Stormwater Best Management Practices

Transcription

1 Stormwater Best Management Practices INVENTORY, INSPECTION, AND MAINTENANCE GUIDLELINES AUGUST, 2017 Maintenance Operations OHIO DEPARTMENT OF TRANSPORTATION

2 Contents I. Purpose...3 II. Stormwater Best Management Practices (BMP s)...3 Vegetated Biofilter...4 Vegetated Filter Strip...5 Manufactured System...6 Detention Basin...7 Retention Basin...9 Infiltration Trench...10 Bioretention Cell...11 Exfiltration Trenches...13 Constructed Wetland...14 Infiltration Basin...14 Underground Detention...14 Stream Grade Control...14 III. Initial Inventory and Inspection of Active BMP s...15 Vegetated Biofilter...16 Vegetated Filter Strip...17 Manufactured System...18 Detention Basin...19 Retention Basin...20 Infiltration Trench...21 Bioretention Cell...22 Constructed Wetland...24 Infiltration Basin...24 Underground Detention...24 Stream Grade Control...24 IV. BMP Maintenance...25 V. Annual Inspections...25 VI. Inventory and Inspection of Newly Constructed BMP s...25 VII. Appendix A (District Representatives)...26 District Hydraulic Representatives (August, 2017)...26 District TAM Coordinators (August, 2017)...26 District MS4 Liaisons (August, 2017)...26 VIII. Appendix B (Inspection Item/Maintenance Issue)...28 Check Erosion/Ruts/Gullies...28

3 Remove Sediment/Trash/Debris...28 Remove Woody Vegetation...28 Maintain Ditch Bottom...28 Grass Coverage 80%...29 Check Ponding...29 Inspect Bank & Overflow Weir...29 Inspect Outlet...29 Check Observation Wells...29 Check for Compaction...30 Add Mulch...30 Check Ponding...30 Inspect/Replace Diseased Plants...30 Mow Grass...30 Prune/Weed/Water Plants...30

4 I. Purpose The purpose of these guidelines is threefold. The first is to describe Stormwater Best Management Practices (BMP s). The second is to describe the initial inventory and annual inspection requirements for Active BMP s. The third purpose is to describe the acceptance process of BMP s from Construction to Maintenance responsibility. These guidelines provide a regular and systematic approach to aid in the inspection of these structures and to protect the public s investment through routine maintenance. ODOT districts are required to perform an initial inventory of Active BMP s to confirm their location, annually inspect and maintain (if required) these devices, and inventory and inspect BMP s as they are constructed on future projects (Proposed BMP s becoming Active BMP s). This manual is intended to be used as a supplement to the ODOT ESRI Collector Application. The Collector Application was configured by the Office of Technical Services. II. Stormwater Best Management Practices (BMP s) For purposes of these guidelines, a Stormwater BMP is a structural element designed to reduce the volume of runoff through infiltration practices and address storm water quality impacts from highway construction. There are many types of Stormwater BMP s used on highway projects in Ohio. Examples include: Vegetated Biofilter Vegetated Filter Strip Manufactured System Detention Basin Retention Basin Infiltration Trench Bioretention Cell Constructed Wetland Infiltration Basin Underground Detention Stream Grade Control Exfiltration Trench (no longer used in Ohio) The most common types of Stormwater BMP s constructed in Ohio are the Vegetated Biofilters, Vegetated Filter Strips, and Manufactured Systems.

5 Vegetated Biofilter Vegetated biofilters are trapezoidal channels that filter storm water via the interaction of vegetation with suspended solids in the storm water. It can be difficult to tell the difference between Vegetated Biofilters and regular grass ditch. Added to this, many Vegetated Biofilters look different on ODOT projects due to changing rules and inconsistent design and construction. Two ways to distinguish Vegetated Biofilters from ditches is to look for an erosion control mat or the plan drawings. However, erosion control mat may be installed outside of Vegetated Biofilters. A ditch with a wider bottom than typical for the area may also be an indication that it is a Vegetated Biofilter. Vegetated Biofilters need to be inspected and maintained for the following elements:

6 Vegetated Filter Strip A vegetated filter strip is a BMP that filters storm water through vegetation. The vegetated filter strip consists of the vegetated portion of the graded shoulder and the vegetated foreslope. The vegetated filter strip must be void of gullies, ditches, or concentrated flow. The water flow is characterized as overland flow throughout the grass. It can be difficult to tell the difference between Vegetated Filter Strips and regular grassed shoulders. Two ways to distinguish Vegetated Filter Strips from a normal shoulder and foreslope is to look for an erosion control mat or the plan drawings. However, erosion control mat may be installed outside of Vegetated Filter Strips. Further compounding this issue is many Vegetated Filter Strips in the current BMP database may be mislabeled and actually be Vegetated Biofilters.

