Building Review



Public Works Storm Water
Review No:1 Application with Stormwater Report dated 9/16/22 and civil plans dated 9/8/22 by Sherwood Design Engineers has been received. Please address the following: 1. Final Stormwater Management Plan (SWP) and Final Civil Plans: A final stormwater management plan and civil plans consistent with the requirements in Appendix D for large building permit applications are required prior to building permit issuance and shall address the following: a. Show all existing drainage infrastructure on the site and nearby areas. The preliminary site plans show several storm drain inlets but do not show the storm drain facilities from these inlets. Provide a full description and evaluation of the adequacy of any/all storm drain facilities that are to remain on the site and where/how they discharge – this shall include analysis of the current condition of facilities based on video inspection. If drainage facilities are located near or below structures they should be moved. b. Final details, materials, specifications and methods of construction and methods for permeability/infiltration testing and acceptable thresholds for facilities that rely on infiltration. The test specified on detail 2/C5.02 requires additional borings and profiles. Consider specifying a test that can be used to verify the surface infiltration rate at the basin surface without additional disturbance (single or double ring infiltrometer test, constant head permeameter, etc.). c. Approval from the project geotechnical engineer for the final plans prior to building permit issuance is required. d. Include storm drain markings “No Dumping Drains to Bay” at each inlet in the project limits. These markings shall be maintained by the property owner and identified in the maintenance agreement. e. Demonstrate that there is adequate separation between drainage facilities and septic facilities and drainage facilities and expected groundwater. 2. Final Stormwater Management Report: Provide a final signed and stamped report with analysis supporting the final stormwater management plan and demonstrating the design is in compliance with Part 3 of the CDC and that includes the following: a. The water quality and flood control evaluation was based on a design infiltration rate of 2 inches/hour which is not a conservative based on the soil types in the vicinity of the basins. Both Basin A and B are mapped as Danville loam which has an infiltration rate of 0.06-0.2 inches/hour, which is significantly less than the design rate used. As described in the CDC saturated soil permeability and hydraulic conductivity values may be used conservatively (which equates to 0.06 inches/hour for this soil) from the published physical properties table within the USDA NRCS soil survey, or use actual test values. If actual test values will be used, provide test configuration results and analysis to account for surface area to volume ratio used (diameter of test holes, backfilling, etc.) and calculate an adjusted design infiltration rate. Percolation test results cannot be used directly as a design infiltration rate without making these adjustments. Please update analysis to be consistent with CDC guidelines. If infiltration is not feasible, it appears that the basins proposed may be updated to be consistent with the biofiltration cross section requirements for compliance with CDC requirements for minimizing stormwater pollutants of concern. b. It may also be possible to use the basins for complying with the maintenance of stormwater discharge rates and volumes. Based on grades if design is updated to provide controlled release structures set 6 inches above the pond surface with required detention volumes between the controlled release elevation and pond overflow elevation the water quality and flood control mitigations may stay combined and be consistent with CDC requirements. Please note that the required detention volumes for each subwatershed shall be determined based the comparison of the post development 10 year flows and the predevelopment 10 year 15 minute flow rate for a range of storm durations (please see Figures SWM-16 and 17 for minimum requirements). If the design infiltration rate is determined to be high (similar to the 2 inch/hour used) and retention and infiltration will be used to mitigate for the 10 year storm, then the required 10 year detention volume may be determined by following the example in Figure SWM-16 but using the expected infiltration rate in each basin (based on effective surface area and design infiltration rate) set at Qpre. c. A site assessment performed by the project Engineer that evaluates whether there are any existing stormwater (drainage) issues on or near the site and if any stormwater (drainage) issues or impacts are anticipated resulting from the proposed improvements. See comment 1.a above. 5. Recorded maintenance agreement(s) for stormwater management and mitigation facilities is required. Include attachments showing: watershed map with locations of all stormwater facilities, detailed management activities, maintenance requirements, schedule, signs of system failure, and responsible party for all facilities on the project site. The checklist for the any biofiltration facilities and pervious or semi-impervious hardscapes shall include at least annual surface infiltration testing and thresholds for maintenance and/or replacement for the facilities as well as at least annual check for minimum surface area and ponding depth for each. Include a checklist for the maintenance of the detention system and associated orifices and structures, offsite bypass systems, outfalls, “No dumping” markings in the SWM25B. Include a statement that no additional impervious or semi-impervious areas will be added on the project site without additional permits and mitigations. 6) Since the parcel/s being developed receives existing runoff from an adjacent drainage areas, the recordation of a drainage easement, maintenance agreement, deed restriction, or other document recorded on the parcel deed/s will be required. The recorded document shall acknowledge that the parcel does and will continue to receive upstream runoff, that the property owner is responsible for maintenance of the drainage pathway (natural and/or man-made) through the parcel, and that the County and Flood Control District(s) are not responsible for the upstream runoff or for maintenance of the drainage pathway. This may be combined in the SWM-25B. 8) Zone 8 impervious area impact fees will be assessed based on the net increase in permitted impervious areas. For credit for existing areas to be replaced please provide documentation demonstrating these areas were built with a permit or prior to 1977. The current fee schedule is $1.49 per square foot of new impervious area and is subject to change each year. 9) Public Works staff will inspect the construction of the drainage related items. Please provide engineer’s estimate for the construction of the drainage items (there is a 3 % inspection fee). A hold will be placed on the building permit for a preconstruction meeting with the Public Works Construction Engineer (please email at least 48 hours prior to construction to schedule the preconstruction meeting at: DPWCMInspection@santacruzcounty.us). A second hold will be made for approval of the final construction by the Public Works Construction Inspector. 