” rating for the hazard of bank erosion. Similarly,

the initial rating for Shear Stress also resulted in an “extreme” rating. Based on both the initial ratings, the determined bank erosion rate is 2.8 ft/yr.

Future Condition Without BMP’s: When calculating the predicted future BEHI and Shear Stress ratings for the area of interest, it was determined that most of the channel conditions would remain constant. The foreseeable changes are a higher relief on the northern slope as it continues to be affected by lateral scour and a smaller a decrease in surface cover. Based on these conclusions, the BEHI and Shear Stress ratings the are also rated “extreme”. The continually degrading conditions result in a slightly higher bank erosion rate of 2.9 ft/yr.

Future Condition With BMP’s: The proper installation of Best Management Practices (BMP) will help to improve channel conditions and consequently decrease the bank erosion rate. The BMP’s utilized will reduce the slope of the banks, increase surface protection, and reduce the near bank maximum depth. These improvements will reduce both the bank erosion hazard and shear stress ratings to low, resulting in a bank erosion of .04 ft/yr.

3. Erosion and Sediment Control: Best Management Practices

3.1 Overview of BMP’s and Implementation at Project Site Numerous Best Management Practices (BMPs) will be used to divert stream flow, decrease stream bank erosion, create habitat for wildlife, and beautify the Brizzolara Creek site. A J-‐hook will be secured slightly upstream from the highly erosive north bank of the Brizzolara Creek bank, diverting flow away from the outer portion of the stream meander. The large, inactive, concrete culvert feeding into the creek will be taken out and replaced with logs and riprap on the creek bed to protect the bank. The use of riprap along the northern bank will prevent further downward erosion of the streambed in this area, and will stabilize the slope, preventing scour of bank materials and loss of sediment. Excavating the highly eroded stream bank will be the first of many BMPs applied to the unstable, highly eroded stream bank. Cutting the near vertical slope back to a grade of 1:1, 45-‐degree angle will decrease the chance of mass wasting and sediment erosion. While excavation equipment is in the creek, the rusting iron debris will be removed. Following grade control on the north bank, a series of BMPs will be implemented in order to insure its stability and is conducive to wildlife

Initially, a layer of compost two inches thick will be raked evenly on the stream bank. Seed will be incorporated into this thick, woody mixture to cut cost and simplify the application process. Compost was chosen because it improves soil quality, protects the ground from splash erosion, and provides plants with nutrients overtime (Caltrans, 2014). The seed mix will contain native grasses, forbs, and legumes (Caltrans, 2010). Succeeding the compost, a layer of Coconut Netting will blanket the stream bank, secured with pins. This rolled erosion control product is available in several strengths; Type B will be sufficient considering the weight of mat and the amount of space left open in the weave. A coconut fiber mat was chosen for its ability to withstand a 1:1 embankment, degradable material, retention of soil moisture for germination of seeds, and safeguard soil from erosion (Caltrans, 2014). Willow Cuttings will then be planted systematically

along the bank through the open spaces in the netting. Willows, native to the area, thrive in stream communities providing long-‐term strength of not only the riverbank, through extensive root systems, but also in offering animal habitat (WVDEP, 2014). Plantings of a variety of other native shrubs and grasses within the willows and coconut mat structure will finalize the efforts taken to assure the once eroded Brizzolara stream bank is stable for years to come. On the top of the bank, bioretention planters will be utilized to divert, hold, filter, and infiltrate stormwater running off of impermeable surfaces such as the adjacent parking lot all while creating an aesthetically pleasing environment.

3.2 J-‐Hook A j-‐hook is a structure used to redirect stream flow for urban stream repair purposes. The j-‐hook is an upstream directed, gently sloping structure consisting of natural materials including but not limited to boulders, logs, and root wads or a combination of materials. The structure is placed at a 20 to 30 degree angle on the outer bend of the stream meander where the highest stream velocity occurs (Rosgen, 2014). There are two sections of the j-‐hook, the vane and the hook. The vane consists of the straight section that covers approximately ⅓ of the banfkfull width. No gaps exist in the structure on the vane section. The hook section consists of the curved section of the structure. Small gaps exist in the hook section. The j-‐hook helps to reduce bank erosion along the stream bank toe by centralizing flow. Centralizing flow helps to mitigate stream bank erosion by reducing near-‐bank slope, velocity, and shear stress. The j-‐hook is effective to three times its length. As the water travels downstream, the j-‐hook forces the flow towards the center and allows the shear stress to be concentrated in the center of the channel. The vane helps creates a scour pool downstream. The hook section works in conjunction with the vane section by creating a longer, deeper, wider pool. The gaps within the hook section create a vortex flow pattern that further helps to centralize flow and increase transport of sediment and debris (Schueler and Brown, 2014). The increased depth helps the stream accommodate larger floods, increases cross-‐sectional area, and ultimately helps reduces bank erosion.

3.3 Riprap At the Brizzolara Creek site, the creek takes a tight right before continuing downstream of the area of interest. This turn concentrates the energy of the creek directly at the Northern bank before it can continue around the turn, and results in serious erosion and instability of the bank and the streambed. The BMP we will use to stabilize the streambed and lower bank from further erosion is riprap.

