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20190913_Response letter 6-26-19.pdf PO Box 1478 ⬧ Everett, WA 98206 ⬧ Phone: (425) 303-9363 Fax: (425) 303-9362 ⬧ Email:info@insightengineering.net September 13, 2019 Karen Lien, Environmental Programs Manager 121 5th Avenue North Edmonds, WA 98020 (425) 771-0220 Re: Langford – PLN20180064 IECO No. 19-0992 Dear Kernen, The project referenced above is revised in response to the review comments dated June 20, 2019. The review comments are numbered on the letter and have been addressed in italics as follows: 1. Geotechnical Report: Partially addressed. The critical area determination conducted on 1136 Vista Place under file number CRA20180201 identified slopes on the site that exceed 40% which are considered potential landslide hazard areas pursuant to Chapter 23.80 ECDC. A geotechnical report consistent with the requirements of ECDC 23.80.050 and addressing the specific requirements of ECDC 23.80.060 and .070 must be prepared to evaluate the potential impacts of the proposed subdivision. Please also see the comments under Subdivision Review Criteria below which will relate to the development and review of the geotechnical report. June 20, 2019 Comment: A geotechnical report was included with the June 4 resubmittal; however, the geotechnical report did not address the criteria in ECDC 23.80.070.A.4. In particular, criterion ECDC 23.80.070.A.4.a, “The proposed development shall not decrease the factor of safety for landslide occurrences below the limits of 1.5 for static conditions and 1.2 for dynamic conditions,” is an important consideration for subdivision criterion in ECDC 20.75.080.A.4. It must be demonstrated that the site can be safely developed without impacting slope stability beyond the limits noted in ECDC 23.80.070.A.4.a. The geotechnical report notes that proposed residence should have a minimum effective setback of 10 feet from the slope face measured horizontally from the western most foot to the adjacent slope. With the proposed future residence being located on the slope, it does not appear that this setback is being met. PO Box 1478 ⬧ Everett, WA 98206 ⬧ Phone: (425) 303-9363 Fax: (425) 303-9362 ⬧ Email:info@insightengineering.net Please see attached Geotech letter. While the ten feet is recommended, it is not specifically required from a geotechnical standpoint. The Geotech even says that “the proposed residence will not increase the threat of geological hazards on adjacent properties, will not impact other critical areas, and are safe as designed under anticipated conditions.” 2. Wetland Determination: Addressed. 3. Easements: Partially addressed. The title report identifies a number of access and utility easements on the subject property. Please provide these easements which are identified by the following auditor file numbers (AFN) in the title report: 815306, 1126222, 1625989, and 1444635. Additionally, the location of these easements and any other easements on the subject property must be identified on the preliminary short plat. June 20, 2019 Comment: The revised short plat documents labels easements with the auditor file numbers, but none of the easements have been provided as requested so easement locations cannot be verified. An adjacent property owner submitted comments during the comment period and provided a copy of the easement recorded under 144635. This easement’s legal description does not line up with the location of the easement displayed on the short plat documents. Please provide copies of all the easements referenced above as well as any additional easements that may exist and ensure they are accurately displayed on the short plat documents. The easements have been provided to the extent possible. 4. Preliminary Short Plat: a. Surveyor signature – Addressed. b. Gross and Net Lot Area – Addressed. Adjust, if necessary, with future resubmittal. Identify the gross and net lot area of each of the proposed lots. Note that any access easement must be subtracted from the gross lot area and the resulting net lot area must be at 12,000 square feet. c. Please identify all structures within 25 feet of the subject property as required by ECDC 20.75.060.M. Addressed. 5. Site Bench Mark: Addressed. 6. Subdivision Review Criteria: Not Addressed. The criteria for reviewing subdivisions is contained in ECDC 20.75.085. On initial review, more documentation is needed to demonstrate that the criteria below can be met. a. ECDC 20.75.080.A.4 Where conditions exist which could be hazardous to the future residents of the land to be divided, or to nearby residents or property, such as floodplains, steep slopes or unstable soil or geologic conditions, a subdivision of the hazardous land shall be denied unless the condition can be permanently corrected, consistent with subsections (A)(1) and (2) of this section. PO Box 1478 ⬧ Everett, WA 98206 ⬧ Phone: (425) 303-9363 Fax: (425) 303-9362 ⬧ Email:info@insightengineering.net Almost all of the proposed Lot 1 consists of slopes in excess of 50%. Developing this site may require a significant cut into the hillside which could impact slope stability and existing residence on the top of the slope. The geotechnical report must address how this site could be developed and how the hazard can be permanently corrected. As noted in the Building Division comments (attached), it is likely that peer review will be required for the geotechnical analysis and design. Note the cost peer review is required to be covered by the applicant. June 20, 2019 Comment: The geotechnical report did not address this criterion. As noted above the geotechnical report did not address ECDC 23.80.070.A.4.a which is important in determining if this criterion is met. Furthermore, the geotechnical report noted the proposed residence should have a minimum effective setback of 10 feet from the slope face measures horizontally from the western most foot to the adjacent slope, which would prevent a house from being constructed on the slope. Please see the attached Geotech letter. This should now be addressed. For the slope setback, please see the previous response. b. ECDC 20.75.080.B.1 Lots shall be designed to contain a usable building area. If the building area would be difficult to develop, the lot shall be redesigned or eliminated, unless special conditions can be imposed on the approval which will ensure that the lot is developed properly. In addition to the slopes on the proposed Lot 1, the orientation of Lot 1 with the private drive that transects the lot further limits the buildable area and makes this a difficult site to develop. The proposed residence for Lot 1 shown on the preliminary development does not comply with the setbacks for Lot 1. A lot