7 Manufactured System Manufactured Systems consist of underground structures that treat surface water by removing particulate matter through fluid dynamics. They are placed within a storm sewer in an off-line configuration, and they have access holes for routine maintenance. A manhole may be placed along the trunk sewer with a diversion weir that directs low flows to the manufactured system for water treatment. Several designs have been approved by ODOT and can be found on the Qualified Products List (QPL). Each design has its own maintenance requirements. Each manufacturer has criteria and maintenance procedures to be followed. Some of the common, general procedures are outlined below. Manufactured Systems are in-line or just off-line with the existing storm sewer system. Look for one or two manholes near to each other with Vendor s name on them either just off the road or in the road. Review the design plans to identify which manhole to open to investigate the Manufactured System. Inspect and clean each system more frequently if construction activities are being performed upstream of the manufactured system.

8 Detention Basin Detention basins are dry ponds that hold water temporarily during rain events to provide water quality and quantity treatment. Detention basins are designed to slowly discharge their volume over the course of 48 hours via an outlet structure (standard construction drawing WQ-1.1). An emergency outlet weir structure is provided for storm events greater than the design event so that damage will not occur to the detention basin. Storm water is pretreated prior to being temporarily stored in the detention basin in an effort to concentrate trash and larger sediment. This area is known as the forebay, and it is located at the upstream end of the detention basin. The entire detention basin is lined with a six inch layer of Item 601 Detention Basin Aggregate along the bottom. A Detention Basin is recognized by a depressed basin area with an outlet structure with a small orifices and a larger overflow (normally a catch basin).

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10 Retention Basin A retention basin is a wet pond that has a minimum water surface elevation between storms that is defined as the permanent pool. Above the permanent pool is a detention pool that provides for temporary storage (similar to a detention pond) that is released slowly over 24 hours or more through an outlet structure (see standard construction drawing WQ-1.1). An emergency outlet weir structure is provided for storm events greater than the design event so that damage will not occur to the retention basin. Storm water is pretreated prior to being temporarily stored in the retention basin in an effort to remove trash and larger sediment. This area is known as the forebay. It is located at the upstream end of the retention basin. The entire retention basin is lined with a six inch layer of Item 601 Detention Basin Aggregate along the bottom. Retention Basins differ from detention basins as evident by standing water being present over the majority of the basin. Care should be taken to check the database or plans to ensure a detention basin isn t clogged making it appear to be a Retention Basin. There is an outlet structure with small orifices behind a screen or rock filter and a larger overflow (normally a catch basin).

11 Infiltration Trench An infiltration trench is an excavated trench that has been lined with a geotextile fabric and backfilled with aggregate (see standard construction drawing WQ-1.2). The storm water is filtered through the aggregate and is stored in the pore volume of the backfill material. It is allowed to percolate through the sides and bottom of the trench slowly over 24 hours. A layer of 6 inches of Item 601 Infiltration Basin Aggregate is provided across the top of the trench to assist in pretreatment of the surface water. In addition to the aggregate, a vegetated filter strip or vegetated swale is used for pretreatment of the surface water. Infiltration Trenches are distinguished from typical trenches as they have aggregate along the ditch line, sometimes clogged with vegetation, and an observation port and overflow catch basin structure. An inspection well is provided at the center of the trench to allow for routine viewing of the water level within the trench.

12 Bioretention Cell Bioretention Cells consist of depressed low-lying areas that treat storm water through evapotranspiration and filtering through a planting soil. The storm water is filtered as it passes through the soil. An underlying perforated storm sewer or underdrain captures the treated storm water and carries it to an outlet. Extensive vegetation assists in the filtration of the storm water prior to filtering through the soil. Vegetation should consist of shrubs or grasses that are native to the area. During construction the existing soil was removed and replaced. The bioretention planting soil (plan note W101) consists of a mixture of sand, topsoil, and compost. Therefore, the Cell is an area planted with grass or shrubs that is delineated from the surrounding area by a structure or change in vegetation ODNR s Rainwater & Land Development Manual gives the following guidance on maintaining a Bioretention Cell: Proper functioning of a bioretention practice is dependent on the planting soil continuing to drain, and the plant survival. Most maintenance activities influence these goals. Maintaining the pretreatment area and minimizing erosion will extend the life of the planting soil. Bioretention areas are a landscaped feature of a site and regular attention to the plants is necessary. Take measures to insure winter snow plowing does not pile snow on the landscaped ponding area. Over time (3-10 years), clogging of the planting soil or filter layer with fines particles may occur. This is expected and can be corrected by replacing a portion of the planting soil or replacing all the planting soil and the filter layer until better permeability is achieved. An observation port and overflow catch basin or weir will be present.

