Document Redmond_doc_f3ff7e1702

PRELIMINARY STORMWATER MANAGEMENT DESIGN REPORT Redmond City Center 16135 NE 85th Street Redmond, Washington 98052 Prepared for: Cosmos Development Company 11747 NE First Street, Suite 1300 Bellevue, WA 98005 Prepared by: 818 Stewart Street Seattle, WA 98101-3311 (206) 332-1900 Phone (888) 433-8130 Toll Free (206) 332-1600 Fax DCI Job No. 13012-0025 December 13, 2016 This report has been prepared by Staff of DCI Engineers under the direction of the professional engineer whose stamp and signature appears hereon. ---PAGE BREAK--- 16135 NE 85th Street DCI Engineers 2 CONTENTS Project Overview 3 Existing Conditions 3 Proposed Conditions 3 Minimum Requirements 5 MR 1: Preparation of Stormwater Site Plans 5 MR 2: Construction Stormwater Pollution Prevention 5 MR 3: Source Control of Pollution 5 MR 4: Preservation of Natural Drainage Systems and Outfalls 6 MR 5: On-site Stormwater Management 6 MR 6: Runoff Treatment 6 MR 7: Flow 6 MR 8: Wetlands Protection 6 MR 9: Operation and Maintenance 6 Analysis 6 APPENDIX Vicinity Map Site Plan Site Plan – Infiltration Sections Existing Conditions Basin Map Developed Conditions Basin Map Regional Stormwater Facilities Plan and Map Infiltration Basin Map WWHM Infiltration Calculations Figures 3.2 and 3.3 of the Stormwater Technical Notebook (2012) NRCS Soils Data Conveyance Map Geotechnical Engineering Report ---PAGE BREAK--- 16135 NE 85th Street DCI Engineers 3 PROJECT OVERVIEW The proposed project will construct two multi-story towers over underground parking on a 99,883sq. ft. (2.29-acre) site. The project site, tax parcel number [PHONE REDACTED], is located along the south side of NE 85th St, between 161st Ave NE and 164th Ave NE in Redmond, Washington. This preliminary Stormwater Site Plan was created using the 2012 City of Redmond Stormwater Technical Notebook, as adopted by the City of Redmond. This Stormwater Report provides stormwater requirements and design calculations for the project site. EXISTING CONDITIONS The site currently is occupied by a one story structure, associated parking, and vegetated landscaped areas around the perimeter of the site. An existing onsite storm system, consisting of catch basins and storm drain pipe sizes 4” through 15” are located onsite that collect and convey surface water runoff to an existing 24” metal storm drain located in the NE corner of the site. From here, the 24” storm drain connects to an existing 48” concrete drain located in NE 85th Street. The 48” storm drain runs along the centerline of NE 85th Street and drains towards the west. The existing site is generally flat, with little drop across the site. The majority of the surface water runoff is collected via the existing storm system prior to it being discharged from the site. No offsite flows enter the site. A geotechnical engineering report, dated July 21, 2015, was prepared by Earth Solutions NW, Inc. Per the report, ground water was encountered at the boring locations between depths of approximately 13 to 15 feet below existing ground surface. The geotech noted that the seasonal high ground water elevation at the site is 9.59-feet below ground surface at the boring well location. A copy of the report is included in the appendix to this report. PROPOSED CONDITIONS The proposed structure will contain two towers over a single podium, street-level retail and two levels of underground parking. The site will be accessed via a driveway off of NE 85th St. A drive aisle will provide a connection from NE 85th St to the underground parking located midsite. A fire access drive aisle will continue and be looped around the entire site. This drive aisle will not provide access to the residents and will strictly be used for fire access only. Therefore, the fire aisle is not considered pollution generating impervious surface (PGIS). Along the east side of the building is a proposed infiltration trench. A portion of the surface water runoff from the site containing non-polluting area will be routed to the infiltration area along the east side of the building. The infiltration facility will be located adjacent to the building, and offset from the property line minimum 5-feet. A deviation request will be submitted to the City to reduce the setback of the infiltration facility from the property line from 10-feet to 5-feet. ---PAGE BREAK--- 16135 NE 85th Street DCI Engineers 4 The area draining to the infiltration facility is outlined in the Infiltration Basin Map (see appendix). The infiltration facilities are summarized below and all calculations are included in the appendix: Trench Length (Feet) 64 Width (Feet) 6 Depth (feet) 2.3 Ex Elevation at Trench 40.0 Seasonal high Ground Water Elevation (per geotech report) 29.03 Elevation of bottom of Infiltration Trench 34.7 Elevation of top of Infiltration Trench 37.0 Cover over