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City of Missoula, Montana Item to be Referred to City Council Committee Committee: Plat, Annexation and Zoning Item: Ranch Subdivision Plat Adjustment & Condition Amendments Date: August 7, 2009 Prepared by: John M. Newman, OPG Initiated by: Paul Druyvestein, DJ&A PAZ Action Required: Approval or denial of the Ranch Subdivision Plat Adjustment & Condition Amendments request. Recommended Motions: 1. THAT the proposed plat adjustment for Ranch Subdivision be APPROVED in accordance with Article 4- 7(4)(A) of the Missoula City Subdivision Regulations and subject to amended Condition No. 19. 2. THAT the Floodplain Administrator-recommended amendment to Condition No. 32 for Ranch Subdivision be APPROVED. Timeline: City Council’s Referral to committee: August 10, 2009 PAZ Committee Action: August 12, 2009 – Action Item City Council Action: August 17, 2009 (Consent Agenda or Committee Report) Deadline: Item does not carry a statutory deadline Background: This is a request from Stockyard Road Investments, represented by Paul Druyvestein of DJ&A, to adjust the approved preliminary plat of Ranch Subdivision (Attachment Ranch consists of 55 residential lots, a 0.5 acre park, and 0.97 acres of common area on 18.88 acres located approximately 0.5 miles north of Mullan Road on the east side of George Elmer Drive. The project was approved by the Missoula City Council on May 19, 2008 subject to thirty-eight (38) conditions of approval (Attachment In 2008, the City Council approved a plat adjustment creating 14 additional townhouse lots in an area of the subdivision previously occupied by duplex lots (Attachment Request: At this time the applicant proposes to adjust the approved preliminary plat of Ranch by providing facilities for detention and management of stormwater onsite (Attachment D) rather than offsite on an adjacent property under the applicant’s ownership. At the time of preliminary plat approval, the applicant proposed a stormwater management system designed to transport water volume resulting from the onsite increase in non-permeable, developed surface area to an offsite location. The applicant was required to dedicate a stormwater drainage easement on the adjacent site, legally described as Tract 8 of Certificate of Survey (COS) 3176 and under the applicant’s ownership, prior to final plat approval. However, in response to current economic conditions, the applicant would like to remove the drainage easement encumbrance from Tract 8 of COS 3176 so that the parcel may be sold or used for agriculture without preclusion. The applicant therefore proposes to install a stormwater detention basin, as well as dedicate a drainage easement, onsite ---PAGE BREAK--- in the northwest corner of Lot 1. As a result of installing the detention facility in this location, the applicant also proposes to decrease the number of multi-family units on Lot 1 from 13 to 12. The applicant has submitted a grading and drainage report (Attachment E) and accompanying plan (Attachment F) in support of the plat adjustment request. Consequent to the plat adjustment request is a Staff-recommended amendment to Condition of Approval No. 19. Condition No. 19 requires the applicant to record a drainage easement on Tract 8 of COS 3172, along with other requirements related to stormwater mitigation. The Staff-recommended revised condition is as follows: “The subdivider shall secure and record a stormwater drainage easement on Tract 8, COS #3176 the face of the Phase One final plat, subject to review and approval by Public Works prior to Phase One final plat approval. OPG shall review and approve any change in design to the subdivision layout resulting from new or revised drainage easements, prior to final plat approval. All drainage structures, including swales and basins, shall be in place prior to final plat approval. Drainage plans shall ensure that the 100-year twenty-four hour storm is detained with post development discharge from the detention basin limited to pre-development run-off rates. Grading, drainage, and erosion control plans shall be reviewed and approved by the Public Works Department prior to final plat approval of Phase One.” Agency Comment: The applicant’s request was summarized in an agency comment memo sent to City Engineering, the Floodplain Administrator, City-County Health, and County Public Works. City-County Health did not provide comment regarding the proposal. City Engineering comments outlined several concerns regarding detention basin design details, including outlet specifics and basin soil percolation (Attachment The comments expressed in City Engineering’s response, dated August 3, 2009, will be addressed by the applicant in the final design and installation stages, subject to review and approval by Engineering prior to final plat approval of Phase One per revised Condition No. 19. City Engineering comments did not expressly object to the proposal moving forward. The Floodplain