Riprap is the use of large stones placed in a layer over or under a specific area to prevent soil erosion due to concentrated runoff (NPDES, 2014). Riprap can be effective for stabilization on slopes as well, however it can also become unstable under certain conditions, such as using rounded rocks, or with slopes steeper than 2:1 (FHWA, 2014). In order to ensure the successful implementation of riprap, there are some guidelines that must be followed, these include: using a durable stone in various rock sizes, ensuring your riprap layer extends deep enough to two times the maximum stone diameter, and placing the riprap high enough along banks above the maximum flow depth (NPDES, 2014). At our site, we will dig out an area about eight feet in length and five in depth along the base of the Northern bank where the creek follows the turn; we will then fill the

area with a layer or rip rap and backfill the area with the displaced soil. This underlying layer of riprap will serve as a toe protection along the base of the Northern bank, and will prevent the further downward erosion of the streambed by the creek and it follows the sharp turn. The riprap will be continued upward two feet in height above the streambed to provide for extra stabilization of the bank. Riprap serves as a cost effective, durable solution for stabilizing this small area of our project.

3.4 Erosion Control Netting

The rolled erosion control netting product is made of 100% coconut fiber woven into a checked pattern. It is produced in three different strengths; Type B, as defined on Caltrans, will be sufficient considering the weight of the mat (700 grams/sq. meter) and the 50% open space left in the weave. Type B netting will be effective up to a 1:1 slope unlike counter products such as Jute or even Type A netting. Coconut netting lasts up to three years, giving the willows and plants substantial time to become established. A limitation to rolled erosion control options is their expense. However, 200 square feet maximum would be the needed, rounding out the cost under $190 (Caltrans, 2014) Benefits of the netting include:

• Provides immediate protection of the soil while plants are still young. The weave is slightly tighter than many woven mats, allowing a greater stability of the slope at early, vulnerable stages.

• The Natural fibers retain soil moisture, improving the germination of seeds and plant growth (Caltrans, 2014). This is a necessity in the dry climate of the Brizzolara Creek.

• Many erosion control rolled products are partial produced with synthetic material. This netting is fully biodegradable, a key in a self regulating, natural environment.

The application of netting follows a similar process to other rolled erosion products. Begin with digging an anchor trench 6 inches deep at the top of the slope, the length of the bank wished to be covered (McCullough, 2014). Place the first 4 inches of the netting in the trench and secure with metal U pins 2 feet apart and cover with soil. Roll out the track working downhill a few yards at a time. Catch the roll using wooden stakes so adjustment to the tautness and securing of the netting can be made easily. Drive in U pins every 3 feet in a diagonal pattern. Once the roll netting has covered the entire slope, make an anchor trench identical to the anchor head. Staple 4 inches of excess netting into the trench before cutting it off from the roll. Finally, burry and compact the trench with soil.

3.5 Bioretention Planters

The Brizzolara Creek Site Project lies adjacent to an older staff parking lot across Highland Drive from building 192: Engineering IV (see Figure 1. location map). Runoff from the parking lot into Brizzolara Creek occurs in the upper east portion on the north bank where asphalt erosion is evident. Following the erosion control BMPs executed on the north bank of Brizzolara Creek it will be important to control runoff coming onto the bank from the parking lot area in order to maintain structural integrity. Stormwater/bioretention planters utilize soil and plants to infiltrate, slow, and clean stormwater coming off of impervious surfaces (Central Coast LIDI, 2014). Stormwater runoff from the adjacent staff parking lot will be diverted into the bioretention planters where it will be temporarily held, filtered, and infiltrated into the

surrounding substrate. Excess runoff exiting the planters into the creek bed will be slower and cleaner as a result (Caltrans Erosion Toolbox, 2014).

Some general parameter of parking lot Bioretention Planters include:

• The recommended depth of soil in the planters is 24 inches with an underdrain, although 18 inches is the legal minimum.

• Curb height and gutter width are also recommended to be 24 inches -‐ providing additional structural support.

• Maintain a 6” wide “bench” of native soil at the sides of the planters to maintain sidewalks stability.

• A layer of filter fabric is used between the topsoil layer and the bottom aggregate layer. This allows the aggregate layer to store additional stormwater apart from water stored in the soil layer

3.6 Evaluation of Future Erosion The current bank erosion at the Brizzoalra creek site is 2.8 ft/yr, with estimated future erosion to be slightly higher at 2.9 ft/yr. Through the use of the identified best management practices, the future erosion of Brizzolara creek will be reduced to .04 ft/yr. The bank erosion hazard and shear stress will also be significantly decreased after BMP implementation, with a new rating of low for both.