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14 Exfiltration Trenches Exfiltration Trenches do not need to be inventoried nor maintained. They are only mentioned because over 3,000 were constructed across Ohio. These devices were determined to be too labor-intensive to maintain. An Exfiltration Trench is a narrow trench filled with aggregate along the curb, sometimes clogged with vegetation. They are normally just upstream of an inlet into the storm sewer system.

15 The following have limited use in Ohio at this time. The manual will be updated to better reflect descriptions with photographs. Constructed Wetland Constructed wetlands treat storm water through bio-retention. They are depressed, heavily planted areas that are designed to maintain a dry weather flow depth ranging between 0.5 to 2 feet. Infiltration Basin An infiltration basin is an open surface pond that uses infiltration into the ground as the primary outlet structure. A bypass outlet structure and/or a weir structure may be used for storm events larger than the design storm. Infiltration basins are designed to slowly discharge their volume over the course of 24 to 48 hours (depending upon the underlying soil properties). An inspection well(s) will be provided for routine inspection of the water level. A layer of 6 inches of Item 601 Infiltration Basin Aggregate is provided across the bottom of the basin to assist in pretreatment of the surface water. In addition to the aggregate, a vegetated filter strip or vegetated biofilter is used for pretreatment of the surface water. Underground Detention Underground detention areas are made up of a series of conduits or vaults. They range from an oversized storm sewer to a series of conduits that are specifically used for storm water detention. Stream Grade Control

16 III. Initial Inventory and Inspection of Active BMP s The purpose of the initial field inventory and inspection of Active Stormwater BMP s is to verify the location of the current Stormwater BMP inventory and to perform the initial inspection. Labor, equipment, and material time shall be charged to M , Stormwater BMP Inspection. Once the location of Active BMP s is verified, no further action regarding the location is necessary, simply perform an annual inspection. Inventory and inspection of newly constructed (Proposed) BMP s is discussed in Section VI, Inventory and Inspection of Newly Constructed BMP s. The BMP database was, and will continue to be, populated by a district P & E representative with the appropriate attributes. The location of Active BMP s was developed by reviewing construction plans and approximating the location using lat/long coordinates. In most cases, the location of the BMP as identified on the Collector App will be the location in the field and no change to the location is required. If the location of an Active BMP on the Collector App cannot be found in the field, is on the wrong side of the road or fence line in the field, doesn t make sense, or is confusing to locate, please check with the hydraulic representative (see Appendix A) in your district P & E department. Rely on the hydraulic representative to help correct or tweak the location in the Collector App to match the field location. A second site visit, this time with the representative, may be required. In addition, at least one photograph is needed for each Active BMP. The photograph will aid future annual inspections by visually confirming the BMP being inspected and documenting any changes of the BMP over time. The initial field inventory can be combined with the initial inspection. Training in the use of the Collector User Guide published by the Office of Technical Services and this Manual is required. The following information is to be captured in the initial field inventory, initial inspection and all subsequent inspections according to the type of BMP. Example photographs of the Inspection Item/Maintenance Issue are depicted in Appendix B.

17 Vegetated Biofilter Confirm or correct the start location according to lat/long coordinates Confirm or correct the end location according to lat/long coordinates Take one photograph that captures: o the BMP in context with the roadway o each maintenance issue. Perform the initial inspection. Inspection Item/Maintenance Issue Check Erosion/Ruts/Gullies Remove Sediment/Trash/Debris Remove Woody Vegetation Maintain Ditch Bottom Grass Coverage 80% Maintenance Activity Level out ruts, gullies, or anything causing concentrated flow. Don t create ruts with equipment. Reseed and replace Item 670, Ditch Erosion Protection after any earthwork to achieve 80% grass coverage. Pick up any trash that accumulates and dispose according to C&MS Inspect the vegetation. Ensure the grass is well established along the bottom, foreslope, and backslope of the swale. Grass should cover at least 80% of the surface area of the vegetated biofilter in all areas. Maintain ditch bottom to original width Maintain a flat ditch bottom. Reseed and replace Item 670, Ditch Erosion Protection after any earthwork to achieve 80% grass coverage. Reseed and replace Item 670, Ditch Erosion Protection after any earthwork to achieve 80% grass coverage. Don t expose bare soil without re-establishing vegetation. The comment field should describe the maintenance issue.