top of infiltration trench 3 Area draining to trench (acres) 0.69 Infiltration Rate 5 in/hr Percent Infiltrated 91.26% A stormwater collection system will convey all area drains and overflows from the infiltration trench to the existing 24” storm in the northeast corner of the site. The existing 24” storm drain connection from the project site to the existing 48” storm drain in NE 85th St will be re-used with this project. The project site is located within the City Center sub-basin Regional Stormwater Facility (see map in appendix). This is a fee in lieu of storm drainage basin. Therefore, no onsite flow control or water quality treatment is proposed for this site. As noted in the Redmond Comprehensive Storm Plan, the regional stormwater facility 362R, the 85th St Filter Vault, is located just upstream of the discharge to the Sammamish River. Per the Redmond Municipal Code Section 13.2.045, the capital facility charge associated with this basin is $5,436 per 2,000 square feet of impervious area. Per the code, a credit of 80 percent may be applied to the number of non-pollution generating imperious units that are managed by an approved private infiltration facility. ---PAGE BREAK--- 16135 NE 85th Street DCI Engineers 5 The following is a summary of the existing and proposed land cover and the average annual aquifer recharge, as calculated by WWHM: Impervious Pervious Average Annual Aquifer Recharge (Acre-Feet) PGIS Existing 1.83 Ac 0.46 Ac 0.89 Not Calculated Proposed 2.12 Ac 0.17 Ac 1.95 0.09 Ac MINIMUM REQUIREMENTS This project is classified as a Large Project because it will create more than 5000 sq. ft. of new impervious surface, and will be required to meet all of the following minimum requirements as applicable. As indicated in Figure 3.3, Minimum Requirements 1-9 will be required to be applied to the new and replaced impervious surfaces onsite. MR 1: Preparation of Stormwater Site Plans Stormwater site plans showing how stormwater will be collected and conveyed to the public storm sewer will be prepared in accordance with DOE and City of Redmond standards upon finalization of the site configuration. MR 2: Construction Stormwater Pollution Prevention The site construction plans will include TESC provisions with notes and details. A Construction Stormwater Pollution Prevention Plan also will be prepared. The proposed BMPs will include siltation barriers, an armored construction entrance, inlet protection and covering of exposed soil. Measures to handle dewatering also will be detailed. If the excavation will extend below the water table, the dewatering requirements are expected to be significant and the contractor is to prepare a dewatering plan. This project will require a Construction Stormwater General Permit (NPDES) from the Department of Ecology due to it being greater than one acre. MR 3: Source Control of Pollution The will include provisions for materials handling and pollution source control during construction. Any hazardous material releases shall be contained, cleaned up, and reported. The will provide details on how the following requirements will be met: • Monitoring plan. • Designated project contact. • Secondary containment. • Provisions to secure hazardous materials. • Response to leaking vehicles and equipment. • Practices and procedures regarding transfer of flammable and combustible liquids. • On-site cleanup materials and other containment and cleanup provisions. ---PAGE BREAK--- 16135 NE 85th Street DCI Engineers 6 The operation of the completed mixed use building is not expected to generate significant pollutants on an ongoing basis. MR 4: Preservation of Natural Drainage Systems and Outfalls The site as it currently exists is developed and does not have a natural drainage system. There are existing catch basin collection systems onsite that collect and convey the surface water runoff to the northeast corner of the site where it ties into an existing piped conveyance system. The proposed project will continue to collect and convey the runoff towards the existing discharge location. MR 5: On-site Stormwater Management The surface water runoff from the project will be collected and conveyed to the existing 24” storm drain where it will then be discharged from the site. It is anticipated that runoff from the vegetated landscaped areas surrounding the building will infiltrate into the existing soils, which are primarily comprised of native sands and gravel. The landscape areas will be enhanced with compost- amended soil, which will promote on-site runoff retention. MR 6: Runoff Treatment The project site is located within a fee in lieu of storm drainage basin. Therefore, no onsite water quality treatment is proposed for this site. The project will continue to discharge to the existing conveyance systems. MR 7: Flow Control The project site is located