Administrator had no adverse comments pertaining to the modified stormwater management plan (Attachment However, the Administrator commented, in a response dated July 16, 2009, that Condition No. 32 of the subdivision conditions of approval required revision. The condition currently requires a Letter of Map Revision (LOMR) removing lots in the northern portion of the subdivision from the FEMA designated floodplain to be submitted to OPG for review prior to filing the final plats for phases in which those lots are located. Particularly, lots within the floodplain are contained within Phases One and Two. The condition, however, states that lots within the floodplain are contained within Phases Two and Three. The Floodplain Administrator therefore recommended that Condition No. 32 be amended as follows: “If any of the lots are within the FEMA designated floodplain at the timing of the final plat approval, the subdivider shall submit a Letter of Map Revision (LOMR) removing all lots from the regulatory floodplain, subject to review and approval by the Floodplain Administrator prior to final plat approval of the first phase of development where the FEMA floodplain is shown on the property (currently Phases One and Three Two).” County Public Works commented, in a response dated July 16, 2009, that any changes to the stormwater management design for the subdivision, and the project itself more generally, should take into account Missoula County’s Grant Creek watershed and flood control project (Attachment The County has invested considerable funds in an effort to alleviate flooding issues in this area. The proposal to modify the stormwater management system and detain volume onsite presents less of an impact to the County project, as the new design is a greater distance from Grant Creek itself. Stormwater therefore has additional time to infiltrate with the proposed design. Staff Recommendations: Based upon agency comment and Article 4-7(4)(A) of the Missoula City Subdivision Regulations, staff recommends approval of the proposed plat adjustment subject to following revision of Condition No. 19: ---PAGE BREAK--- “The subdivider shall secure and record a stormwater drainage easement on Tract 8, COS #3176 the face of the Phase One final plat, subject to review and approval by Public Works prior to Phase One final plat approval. OPG shall review and approve any change in design to the subdivision layout resulting from new or revised drainage easements, prior to final plat approval. All drainage structures, including swales and basins, shall be in place prior to final plat approval. Drainage plans shall ensure that the 100-year twenty-four hour storm is detained with post development discharge from the detention basin limited to pre- development run-off rates. Grading, drainage, and erosion control plans shall be reviewed and approved by the Public Works Department prior to final plat approval of Phase One.” Additionally, staff recommends approval of the following Floodplain Administrator-recommended amendment to Condition No. 32 regarding the timing of submittal for the LOMR removing northern subdivision lots from the FEMA designated floodplain: “If any of the lots are within the FEMA designated floodplain at the timing of the final plat approval, the subdivider shall submit a Letter of Map Revision (LOMR) removing all lots from the regulatory floodplain, subject to review and approval by the Floodplain Administrator prior to final plat approval of the first phase of development where the FEMA floodplain is shown on the property (currently Phases One and Three Two).” Applicable Subdivision Regulations: Article 4-7(4) of the Missoula City Subdivision Regulations discusses adjustments to approved preliminary plats as follows: Plat Adjustments Minor adjustments may be approved by the governing body, in consultation with appropriate agencies, prior to the filing of the final plat. Minor adjustments are those changes which, in the governing body's opinion, may affect the precise dimensions of buildings and the location of buildings but not the basic character or arrangement of buildings, lots or blocks, the density of the development, the open space requirement or street design. Minor adjustments may require that a new plat be drawn but do not require that the plat be re-submitted for review. Major adjustments are those which, in the opinion of the governing body, substantially alter the basic design, density or open space requirements of the subdivision. Any changes which constitute a major adjustment shall require that a new application be re-submitted for review. Financial Implications: None foreseen Attachments: A. Applicant’s Request Letter dated June 8, 2009 B. Subdivision Approval Letter dated December 16, 2008 C. Approved Preliminary Plat D. Proposed Adjusted Preliminary Plat E. Grading and Drainage Report F. Grading and Drainage Plan G. Agency Comment (City Engineering, Floodplain Administrator, County Public Works)