cannot be created through the subdivision process that would require a variance in order for it to be developed. June 20, 2019 Comment: The proposed residence has been removed from the preliminary development plans, which the response letter notes as addressing this issue. However, with the new lot configuration and now proposing to retain the swimming pool the development on Lot 1 would not comply with setbacks. See new comment 9 with regards to modification request. A modification request has been included in this submittal. In addition, the proposed residence now fits within the setbacks. c. Different layouts for subdividing this property were presented during the two pre- application style meetings over the last year. Given the review criteria in ECDC 20.75.080A.4 and 20.75.080.B.1, a different layout of the proposed subdivision should be given strong consideration. Otherwise, please demonstrate how the proposed layout complies with these criteria. PO Box 1478 ⬧ Everett, WA 98206 ⬧ Phone: (425) 303-9363 Fax: (425) 303-9362 ⬧ Email:info@insightengineering.net June 20, 2019 Comment: The response letter notes that Lot 2 has been enlarged and indicates that an 80-foot lot circle can also be located in the southeast corner of the property. While this is true for the lot layout in Figure 2 of the geotechnical report, the lot circle does not fit in the southeast corner with the lot configuration on the preliminary short plat and preliminary development plans. If the future building site is now proposed for the southeast corner of the property, please indicate so. A building area in the southeast corner would help address ECDC 20.75.080.A.4 and 20.75.080.B.1 as well as landslide hazard design standards ECDC 23.80.070.4.b. - 4.d. As noted in the attached Engineering comments and the previous comment from the Building Official, the geotechnical report will be sent out for peer review and the applicant will be responsible for the cost of peer review. The Geotech report has been updated. 7. Fire Comments: Addressed. 8. Please respond to the comments from Jeanie McConnell, Engineering Program Manager, provided in the attached memorandum. The easement referenced has been shown, and the pavement has been widened to 12 feet. 9. Modifications – ECDC 20.75.075: The proposal does not include retaining the swimming pool on Lot 1, which would result in the swimming pool and deck not meeting the zoning setbacks for the RS-12 zone. In the current configuration, Lot 1 would be considered a flag lot and only side setbacks would apply. The side setbacks for the RS-12 zone is 10 feet. Pursuant to ECDC 16.20.040.C, Uncovered and unenclosed porches, steps, patios, and decks may project into a required setback not more than one-third of the required setback, or four feet, whichever is less; provided, that they are no more than 30 inches above ground level at any point. The edge of the deck is approximately 3.3 feet from the new lot line between Lot 1 and 2. Pursuant to ECDC 19.00.025.X.1, the setbacks for swimming pools is measured to the inside face of the pool, which appears to be about 9 feet from the new lot line. If a proposed subdivision results in structures not complying with the required zoning setbacks, a modification requested must be submitted with the application. In accordance with ECDC 20.75.075, a modification request is evaluated with the variance criteria in Chapter 20.85 ECDC. The application fee for a modification request is $880 and a second notice of application will have to be issued for the modification request. Please see attached modification/variance request. Memorandum from Jeanie McConnell, Engineering Program Manager June 20, 2019 GENERAL 1. Ok PO Box 1478 ⬧ Everett, WA 98206 ⬧ Phone: (425) 303-9363 Fax: (425) 303-9362 ⬧ Email:info@insightengineering.net 2. Ok 3. Ok 4. June 20, 2019 – The driveway for existing lot 1 has been shown to cross the adjacent parcel (parcel # 00507000002200). Is there an existing access easement across this property? 12/6/2018 comment – Show existing access easement areas and existing pavement areas on one plan sheet. Will the existing and proposed pavement areas fall within existing easement areas? There is currently no written easement for the access. However, the access has remained the same since the property was constructed in 1961 5. Ok 6. June 20, 2019 – Pavement width shall be a minimum of 12-feet given only 2 lots will be taking access from the existing private road on the west side of the development. Revise the preliminary development plan to show required road widening. 12/6/2018 comment – Refer to South Snohomish County Fire District comment for access width requirements. The pavement width has been shown as 12’ wide and accounted for in the drainage calculations. Memorandum from Zach Richardson, Stormwater Engineer June 18, 2019 1. Please identify the overflow routes for both the pump system and infiltration system in the event of failure; address or mitigate impacts as needed to avoid creating erosion or flooding nuisances issues. In the event of failure, the infiltration system will overflow through the grated lid to drain to the existing driveway to follow the natural drainage path. The pump system will drain to the existing driveway to follow the natural drainage path along the shared driveway easement and down Vista Place. Please refer to Sheet C1.0. 2. Update plans to address the retrofit requirements of ECDC 18.30.060.D.5.b.i for any existing unmitigated impervious surfaces to remain; please provide a developed conditions exhibit to identify which areas are included for mitigation and show & sum the retrofit and new plus replaced areas separately. a. Appendix A suggests that all BMPs are infeasible for the existing roadway, however, it appears the proposed CB could easily be located in a location which would collect a portion of the existing access road and the proposed driveway (or add a second CB) and the same BMP can serve both surfaces. A part of the existing driveway has been accounted into the infiltration system. Please refer to the Developed Conditions Exhibit to identify the areas accounted into the infiltration system. PO Box 1478 ⬧ Everett, WA 98206 ⬧ Phone: (425) 303-9363 Fax: (425) 303-9362 ⬧ Email:info@insightengineering.net 3. Additional concerns for the proposal of infiltration in this critical geotechnical area have been raised and additional geotechnical review is being requested. Please address all comments provided by the geotechnical reviewer (consultant). Please send us all comments from outside consultants. We believe we have answered all concerns to date. Please feel free to contact me with any questions or comments you may have. Sincerely, Brian Kalab, P.E.