within a fee in lieu of storm drainage basin. Therefore, no onsite flow control is proposed for this site, as the existing detention vaults provides stormwater retention. MR 8: Wetlands Protection There are no wetlands on or near the project site. MR 9: Operation and Maintenance The building’s maintenance staff will be charged with monitoring the function of the on-site drainage facilities. If the final drainage design includes elements for which the Department of Ecology has identified maintenance guidelines, an Operations & Maintenance Manual will be prepared for maintenance staff. ANALYSIS The condition of the conveyances is in the purview of the City’s regional stormwater system. An existing 42” storm drain in NE 85th St drains towards the east. Approximately 300-feet of the site the storm drain pipe increases in size to a 54” pipe. The 54” storm drain continues to drain east where the ultimate outfall of the system is at the Sammamish River, approximately 0.35 miles west of the project site. See the Conveyance Map in the appendix. ---PAGE BREAK--- 16135 NE 85th Street DCI Engineers 7 APPENDIX Vicinity Map Site Plan Site Plan – Infiltration Sections Existing Conditions Basin Map Developed Conditions Basin Map Regional Stormwater Facilities Plan and Map Infiltration Basin Map WWHM Infiltration Calculations Figures 3.2 and 3.3 of the Stormwater Technical Notebook (2012) NRCS Soils Data Conveyance Map Geotechnical Engineering Report ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- Document1 1 October 16, 2006 CITY OF REDMOND REGIONAL STORMWATER FACILITIES PLAN The City of Redmond is proceeding with a major new initiative to retrofit the most urbanized portions of the City to improve water quality in its streams and to conform to current regulatory standards for stormwater management. This new initiative includes: 1. guiding new development by updating stormwater code requirements to: meet Washington State Department of Ecology (Ecology) standards, promote low impact development, and be protective of the drinking water aquifer; and 2. implementing and executing capital improvement projects to construct regional stormwater facilities at strategic locations in the City to provide the greatest improvement to stormwater in the most economical manner. The City intends to proceed with an aggressive schedule. 1.0 Alternative Approaches to Stormwater Management The City has reviewed state and federal requirements for stormwater management, considered alternative approaches to meeting those requirements, and has selected an innovative, flexible, and proactive plan for action. 1.1 Required Stormwater Facilities To meet federal Clean Water Act and Washington Department of Ecology requirements and to protect the environment, the City has adopted rules for management of stormwater flowing from new development and redevelopment project sites. These rules require implementation of flow control and water quality treatment of stormwater to protect streams and their inhabitants. Flow control requirements in Redmond generally consist of: • large stormwater detention ponds or vaults that cover about 10% of the newly developed or redeveloped area; or • if a project is near Lake Sammamish or the Sammamish River, an oversized conveyance pipe to carry flows all the way to the receiving water; or • if the soils are suitable and the site is not located within a groundwater protection area, a large infiltration pond or vault. Water quality treatment systems in Redmond generally take up much less space than flow control facilities and often include: • additional depth in stormwater detention ponds or vaults; or • biofiltration swales; or • constructed stormwater treatment wetlands; or • sand filters or cartridge filters in stormwater treatment vaults; or • a combination of two or more treatment methods. This does not carry the weight of the 2017 Stormwater Techncial Notebook. It is fairly dated. ---PAGE BREAK--- Document1 2 October 16, 2006 These stormwater flow control and water quality facilities may be established: 1) on individual development sites; 2) as large regional facilities; or 3) sites may be developed to minimize the need for such facilities. Each approach has its advantages and disadvantages. 