10) Add the following note to final Civil Plans: As-built digital file for all drainage facilities shall be submitted prior to permit final and occupancy. The submittal shall contain the following criteria: Projection: State Plane Coordinate System - California III - Feet Horizontal Datum: NAD 83 Vertical Datum: NAVD 88 Any CAD is acceptable. AutoCAD is preferred. The file can be emailed to the GIS staff or be submitted on a compact disc once it is approved by the construction inspection staff. A hold on the building permit will be placed for submittal and approval of the as built plans. Review No:2 Application with Stormwater Management Report dated 1/13/23 and civil plans dated 1/24/23 by Sherwood Design Engineers has been received. Please address the following: 1. Final Stormwater Management Plan (SWP) and Final Civil Plans: A final stormwater management plan and civil plans consistent with the requirements in Appendix D for large building permit applications are required prior to building permit issuance and shall address the following: a. The updated plans show the location of the existing piped channel through the property. The plans and report describe an 18 inch concrete culvert that undergrounds an ephemeral drainage channel running underneath the existing home to be remodeled with this project. This pipe should be moved from under the residential structure. Section 7.0 of the Stormwater Management Report includes a narrative summary of the condition analysis of the 18 inch concrete culvert and identifies a section in need of repair. Attachment 5 of the Stormwater Management Report is labelled Culvert Condition Analysis, but the analysis was not included in the materials submitted via bluebeam. Please provide the analysis of the current condition of facilities based on video inspection. b. If the pipe location under the residence is pursued provide details for the proposed repair/replacement in the project plans. An easement or other document will be needed to allow for this continued routing. This legally binding document shall be recorded on the property and shall acknowledge that the property owner is responsible for maintenance of the drainage pathway (piped channel) that runs through the property and under residential structures, and that the County and Flood Control District(s) are not responsible for the upstream runoff or for maintenance of the drainage pathway. c. Demonstrate that there is adequate separation between drainage facilities and septic facilities. Retention facilities shall be located a minimum of 25 feet from any septic leach field – does Basin C meet this setback? 2. Final Stormwater Management Report: Provide a final signed and stamped report with analysis supporting the final stormwater management plan and demonstrating the design is in compliance with Part 3 of the CDC. a. The report includes references and description of using the porchet method for determining a measured infiltration rate from a measured percolation rate. Both references also include required safety factors be applied to the measured infiltration rate before determining the design infiltration rate to be used for BMP sizing. Please provide a design infiltration rate that includes an appropriate safety factor. b. Provide a sample calculation demonstrating how the design release rate was calculated for use in SWM-16 to determine the required 10 year retention volume. Has the conversion from inches to feet been taken into account? c. If analysis shows the 10 year storm volume can be stored and infiltrated in the ponds, evaluation of the 2 year storm is not also required. 3. The updated plans include work within Caltrans property. Please provide written approval from Caltrans for the proposed plan including the proposed outlets, valley gutters, etc. to be constructed on Caltrans property. 4. Provide an updated SWM-25B (since the project is large) maintenance agreement. Section 1.1 shall be updated to say additional impervious or semi-impervious areas cannot be added on the project site without additional permits and mitigations. Update the agreement to include inspections and maintenance of the proposed outfall facilities at the Caltrans right of way, or provide written documentation from Caltrans that they will maintain these. Update facilities map to include surface area and depth of each infiltration basin and include inspection and maintenance procedures to ensure that the basin volumes are maintained as designed. Specify what is meant by annual observation of the 18 RCP pipe. 5. Provide written approval from the project geotechnical engineer for the final plans prior to building permit issuance is required. 6. Zone 8 impervious area impact fees will be assessed based on the net increase in permitted impervious areas. For credit for existing areas to be replaced please provide documentation demonstrating these areas were built with a permit or prior to 1977. The current fee schedule is $1.49 per square foot of new impervious area and is subject to change each year. 7. Public Works staff will inspect the construction of the drainage related items. Thank you for the engineer’s estimate for the construction of the drainage items. The inspection fee will be assessed when the building permit is issues. A hold will be placed on the building permit for a preconstruction meeting with the Public Works Construction Engineer (please email at least 48 hours prior to construction to schedule the preconstruction meeting at: DPWCMInspection@santacruzcounty.us). A second hold will be made for approval of the final construction by the Public Works Construction Inspector. Review No:3 Application with Stormwater Management Report dated 6/22/23 and civil plans dated 6/27/23 by Sherwood Design Engineers has been received. Please address the following: 1. Final Stormwater Management