4. Maintenance & Inspection of BMP’s

4.1 Maintenance & Inspection of J-‐Hook J-‐hooks are generally a sturdy BMP and require low levels of maintenance. Problems such as sediment or debris accumulation behind the hook can occur, which could cause damage to the hook and reduce its effectiveness. For best results, the J-‐hook should be inspected after heavy rainfall and once monthly. If accumulated material is present, they should be removed, and any damage caused should the j-‐hook should be remedied right away. 4.2 Maintenance & Inspection of Riprap In order to maintain the integrity of the riprap, the area will be inspected at minimum once a year to survey damages and necessary management. The riprap will also be inspected after large storms where excess rainfall may have caused damage to the integrity of the riprap. (NPDES, 2014) Riprap when implemented according to the proper guidelines, is a relatively sturdy BMP and will not require minimal maintenance. If the riprap structure is damaged, it must be repaired promptly before the creek can cause more damage. If it becomes clear the riprap continues to be damaged in a particular spot of in a particular way, measurements of our area of interest will be taken and the design of the riprap implementation will be reevaluated. Changes will be made in regards to the new findings of inspection. At our site we plan to integrate the use of other BMP’s such as Willow stakes and brush mattresses along with our implementation of riprap. These other management practices will ensure the stabilization of the upper bank slopes as well as protect the soil surrounding the riprap.

4.3 Maintenance & Inspection of Erosion Control Netting Project will be completed around late summer. This allows the system time to become established before the rainy season. In the weeks following the development, inspection of the stream bank includes: netting is still secured, seeds are germinating, and willows and other vegetation are taking root. This will also include irrigation of the plants if little precipitation falls, until they become more mature. After heavy rain events visual checks should be made to the netting to ensure none has come loose. After a few months of careful watch and potentially watering, the vegetation should be established and the bank protected and self sustaining.

4.4 Maintenance & Inspection of Bioretention Planters Perennial plants and trees will need some irrigation during the dry season (June-‐October in San Luis Obispo). Average watering schedules for mature established plants and trees is approximately weekly with 1” of water per application. Drip irrigation inspections should be conducted routinely to make sure that water is being used efficiently without waste. Reservoirs receive water prior to infiltration and should be maintained for clogging. Inspecting for debris and sediment pre and post wet season should be conducted during the month of May, and again in October. Sand, gravel, and topsoil allow stormwater to percolate uniformly through the planter. Inspections and maintenance should focus on any holes that are not consistent with the system to prevent water from flowing directly through the planter. Also, litter and debris shall be removed during inspections. Inspections should be conducted prior to and directly after the wet season in May and again in October. Any cracks or failure spots should be repaired throughout the year during regular inspections.

5. Certifications & Notifications I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gathered and evaluated the information system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine imprisonment for knowing violations.

___________________________________ ____________________________________ Mary Hillis 5th June, 2014 NIco Navarro 5th June, 2014

___________________________________ _____________________________________ Mackenzie Taggart 5th June, 2014 Sarah Treadwell 5th June, 2014

6. Conclusion The main issues of erosion and sedimentation will be remedied through the proper installation of a riprap, j-‐hook, rolled erosion control, and bioretention planters. Bank erosion is predicted to decrease from 2.8 ft/yr to .04 ft/yr with the installation of these BMP’s. This alteration will help to create a stable channel and slope; sustainable habitat for aquatic species and terrestrial vegetation; and add aesthetic value. The alteration will create a site that will enhance the environment and moreover the overall channel health. 7. References

Caltrans. 2010. Key concepts of sustainable erosion control: technical guide. pp.24-‐32. https://polylearn.calpoly.edu/AY_20132014/pluginfile.php/439729/mod_resource/content/2/Erosion_Control_Technical_Guide_v2.pdf. May 29,2014. "Clean Water Act, Section 404." EPA Regulations. EPA, n.d. Web. 06 June 2014. <http://water.epa.gov/lawsregs/guidance/wetlands/sec404.cfm>. "EPA -‐ Stormwater Menu of BMPs." NPDES, 31 July 2013. Web. 22 May 2014. <http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm?action=browse&Rbutton=detail&bmp=39>.

FHWA (Federal Highway Administration). 1995. Best Management Practices for Erosion and Sediment Control. FHWA-‐SLP-‐94-‐005. Federal Highway Administration, Sterling, VA "Lake and Streambed Alteration Program." Questions and Answers. California Department of Fish and Wildlife, n.d. Web. 03 June 2014. <http://www.dfg.ca.gov/habcon/1600/qa.html>. "Rolled Erosion Control Product (Netting)." Erosion Control Netting. Caltrans, n.d. Web. 06 June 2014. <http://www.dot.ca.gov/hq/LandArch/ec/recp/ec_netting.htm>. Rosgen, D.L. 2014. The cross-‐vane, w-‐weir and j-‐hook strcutures… their description, design and application for stream stabilization and river restoration. Wildland hydrology. Web 06 June, 2014 < http://www.wildlandhydrology.com/assets/cross-‐vane.pdf> Schueler, T., and K. Brown. 2014. Urban watershed restoration manual no. 4: urban stream repair practices(version 1.0). West Virginia Department of Environmental Protection. 06 June, 2014. <http://www.dep.wv.gov/WWE/Programs/stormwater/MS4/guidance/Documents/Manual%204%20Urban%20Stream%20Repair%20Practices%202004.pdf>