1.2 The Individual Site Approach Using individual, on-site detention ponds or vaults for each development is the most common approach to stormwater management currently found in Redmond. Large residential plats typically use stormwater detention ponds. Commercial properties or properties with high property values, frequently opt to use stormwater detention vaults which are more expensive to construct, but may allow some beneficial uses such as parking or play areas on top. The owner or developer finance the design and construction of individual facilities and, initially, is responsible for all operation and maintenance. In Redmond, facilities included as part of large residential plats are turned over to the City for maintenance. The owners of commercial development and small residential plats retain ownership and maintenance of their facilities. However, the City remains ultimately responsible for these activities if the owner fails to carry out the necessary operation and maintenance. Small, individual facilities located outside of stream buffers are preferable because they generally cause the least disturbance to the natural system. In watersheds that include many small streams, individual site facilities are needed to be most protective of the flow regime in each of the small streams. There are disadvantages to individual site facilities. On-site facilities cost more per acre of development to construct and to maintain than regional facilities. Small facilities or underground vaults are more easily neglected because they are often out of sight and therefore out of mind. If neglected, a facility is less likely to achieve pollutant removal goals and may become an eyesore. One major limitation to the individual site approach is that it is triggered only by new development and redevelopment. In other words, if a section of the City does not redevelop, that area will not be upgraded to meet current standards. As the City faces the need to address water quality on a regional scale, there is a need to find a way to accommodate the need to retrofit those areas. With the City’s responsibilities at the regional level, a regional approach to stormwater management may be preferred. 1.3 The Regional Approach In newly developing areas, properties prime for redevelopment, or in portions of the City that need to be retrofitted with stormwater facilities, local governments may choose to install strategically located regional facilities within the watershed. If a regional pond is selected, it is advisable to use on-site controls for any industrial ---PAGE BREAK--- Document1 3 October 16, 2006 development within the regional pond drainage area. Regional facilities are not appropriate as in-stream facilities, but are appropriate for areas that are served by constructed stormwater conveyance systems (i.e. pipes and gutters). Regional facilities are significantly more cost-effective because it is easier and less expensive to build a single large facility than several small ones. The City is able to allocate staff to maintain a few large facilities, rather than review, inspect, and enforce maintenance of multiple private facilities. This results in an increased assurance of continued effectiveness of the facility. Additionally the high visibility of large, regional ponds helps to ensure they are well maintained. Through careful planning, combined with the City’s water quality monitoring program, regional facility construction can be prioritized to focus efforts on the most impaired waters. Construction of regional facilities affords an opportunity to retrofit larger portions of the City that do not have stormwater controls meeting current standards. Finally, adequately planned and designed regional ponds not only provide benefits for stormwater treatment and flood prevention, but provide aesthetic benefits and natural wildlife habitat. The main disadvantage to regional facilities is logistics. Locating and obtaining property for these large facilities is a challenge due to urban planning considerations and property costs. In most cases, the local government must provide capital construction funds for a regional facility, including the costs of land acquisition. However, if a developer is the first to build, that person could be required to construct the facility and later be compensated by upstream developers for the capital construction costs and annual maintenance expenditures. Conversely, an upstream developer may have to establish temporary control structures if the regional facility is not in place before construction. One good approach is for the City to establish a funding source like bonds and use developer contributions to help to repay those bonds as new projects within the basin are developed. 