Plan (SWP) and Final Civil Plans: A final stormwater management plan and civil plans consistent with the requirements in Appendix D for large building permit applications are required prior to building permit issuance and shall address the following: a) Plans now show a second pipe running under the main residence. Update the plans to include video inspection of the 4” storm drain pipe under the ADU/main house prior to occupancy/building permit final. If the pipe is in poor condition then it shall be moved from under the building. There will be a hold placed on the building permit for these inspection and relocation/repair results. b) Call out 1.1 for stormwater basin labelled on the geogrid roadway section on sheets 4.02 and 4.04 should be removed and replaced with reference to detail 5/C5.02. c) The proposed orifice sizes for basins D and E are not feasible for construction or for maintenance. Please eliminate these facilities and route an equivalent impervious area to basins A, B and/or C and update their sizing accordingly. d) Will impermeable liners running vertically between the geogrid permeable pavement areas and the septic leachfield areas be provided consistent with the requirements emailed in May 2023? Detail 5/C5.02 does not show this liner. Why are there two different cross sections shown in this detail? Which cross section is proposed where? e) The trash storage area shall incorporate source control measure stormwater BMPs to prevent trash or other pollutants from entering the stormwater system (see Part 3 Section E of the CDC and CASQA BMP SD-32). Runoff from the trash enclosure area shall not be routed to infiltration facilities, the area shall be covered or bermed and BMPs for maintenance shall be included the SWM-25B. f) Provide a detail/s for the proposed rock dissipators and storm drain outfalls in Caltrans right of way. Provide written approval from Caltrans for the proposed stormwater proposal including the outfalls in Caltrans right of way and work around the existing inlet. Inspection for the construction of the outfalls and other improvements within Caltrans right-of-way shall be conducted by Caltrans. 2. Provide an updated SWM-25B that is signed and recorded prior building permit finals and occupancy. The updated agreement shall address: a) The report and agreement not state that the property owner will take on responsibility for the 30 inch storm drain pipe downstream of the site in Caltrans right of way. A separate agreement is required with Caltrans for this maintenance. The SWM-25B can reference the agreement with Caltrans, but the County of Santa Cruz cannot be responsible for the O&M oversight for the facility on Caltrans property. b) The agreement shall be updated to include regular video inspection of the 4 inch pipe running underneath the main building ADU similar to the 18 inch pipe. c) Update so that in the case that either the 18 inch or 4 inch storm drain pipe running under the residential structure requires replacement the pipes shall be relocated from under the structure. 3. Zone 8 impervious area impact fees will be assessed based on the net increase in permitted impervious areas. For credit for existing areas to be replaced please provide documentation demonstrating these areas were built with a permit or prior to 1977. 4. Public Works staff will inspect the construction of the drainage related items. Thank you for the engineer’s estimate for the construction of the drainage items. The inspection fee will be assessed when the building permit is issued. A hold will be placed on the building permit for a preconstruction meeting with the Public Works Construction Engineer (please email at least 48 hours prior to construction to schedule the preconstruction meeting at: DPWCMInspection@santacruzcounty.us). A second hold will be made for approval of the final construction by the Public Works Construction Inspector. Review No:4 Application with Stormwater Management Report dated 12/20/23 and civil plans dated 11/15/23 by Sherwood Design Engineers has been received. Please address the following: 1. Final Stormwater Management Plan (SWP) and Final Civil Plans: A final stormwater management plan and civil plans consistent with the requirements in Appendix D for large building permit applications are required prior to building permit issuance and shall address the following: a) Updated plans show rerouting the existing 4 inch storm drain line from under the existing structure. Please include detail/s for access openings for this pipe and all other proposed pipes included in this project for access at all horizontal angle points and changes in grade, or pipe size, and pipe connections (CDC Part 3 Section K.2.c). b) The stormwater feature schedule on sheet C4.00 and details 2 and 5 of C5.02 are insufficient for construction and inspection and are inconsistent with the analysis. Update inconsistencies in the rim elevations for basin C and provide top and bottom of basin elevations on the grading plan. Please update details 7/C5.02 to include invert elevations for the orifices, weir notch, top of grate, and top or bottom of basin. The plans shall also include dimensions (at top and bottom of basins) that correspond with the minimum surface area and volumes from the analysis. This will aide in construction, inspection, and annual maintenance and monitoring. The basins shall be hydraulically connected to the flow control structures (provide openings in the side of the control boxes, or some other mechanism/s) at all elevations above the orifice/bottom of detention volume so that constant release is provided consistent with the detention storage analysis. 2. Zone 8 impervious area impact fees will be assessed based on the net increase in permitted impervious areas. For credit for existing areas to be replaced please provide documentation demonstrating these areas were built with a permit or prior to 1977. These fees will be assessed with building permit issuance and will be based on 5,168 sf of net new impervious area. 3. Public Works staff will inspect the construction of the drainage related items. Thank you for the engineer’s estimate for the construction of the drainage items. The inspection fee will be assessed when the building permit is issued. A hold will be placed on the building permit for a preconstruction meeting with the Public Works Construction Engineer (please email at least 48 hours prior to construction to schedule the preconstruction meeting at: DPWCMInspection@santacruzcounty.us). A second hold will be made for approval of the final construction by the Public Works Construction Inspector.