18 Vegetated Filter Strip Confirm or correct the start location according to lat/long coordinates Confirm or correct the end location according to lat/long coordinates Take one photograph that captures: o the BMP in context with the roadway o each maintenance issue. Perform the initial inspection. Inspection Item/Maintenance Issue Check Erosion/Ruts/Gullies Remove Sediment/Trash/Debris Remove Woody Vegetation Grass Coverage 80% Maintenance Activity Ensure the slope is void of any ruts, gullies, or concentrated flow damage. Level out ruts, gullies, or anything causing concentrated flow. Don t create ruts with equipment. Reseed and replace Item 670, Slope Erosion Protection after any earthwork to achieve 80% grass coverage. Pick up any trash that accumulates and dispose according to C&MS Inspect the vegetation. Ensure the grass is well established along the bottom, foreslope, and backslope of the swale. Grass should cover at least 80% of the surface area of the vegetated biofilter in all areas. Ensure the grass is well established along the width of the strip. Reseed and replace Item 670, Ditch Erosion Protection after any earthwork to achieve 80% grass coverage. Don t expose bare soil without re-establishing vegetation. The comment field should describe the maintenance issue.

19 Manufactured System Confirm or correct the location according to lat/long coordinates. To correct the location, stand over the Manufactured System and tap the Use My Location button. Take one photograph that captures: o The BMP in context with the roadway. o The name of the manufacturer listed on the access cover. Perform the initial inspection. Inspection Item/Maintenance Issue Remove Sediment/Trash/Debris Maintenance Activity Remove accumulated material with a vac truck which may require jetting the sediment to loosen it before being able to vacuum it out. Inspect and clean the diversion weir structure (manhole placed along the storm sewer trunk line). When removing accumulated material, sample the removed material and test as hazardous/nonhazardous (same as done for catch basins). Do not flush the system and wash polluted material downstream. Dispose of it according to C&MS Do not perform maintenance during a rain event. The comment field should describe the maintenance issue and name of the manufacturer.

20 Detention Basin Confirm or correct the location according to lat/long coordinates Take one photograph that captures: o The BMP in context with the roadway. o A close up of the overflow catch basin and small orifice(s) Perform the initial inspection. Inspection Item/Maintenance Issue Check Erosion/Ruts/Gullies Remove Sediment/Trash/Debris Remove Woody Vegetation Check Ponding Inspect Bank & Overflow Weir Inspect Outlet Remove Sediment in Forebay & Regrade Maintenance Activity Remove litter and debris and dispose of it according to C&MS Check for excessive vegetation growing on the bottom of the basin that will diminish the capacity of the basin or clog the invert. Remove woody vegetation on embankment slopes or areas that could reduce the structural integrity of the basin Check for ponding 72 hours after a significant rain event of at least 0.5 inches falling in 24 hours. If ponding exists, verify with P&E that it should be dry and check outlet structure for clogging Inspect embankments and emergency overflow weir. Ensure they are intact and structurally sound Inspect the outlet structure. Ensure the riser pipe orifice holes are not clogged and the catch basin is free from any debris Check for erosion or sediment deposition in pretreatment areas. Clean out and repair damaged areas and dispose of it according to C&MS The comment field should describe the maintenance issue.

21 Retention Basin Confirm or correct the location according to lat/long coordinates Take one photograph that captures: o The BMP in context with the roadway. o A close up of the overflow catch basin and small orifice Perform the initial inspection. Inspection Item/Maintenance Issue Check Erosion/Ruts/Gullies Remove Sediment/Trash/Debris Remove Woody Vegetation Check Ponding Inspect Bank & Overflow Weir Inspect Outlet Maintenance Activity Check for erosion or sediment deposition in pretreatment areas. Clean out and repair damaged areas. Dispose of removed material according to C&MS Remove litter and debris and dispose of it according to C&MS Ensure basin does not fill with vegetation. Remove woody vegetation on embankment slopes or areas that could reduce the structural integrity of the basin Check for excessive ponding above the permanent volume level 72 hours after a significant rain event (0.5 inches of rain falling in 24 hours). Consult original plans for normal pond elevation and check outlet structure for proper function Inspect the outlet structure. Ensure the riser pipe orifice holes are not clogged and the catch basin is free from any debris Inspect embankments and emergency overflow weir. Ensure they are intact and structurally sound The comment field should describe the maintenance issue.