1.3 The Low Impact Development Approach Low Impact Development (LID) is an innovative stormwater management approach with a basic principle that is modeled after nature: manage rainfall at the source using small, site-based controls that are decentralized. The goal of LID is to mimic a site's predevelopment hydrology by using design techniques that infiltrate, filter, store, evaporate, and detain runoff close to its source. Techniques are based on the premise that stormwater management should not be seen as stormwater disposal. Instead of conveying and treating stormwater in large, costly, end-of-pipe facilities located at the bottom of drainage areas, LID addresses stormwater through small, more cost-effective landscape features located at the lot level. In rural settings, LID is the most preferred approach. In urban settings with high percentages of impervious surfaces, it can be challenging to design a site to infiltrate ---PAGE BREAK--- Document1 4 October 16, 2006 stormwater. (i.e. if a site is 90% impervious, there remains only 10% of the site to use for infiltration of the runoff that concentrates from the impervious areas.) With the right soil conditions, and development patterns, LID is an excellent approach. However, certain soil conditions can limit LID because LID is highly dependent upon infiltrating stormwater at the development site. In Redmond, there are two main concerns with the use of onsite infiltration for stormwater management: 1. Much of Redmond’s soils are composed of glacial till, a material with a poor capacity for infiltration. Much of the till soils in Redmond lie on hillsides. When development projects include attempts to infiltrate stormwater into till soils on steep slopes, there is a high likelihood that the stormwater will become a problem for an existing neighbor. Within Redmond’s urban growth boundary, any new development will likely have a nearby neighbor to impact. 2. On the valley floor of Redmond, the soils are ideal for infiltration. However, these soils are also the location of the City’s drinking water aquifer. Therefore, much of the valley floor is protected by City ordinance and State law as a “wellhead protection zone”. While infiltration of “clean” water from roofs and sidewalks is encouraged in wellhead protection zones, stormwater runoff from pollution generating surfaces like roads and parking lots is discouraged because of the potential for contamination of the groundwater resource. 1.4 The City of Redmond Proactive Approach Consistent with the City’s ethic and long term commitment to environmental protection, the City has taken the proactive approach of developing a Regional Stormwater Facilities Plan. This approach draws from the advantages of the individual approach, the regional approach, and the low impact development approach, in a manner that is integrated through: 1) revisions to its stormwater code that guides development; 2) careful management of operations and maintenance of existing facilities; and 3) a commitment to capital construction of new regional facilities. As is typical of most jurisdictions, requirements to construct stormwater flow control or water quality facilities in Redmond are triggered when properties submit for permits to develop or redevelop property. Since most of Redmond was developed prior to implementation of current stormwater requirements; and due to the high cost of redevelopment; most areas of Redmond will not be required to meet current stormwater standards until the existing properties develop or redevelop. This could take several decades for substantial areas of the City to comply with new and future more rigid standards. Redmond is not satisfied with the length of time it will take to bring the City’s stormwater conveyance and water quality facilities up to current codes or meet water quality objectives. ---PAGE BREAK--- Document1 5 October 16, 2006 As a part of the City’s commitment to stewardship of the streams within the City, the City has monitored water quality in stormwater and in the City’s streams for more than ten years. In 2004, that data was analyzed and it was determined that several of the City’s streams were impaired enough to be added to the State’s 303D list. This listing requires a plan by the City to address the areas of concern. The primary pollutants of concern in Redmond’s streams are: low dissolved oxygen, high temperature, and high fecal coliform. Additional monitoring has indicated high metals (copper, zinc, and lead) and hydrocarbons. In recognition of the need to improve water quality in the City’s streams, the City of Redmond’s Proactive Approach embraces a strategic combination of regional and low impact development approaches. By realizing the benefits gained in the regional approach and the performance achieved in LID, the City is able to proactively improve water quality and expedite compliance with state and federal stormwater initiatives. Also, as regulations change, the City will be poised to make a smooth transition to quickly upgrade its regional facilities to meet new standards. The City’s two-tiered approach includes: 1. strengthening the City’s stormwater code and development requirements, to require onsite retrofitting and encourage low impact development where appropriate; and 2. implementation of an aggressive capital improvement program to construct regional stormwater facilities that will retrofit key watersheds in the City and bring them up to current standards now. 2.0 STORMWATER CODE UPDATE The City is in the process of revising its stormwater code requirements through an update to the City’s Stormwater Technical Notebook (Stormwater Notebook). This update will include adoption of Ecology’s 2005 Stormwater Management Manual for Western Washington (Ecology Manual). Since the Ecology Manual is a state-wide document, it is necessary to clarify some of its requirements for direct application within the City of Redmond. The Stormwater Notebook identifies City-specific adjustments to development and redevelopment requirements to meet all the City’s long term goals for improvement to the environment. Several key areas are discussed below. 