Public Works Storm Water

Review No:1

Application with Stormwater Report dated 9/16/22 and civil plans dated 9/8/22 by Sherwood Design Engineers has been received. Please address the following:

1. Final Stormwater Management Plan (SWP) and Final Civil Plans:

A final stormwater management plan and civil plans consistent with the requirements in Appendix D for large building permit applications are required prior to building permit issuance and shall address the following:

a. Show all existing drainage infrastructure on the site and nearby areas. The preliminary site plans show several storm drain inlets but do not show the storm drain facilities from these inlets. Provide a full description and evaluation of the adequacy of any/all storm drain facilities that are to remain on the site and where/how they discharge – this shall include analysis of the current condition of facilities based on video inspection. If drainage facilities are located near or below structures they should be moved.

b. Final details, materials, specifications and methods of construction and methods for permeability/infiltration testing and acceptable thresholds for facilities that rely on infiltration. The test specified on detail 2/C5.02 requires additional borings and profiles. Consider specifying a test that can be used to verify the surface infiltration rate at the basin surface without additional disturbance (single or double ring infiltrometer test, constant head permeameter, etc.).

c. Approval from the project geotechnical engineer for the final plans prior to building permit issuance is required.

d. Include storm drain markings “No Dumping Drains to Bay” at each inlet in the project limits. These markings shall be maintained by the property owner and identified in the maintenance agreement.

e. Demonstrate that there is adequate separation between drainage facilities and septic facilities and drainage facilities and expected groundwater.