22 Infiltration Trench Confirm or correct the start location according to lat/long coordinates Take one photograph that captures each of the following conditions: o The BMP in context with the roadway. o A close up of the overflow catch basin and observation port Perform the initial inspection. Inspection Item/Maintenance Issue Check Erosion/Ruts/Gullies Remove Sediment/Trash/Debris Remove Woody Vegetation Check Observation Wells Check for Compaction Maintenance Activity Ensure pretreatment of runoff is maintained to extend the life of the Infiltration Trench. Ensure that the pretreatment vegetated strip or swale are in good condition with at least 80% grass coverage and with no ruts or gullies causing concentrated flow Remove any sediment or debris within the pretreatment strip, swale, or Infiltration Basin Aggregate. Dispose of it according to C&MS Ensure woody vegetation is not present at or immediately near the Infiltration Trench. Trim adjacent trees to assure that drip-line does not extend over the surface of the Infiltration Trench. Do not allow grass clipping or leaves to cover the trench Check observation wells 72 hours after a significant rain event. If water is found after 72 hours then the infiltration trench is considered clogged. Perform the following: Remove the Infiltration Basin Aggregate and scarify the soil by a tilling method to a depth of at least 8 inches (12 inches preferred). Regrade the trench after scarifying the soil (take care to not compact the soil). Add a new 6 layer of Item 601 Infiltration Basin Aggregate after regrading the trench Ensure basin trench is dry prior to cleaning to reduce soil compaction. Ensure the trench does not get compacted by equipment. The comment field should describe the maintenance issue.

23 Bioretention Cell Confirm or correct the location according to lat/long coordinates Take one photograph that captures: o The BMP in context with the roadway. o The location of the observation port o A close up of the overflow catch basin or weir Perform the initial inspection. Inspection Item/Maintenance Issue Check Erosion/Ruts/Gullies Remove Sediment/Trash/Debris Add Mulch Check Ponding Check for Compaction Inspect Outlet Inspect/Replace Diseased Plants Maintenance Activity Check for erosion or deposition in pretreatment areas; Clean out and repair damaged areas. Dispose of this according to C&MS Remove litter and debris. Dispose of this according to C&MS Add additional mulch if bioretention cell is planted with shrubs Check bioretention cells for excessive ponding hours following rain event of at least 0.5 inches falling in 24 hours. If excessive ponding exists, the planting soil may be clogged. If the planting soil is clogged, remove the top layer and replace with new engineered planting soil. After unclogged planting soil is replaced, vegetation must be reestablished To prevent compaction of planting soil, avoid vehicle traffic, including riding mower traffic, on bioretention cell area Inspect outlet structure. Ensure the riser pipe orifice holes are not clogged and the catch basin is free from any debris. Check original plans to determine elevation of outlet and elevation of depressed area to determine if proper ponding depth is present Inspect & replace poorly suited or diseased plants if bioretention cell is planted with shrubs

24 Mow Grass Prune/Weed/Water Plants If bioretention cell is planted with grass, mow the bioretention cell area in order to maintain healthy grass coverage. To prevent compaction of planting soil, avoid vehicle traffic, including riding mower traffic, on bioretention cell area. Grassed bioretention cells may be mowed with hand operated equipment or with an extended mower that allows tire traffic to remain outside of the cell area Water Plants. Prune and weed plants for appearance if bioretention cell is planted with shrubs The comment field should describe the maintenance issue. As previously mentioned, a photograph of the BMP serves two primary purposes. First, the photograph documents where the BMP is located thus aiding the next inspector, a year from now, to know he/she is at the proper location. The photograph should be taken of the BMP in the context of the highway system. In the photo of the BMP, try to include a sign, utility poles, driveways, or other distinguishing characteristic that is unlikely to move from year-to-year. The second purpose of the photograph is to document conditions at that time and over time. If the condition of the BMP is consistent throughout, one photograph depicted the overall condition is adequate. If several Inspection/Maintenance Issues are present, take one photo of each issue. This photo, along with a site visit, will aid the manager is assessing the condition, materials need to address the issue, crew size, equipment, etc.