2.1 Redevelopment Retrofitting The Ecology Manual requires redevelopment projects to provide stormwater controls for redeveloped areas. However, in recognition of the need to retrofit the City to meet current stormwater standards, the City requires additional retrofitting in two ways: ---PAGE BREAK--- Document1 6 October 16, 2006 1. For redevelopment projects, stormwater facilities are required to be sized to provide flow control and treatment for the project area and an equal portion of the existing site (up to a maximum of twice the project area.) For road projects, this results in doubling the size of stormwater facilities, thereby retrofitting an equal portion of existing pavement. 2. For tenant improvement or other redevelopment projects that exceed the value of the existing site, the entire property is required to be retrofitted to meet current standards. These two policies are key components of the City’s approach to retrofitting the City to meet current standards, and are good examples of the City’s progressive approach to improving stormwater quality. 2.2 Low Impact Development The City’s new Stormwater Notebook includes a new emphasis on low impact development. A new section is being added to identify and encourage the preferred ways of implementing low impact development in Redmond, and clarifying what is required for review of LID developments. This section was prepared by a consultant working under a Department of Ecology grant to promote LID. The Stormwater Notebook also references the Puget Sound Action Team’s Low Impact Development Technical Guidance Manual for Puget Sound, and includes additional maintenance requirements for LID facilities. The Stormwater Notebook includes additional requirements for compost-amended soil. The City independently developed guidance for compost-amended soil that is now included in the Stormwater Notebook. This guidance is more specific and requires more of a developer investment than the guidance in the Ecology Manual. It has been demonstrated that the proper use of compost-amended soil greatly improves the infiltrating capacity of till soils and the capacity of those soils to hold water, thereby reducing stormwater runoff. They also are supportive of improved turf quality, resulting in a reduction in the use of fertilizers and pesticides by homeowners, thereby improving stormwater quality. To provide an incentive for use of compost-amended soil, areas of compost-amended turf that have: slope of at least 50 feet; and are made up of contiguous areas with a minimum area of 500 square feet; and are protected from vehicle traffic during construction; may be modeled as pasture for the purpose of sizing stormwater detention facilities. 2.3 Wellhead Protection Considerations In 2003, the City adopted a wellhead protection ordinance, as mandated by the Washington State Department of Health. This ordinance includes a prohibition against ---PAGE BREAK--- Document1 7 October 16, 2006 infiltration of unclean stormwater within wellhead protection zones. Contradictory to the wellhead protection requirements, the Ecology Manual requires infiltration of stormwater in outwash soils if direct discharge is not an option. However, the Ecology Manual includes a provision that if the groundwater is less than five feet deep, infiltration is not required. Instead, the soil is modeled as till for the purpose of sizing stormwater facilities. This common sense approach allows for a reasonable detention standard in outwash soils where infiltration is not an option. As a protective measure for the City’s shallow groundwater aquifer (less than five feet deep in many areas), on-site detention in Redmond’s Wellhead Protection Zones 1, 2, and 3 shall be designed using the assumption that outwash soils are till. (In effect, the applicant shall assume the groundwater is too high to accommodate infiltration, so Ecology’s alternative of modeling as till shall be used.) 2.4 Regional Facilities Plan If new development or redevelopment projects are located within a basin that drains to an existing or proposed regional stormwater facility, that development may be allowed (or required) to contribute toward the cost of constructing that facility in lieu of building