2. Final Stormwater Management Report:

Provide a final signed and stamped report with analysis supporting the final stormwater management plan and demonstrating the design is in compliance with Part 3 of the CDC and that includes the following:

a. The water quality and flood control evaluation was based on a design infiltration rate of 2 inches/hour which is not a conservative based on the soil types in the vicinity of the basins. Both Basin A and B are mapped as Danville loam which has an infiltration rate of 0.06-0.2 inches/hour, which is significantly less than the design rate used. As described in the CDC saturated soil permeability and hydraulic conductivity values may be used conservatively (which equates to 0.06 inches/hour for this soil) from the published physical properties table within the USDA NRCS soil survey, or use actual test values. If actual test values will be used, provide test configuration results and analysis to account for surface area to volume ratio used (diameter of test holes, backfilling, etc.) and calculate an adjusted design infiltration rate. Percolation test results cannot be used directly as a design infiltration rate without making these adjustments. Please update analysis to be consistent with CDC guidelines. If infiltration is not feasible, it appears that the basins proposed may be updated to be consistent with the biofiltration cross section requirements for compliance with CDC requirements for minimizing stormwater pollutants of concern.

b. It may also be possible to use the basins for complying with the maintenance of stormwater discharge rates and volumes. Based on grades if design is updated to provide controlled release structures set 6 inches above the pond surface with required detention volumes between the controlled release elevation and pond overflow elevation the water quality and flood control mitigations may stay combined and be consistent with CDC requirements. Please note that the required detention volumes for each subwatershed shall be determined based the comparison of the post development 10 year flows and the predevelopment 10 year 15 minute flow rate for a range of storm durations (please see Figures SWM-16 and 17 for minimum requirements). If the design infiltration rate is determined to be high (similar to the 2 inch/hour used) and retention and infiltration will be used to mitigate for the 10 year storm, then the required 10 year detention volume may be determined by following the example in Figure SWM-16 but using the expected infiltration rate in each basin (based on effective surface area and design infiltration rate) set at Qpre.

c. A site assessment performed by the project Engineer that evaluates whether there are any existing stormwater (drainage) issues on or near the site and if any stormwater (drainage) issues or impacts are anticipated resulting from the proposed improvements. See comment 1.a above.

5. Recorded maintenance agreement(s) for stormwater management and mitigation facilities is required. Include attachments showing: watershed map with locations of all stormwater facilities, detailed management activities, maintenance requirements, schedule, signs of system failure, and responsible party for all facilities on the project site. The checklist for the any biofiltration facilities and pervious or semi-impervious hardscapes shall include at least annual surface infiltration testing and thresholds for maintenance and/or replacement for the facilities as well as at least annual check for minimum surface area and ponding depth for each. Include a checklist for the maintenance of the detention system and associated orifices and structures, offsite bypass systems, outfalls, “No dumping” markings in the SWM25B. Include a statement that no additional impervious or semi-impervious areas will be added on the project site without additional permits and mitigations.

6) Since the parcel/s being developed receives existing runoff from an adjacent drainage areas, the recordation of a drainage easement, maintenance agreement, deed restriction, or other document recorded on the parcel deed/s will be required. The recorded document shall acknowledge that the parcel does and will continue to receive upstream runoff, that the property owner is responsible for maintenance of the drainage pathway (natural and/or man-made) through the parcel, and that the County and Flood Control District(s) are not responsible for the upstream runoff or for maintenance of the drainage pathway. This may be combined in the SWM-25B.

8) Zone 8 impervious area impact fees will be assessed based on the net increase in permitted impervious areas. For credit for existing areas to be replaced please provide documentation demonstrating these areas were built with a permit or prior to 1977. The current fee schedule is $1.49 per square foot of new impervious area and is subject to change each year.

9) Public Works staff will inspect the construction of the drainage related items. Please provide engineer’s estimate for the construction of the drainage items (there is a 3 % inspection fee). A hold will be placed on the building permit for a preconstruction meeting with the Public Works Construction Engineer (please email at least 48 hours prior to construction to schedule the preconstruction meeting at: DPWCMInspection@santacruzcounty.us). A second hold will be made for approval of the final construction by the Public Works Construction Inspector.

10) Add the following note to final Civil Plans: As-built digital file for all drainage facilities shall be submitted prior to permit final and occupancy. The submittal shall contain the following criteria: Projection: State Plane Coordinate System - California III - Feet Horizontal Datum: NAD 83 Vertical Datum: NAVD 88 Any CAD is acceptable. AutoCAD is preferred. The file can be emailed to the GIS staff or be submitted on a compact disc once it is approved by the construction inspection staff. A hold on the building permit will be placed for submittal and approval of the as built plans.