25 The following Stormwater BMP s have limited use in Ohio at this time. The manual will be updated to better reflect Inspection Item/Maintenance Issues and Maintenance Activity. Constructed Wetland Infiltration Basin Underground Detention Stream Grade Control

26 IV. BMP Maintenance Labor, equipment, and material time shall be charged to M , Stormwater BMP Maintenance. V. Annual Inspections Perform the annual inspection in accordance with this manual. Labor, equipment, and material time shall be charged to M , Stormwater BMP Inspection. VI. Inventory and Inspection of Newly Constructed BMP s Newly constructed BMP s are to be inventoried and inspected prior to Maintenance accepting ownership and responsibility. While the project, and thus the BMP s, are in the design stage, the designer is to populate the BMP database with the attributes of the BMP. At this time, the Status of the BMP is Proposed. Proposed BMP s are shown in Red on the Collector App. The location of the BMP, as shown on the plans and in the database, could change during construction due to field conditions, change orders, etc. BMP s are typically shown or listed on the Project Site Plan. At the end of the project, Construction personnel and the County Manager, or designated representatives, should meet at the project site to verify the location and condition of the BMP. This meeting should take place in the same time frame as the Final Acceptance/Final Inspection. One district s best practice is for the County Manager to be invited to and attend the Final Inspection. This meeting will constitute the transfer of the BMP from Construction to Maintenance except as discussed below. At this point in time, the status of the BMP is switched from Proposed to Active in the Collector App. Any corrections in the location should be made to the inventory. A picture of the BMP, as part of the inventory record, should be taken. The first inspection should also take place. If the BMP is not functioning according to these Inventory, Inspection and Maintenance Guidelines or any inspection item is marked Maintenance Required, the County Manager should request the BMP(s) be added to the Punch List. For example, a Vegetated Biofilter and Vegetated Filter Strip should have well established grass covering over 80% of the surface area. The slopes should be void of woody vegetation, gullies, ruts, or trash. Bioretention Cells should have adequate mulch, healthy, growing shrubs or grass, and the outlet structure free from debris. Manufactured Systems should be fully cleaned of sediment from construction runoff. A follow up inspection for BMP s on the Punch List will then constitute the transfer.

27 VII. Appendix A (District Representatives) District Hydraulic Representatives (August, 2017) District Hydraulic Representative 1 Ian Kohli 2 Jorey Summersett 3 Dustin Vousden, Adam Mellen 4 Bob Rosen 5 Heather Gilbert 6 Jon Adams 7 Matt Blythe 8 Tami Brehm 9 Matt Hauck 10 Scott Latture 11 Jason Beranek 12 Michael Moriarty District TAM Coordinators (August, 2017) District MS4 Liaisons (August, 2017) District TAM Coordinator 1 Cody Lape 2 Ben Cordes 3 Jonathan Keller, Phillip Gabel 4 Tom Buckler 5 Gary VanHove 6 Nick Villaveces 7 Amy Code 8 Amy Code, Keith Smith 9 Eric Beery 10 Joshua Booher 11 Scott Warner 12 Valerie Swancer District MS4 Liaison 1 Brett Allerding 2 Jorey Summersett 3 Don Rostofer 4 Jim McGrath 5 Steve Smith 6 Jon Adams 7 Ramona Diehl 8 Sam Bynum 9 Greg Manson

28 10 Greg Huffman 11 Anna Kuzmich 12 Lou Mincek

29 VIII. Appendix B (Inspection Item/Maintenance Issue) Check Erosion/Ruts/Gullies Examples of erosion/ruts/gullies where maintenance is required. Remove Sediment/Trash/Debris Examples of Sediment/Trash/Debris where maintenance is required. Remove Woody Vegetation Example of Woody Vegetation where maintenance is required. Maintain Ditch Bottom Examples of Ditch Bottom where maintenance is required.

30 Grass Coverage 80% Examples of 80% to 100% Grass Coverage where maintenance is not required. Examples of less than 80% Grass Coverage where maintenance is required. Check Ponding Inspect Bank & Overflow Weir Inspect Outlet Check Observation Wells Clogged Outlet Leads to Ponding

31 Unclogging Outlet Leads to Flowing Water Check for Compaction Add Mulch Check Ponding Inspect/Replace Diseased Plants Mow Grass Prune/Weed/Water Plants Remove Sediment/Trash/Debris from Manufactured Systems

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