onsite improvements. If the regional facility project has been constructed or is on the City’s Regional Facilities CIP List, then payment of the fee will be required and onsite improvements will not be required. The City will begin the Regional Facilities Plan by constructing the first facility during the summer of 2007. This proposed facility will retrofit a 22-acre portion of the 500-acre City Center to meet current standards for new development. This 22-acre retrofit will be the “starting balance” for a stormwater facility accounting system. As each new development is constructed in the City Center without building on-site facilities, the 22- acre balance will be reduced accordingly. In this way, the City will maintain a higher level of water quality in the common receiving water, the Sammamish River, than if development had gone forward with a site-by-site approach to stormwater management. Before the stormwater facility balance is reduced to zero, the City will construct the next retrofit facility, thereby continuing to stay ahead of stormwater requirements and providing continued benefit to the receiving waters. The City will manage its Regional Facilities Plan with certain conditions intended to protect local areas. Contribution in lieu of providing onsite flow control or water quality treatment is an option for new or redevelopment projects if the following conditions are met: 1. Allowing the contribution in lieu of providing onsite flow control or water quality shall not create an unsafe situation. 2. Appropriate onsite source control procedures are implemented. 3. The system shall have adequate capacity to convey the undetained flow for the required maximum return period storm events without ---PAGE BREAK--- Document1 8 October 16, 2006 causing or aggravating any flow-related problems such as flooding or erosion. 4. Sites draining to infiltration systems in wellhead protection zones will have additional restrictions. 5. Some onsite treatment may be required if the regional facility doesn’t meet all the requirements mandated for the development (i.e. if a development needs enhanced treatment and the regional facility only provides basic treatment, the regional facility may be the second part of a treatment train.) 6. A regional flow control project of the project site with available capacity for new development shall be on the City’s regional facility CIP list (as approved by the City Engineer). 7. The Natural Resources Division Manager or his/her designee approves the contribution in lieu of flow control as being consistent with the City’s goals and objectives of the regional facilities program. The amount of the contribution is proportionate to the amount of impervious area being added to the property. New impervious area that drains to the stormwater system is subject to a flow control fee. (This provides an incentive for infiltration of clean water from roofs and sidewalks.) New pollution generating impervious surfaces may not infiltrate, and are subject to a water quality fee. (This provides an incentive for site design that reduces the amount of pollution generating impervious surfaces.) 3.0 REGIONAL FACILITIES CAPITAL CONSTRUCTION PLAN A major component of the City’s initiative to rapidly improve the water quality of the streams in Redmond is construction of several key regional facilities. By moving forward with design and construction of these facilities, the City will make a very large investment in the health of its streams. 3.1 City Center Redmond’s City Center is made up of about 500 acres of commercial and residential development that drains to the Sammamish River. To retrofit this watershed, the City is planning construction of six regional facilities (see figure): • Redmond Way Stormwater Trunk. Construct a new 6,000 lf direct discharge stormwater trunk from the east end of downtown Redmond to the River. • Redmond Way Stormwater Treatment Facility. Construct a stormwater treatment wetland or cartridge filter system to provide enhanced treatment for the water quality storm. • Leary Way Stormwater Treatment Wetland. Expand an existing bioswale into a stormwater treatment wetland to retrofit the subbasin for enhanced treatment. • McRedmond Park filter vault. Construct a cartridge filter system to provide enhanced treatment for the water quality storm. • Bear Creek filter vault. Construct a cartridge filter vault to treat and divert flow from a portion of the Redmond Way Stormwater Trunk into Bear Creek. ---PAGE BREAK--- Document1 9 October 16, 2006 • 85th Street Water Quality. Construct a filter vault on the City campus to provide enhanced treatment for the water quality storm. The City’s initial push forward with the Regional Facilities Plan will be to finance these six projects, at an estimated $40 million. The first project will be constructed in