Review No:2

Application with Stormwater Management Report dated 1/13/23 and civil plans dated 1/24/23 by Sherwood Design Engineers has been received. Please address the following:

1. Final Stormwater Management Plan (SWP) and Final Civil Plans:

a. The updated plans show the location of the existing piped channel through the property. The plans and report describe an 18 inch concrete culvert that undergrounds an ephemeral drainage channel running underneath the existing home to be remodeled with this project. This pipe should be moved from under the residential structure. Section 7.0 of the Stormwater Management Report includes a narrative summary of the condition analysis of the 18 inch concrete culvert and identifies a section in need of repair. Attachment 5 of the Stormwater Management Report is labelled Culvert Condition Analysis, but the analysis was not included in the materials submitted via bluebeam. Please provide the analysis of the current condition of facilities based on video inspection.

b. If the pipe location under the residence is pursued provide details for the proposed repair/replacement in the project plans. An easement or other document will be needed to allow for this continued routing. This legally binding document shall be recorded on the property and shall acknowledge that the property owner is responsible for maintenance of the drainage pathway (piped channel) that runs through the property and under residential structures, and that the County and Flood Control District(s) are not responsible for the upstream runoff or for maintenance of the drainage pathway.

c. Demonstrate that there is adequate separation between drainage facilities and septic facilities. Retention facilities shall be located a minimum of 25 feet from any septic leach field – does Basin C meet this setback?

2. Final Stormwater Management Report:

Provide a final signed and stamped report with analysis supporting the final stormwater management plan and demonstrating the design is in compliance with Part 3 of the CDC.

a. The report includes references and description of using the porchet method for determining a measured infiltration rate from a measured percolation rate. Both references also include required safety factors be applied to the measured infiltration rate before determining the design infiltration rate to be used for BMP sizing. Please provide a design infiltration rate that includes an appropriate safety factor.

b. Provide a sample calculation demonstrating how the design release rate was calculated for use in SWM-16 to determine the required 10 year retention volume. Has the conversion from inches to feet been taken into account?

c. If analysis shows the 10 year storm volume can be stored and infiltrated in the ponds, evaluation of the 2 year storm is not also required.

3. The updated plans include work within Caltrans property. Please provide written approval from Caltrans for the proposed plan including the proposed outlets, valley gutters, etc. to be constructed on Caltrans property.

4. Provide an updated SWM-25B (since the project is large) maintenance agreement. Section 1.1 shall be updated to say additional impervious or semi-impervious areas cannot be added on the project site without additional permits and mitigations. Update the agreement to include inspections and maintenance of the proposed outfall facilities at the Caltrans right of way, or provide written documentation from Caltrans that they will maintain these. Update facilities map to include surface area and depth of each infiltration basin and include inspection and maintenance procedures to ensure that the basin volumes are maintained as designed. Specify what is meant by annual observation of the 18 RCP pipe.

5. Provide written approval from the project geotechnical engineer for the final plans prior to building permit issuance is required.

6. Zone 8 impervious area impact fees will be assessed based on the net increase in permitted impervious areas. For credit for existing areas to be replaced please provide documentation demonstrating these areas were built with a permit or prior to 1977. The current fee schedule is $1.49 per square foot of new impervious area and is subject to change each year.

7. Public Works staff will inspect the construction of the drainage related items. Thank you for the engineer’s estimate for the construction of the drainage items. The inspection fee will be assessed when the building permit is issues. A hold will be placed on the building permit for a preconstruction meeting with the Public Works Construction Engineer (please email at least 48 hours prior to construction to schedule the preconstruction meeting at: DPWCMInspection@santacruzcounty.us). A second hold will be made for approval of the final construction by the Public Works Construction Inspector.

Review No:3

Application with Stormwater Management Report dated 6/22/23 and civil plans dated 6/27/23 by Sherwood Design Engineers has been received. Please address the following:

1. Final Stormwater Management Plan (SWP) and Final Civil Plans:

a) Plans now show a second pipe running under the main residence. Update the plans to include video inspection of the 4” storm drain pipe under the ADU/main house prior to occupancy/building permit final. If the pipe is in poor condition then it shall be moved from under the building. There will be a hold placed on the building permit for these inspection and relocation/repair results.

b) Call out 1.1 for stormwater basin labelled on the geogrid roadway section on sheets 4.02 and 4.04 should be removed and replaced with reference to detail 5/C5.02.

c) The proposed orifice sizes for basins D and E are not feasible for construction or for maintenance. Please eliminate these facilities and route an equivalent impervious area to basins A, B and/or C and update their sizing accordingly.

d) Will impermeable liners running vertically between the geogrid permeable pavement areas and the septic leachfield areas be provided consistent with the requirements emailed in May 2023? Detail 5/C5.02 does not show this liner. Why are there two different cross sections shown in this detail? Which cross section is proposed where?

e) The trash storage area shall incorporate source control measure stormwater BMPs to prevent trash or other pollutants from entering the stormwater system (see Part 3 Section E of the CDC and CASQA BMP SD-32). Runoff from the trash enclosure area shall not be routed to infiltration facilities, the area shall be covered or bermed and BMPs for maintenance shall be included the SWM-25B.

f) Provide a detail/s for the proposed rock dissipators and storm drain outfalls in Caltrans right of way. Provide written approval from Caltrans for the proposed stormwater proposal including the outfalls in Caltrans right of way and work around the existing inlet. Inspection for the construction of the outfalls and other improvements within Caltrans right-of-way shall be conducted by Caltrans.

2. Provide an updated SWM-25B that is signed and recorded prior building permit finals and occupancy. The updated agreement shall address:

a) The report and agreement not state that the property owner will take on responsibility for the 30 inch storm drain pipe downstream of the site in Caltrans right of way. A separate agreement is required with Caltrans for this maintenance. The SWM-25B can reference the agreement with Caltrans, but the County of Santa Cruz cannot be responsible for the O&M oversight for the facility on Caltrans property.

b) The agreement shall be updated to include regular video inspection of the 4 inch pipe running underneath the main building ADU similar to the 18 inch pipe.

c) Update so that in the case that either the 18 inch or 4 inch storm drain pipe running under the residential structure requires replacement the pipes shall be relocated from under the structure.

3. Zone 8 impervious area impact fees will be assessed based on the net increase in permitted impervious areas. For credit for existing areas to be replaced please provide documentation demonstrating these areas were built with a permit or prior to 1977.

4. Public Works staff will inspect the construction of the drainage related items. Thank you for the engineer’s estimate for the construction of the drainage items. The inspection fee will be assessed when the building permit is issued. A hold will be placed on the building permit for a preconstruction meeting with the Public Works Construction Engineer (please email at least 48 hours prior to construction to schedule the preconstruction meeting at: DPWCMInspection@santacruzcounty.us). A second hold will be made for approval of the final construction by the Public Works Construction Inspector.

Review No:4

Application with Stormwater Management Report dated 12/20/23 and civil plans dated 11/15/23 by Sherwood Design Engineers has been received. Please address the following:

1. Final Stormwater Management Plan (SWP) and Final Civil Plans:

a) Updated plans show rerouting the existing 4 inch storm drain line from under the existing structure. Please include detail/s for access openings for this pipe and all other proposed pipes included in this project for access at all horizontal angle points and changes in grade, or pipe size, and pipe connections (CDC Part 3 Section K.2.c).

b) The stormwater feature schedule on sheet C4.00 and details 2 and 5 of C5.02 are insufficient for construction and inspection and are inconsistent with the analysis. Update inconsistencies in the rim elevations for basin C and provide top and bottom of basin elevations on the grading plan. Please update details 7/C5.02 to include invert elevations for the orifices, weir notch, top of grate, and top or bottom of basin. The plans shall also include dimensions (at top and bottom of basins) that correspond with the minimum surface area and volumes from the analysis. This will aide in construction, inspection, and annual maintenance and monitoring. The basins shall be hydraulically connected to the flow control structures (provide openings in the side of the control boxes, or some other mechanism/s) at all elevations above the orifice/bottom of detention volume so that constant release is provided consistent with the detention storage analysis.

2. Zone 8 impervious area impact fees will be assessed based on the net increase in permitted impervious areas. For credit for existing areas to be replaced please provide documentation demonstrating these areas were built with a permit or prior to 1977. These fees will be assessed with building permit issuance and will be based on 5,168 sf of net new impervious area.

3. Public Works staff will inspect the construction of the drainage related items. Thank you for the engineer’s estimate for the construction of the drainage items. The inspection fee will be assessed when the building permit is issued. A hold will be placed on the building permit for a preconstruction meeting with the Public Works Construction Engineer (please email at least 48 hours prior to construction to schedule the preconstruction meeting at: DPWCMInspection@santacruzcounty.us). A second hold will be made for approval of the final construction by the Public Works Construction Inspector.

CDI - Application Status