the summer of 2007 by borrowing from the Stormwater Utility’s capital improvement fund. 3.2 Overlake Redmond’s Overlake neighborhood includes a 150-acre area of commercial development that drains into Bellevue. The City has identified two preferred locations for large regional stormwater ponds that would provide stormwater treatment and detention before the stormwater leaves Redmond’s City limits and flows into Bellevue. It should be noted that Redmond represents a very small portion of the 10,870 acre Kelsey Creek basin. The City of Bellevue provides primary stewardship for this basin. All of Redmond’s contribution to the basin flows into Bellevue’s municipal stormwater conveyance system, which has discharges to waters of the state that are regulated by the Washington State Department of Ecology. As a good neighbor, the City is committed to meeting City of Bellevue standards for detention and water quality. As an environmental steward, Redmond is committed to bringing the entire watershed up to current standards. To meet these two goals, projects within this watershed will have two options. The first option will be to design the project to meet all the standard requirements of the Stormwater Technical Notebook. The second option will be to design the project to meet City of Bellevue standards for detention and water quality and to make a proportionate contribution toward construction of the City’s proposed regional facilities. With this approach, stormwater will be managed to meet or exceed the requirements of the primary basin steward (Bellevue) while using developer contributions to take steps to retrofit the watershed to meet current City of Redmond standards. 3.3 City-Wide With completion of the key regional facilities described above, the City will continue its efforts in other portions of the City. Initial estimates have identified new proposed facilities at a cost of about $60 million to complete. 3.4 Council Support City staff presented the Regional Facilities Plan to the Redmond City Council’s Planning & Public Works Committee. The committee endorsed the Regional Facilities Plan and the full Council has embraced the philosophy and is supportive of the concept. Council is now considering the final terms for financing the plan. ---PAGE BREAK--- Document1 10 October 16, 2006 3.5 Financing The cost for the City Center facilities is estimated at $40 million. The City will obtain bonds in that amount to fund the program. The bonds will be repaid from the City’s Stormwater Utility Fund and also from developer contributions as part of the “fee in lieu of” program. Once formal approval of the financial plan is achieved, the City will leverage existing balances in the Stormwater Utility’s Capital Improvement Fund to begin design and construction of the proposed facilities. 4.0 REGIONAL STORMWATER FACILITIES PLAN – IMPLEMENTATION SCHEDULE In the interest of quickly advancing this proactive approach to stormwater management, the City has an aggressive schedule for updating its stormwater code and implementing its Regional Facilities Capital Construction Plan. Jan-Sep 2006 Update Stormwater Notebook Identify proposed regional facilities Sep 2006 Complete internal review of Stormwater Notebook Reach out to Ecology for feedback about the Regional Facilities Plan Oct 2006 Share draft Stormwater Notebook with the public. City approval of Stormwater Notebook Seek Council approval for funding of Regional Facilities Plan Nov 2006 Publish Stormwater Notebook Develop accounting protocols for Regional Facilities Plan Jan 2007 Stormwater Notebook becomes effective Begin design of City Center regional facilities Jul 2007 Obtain $40 million bonds to fund Regional Facilities Plan. Award construction contract for first facility for summer construction Future Construction of facilities in City Center, Overlake, and beyond ---PAGE BREAK--- Document1 11 October 16, 2006 Figure: Regional Facilities Capital Construction Map Notes: • Each facility is designed to provide enhanced treatment for its associated drainage area. All new development located within the highlighted area will contribute toward the cost of construction of these six regional facilities. Facilities will be sized to treat the water quality design storm. • For the filter vaults, it is hoped that the Aquaswirl / Aquafilter vault system will be approved for enhanced treatment. If this doesn’t work out, the City will proceed with a wetvault / StormFilter vault alternative. • The six regional facilities will be: 1. McRedmond Filter Vault: enhanced treatment of 22 Acres of commercial downtown. $1.6M. 2. Leary Stormwater Treatment Wetland: enhanced treatment of 16 Acres of commercial downtown. $500K 3. Redmond Way Filter Vault: enhanced treatment of 209 Acres of commercial downtown and residential neighborhoods draining through the new Redmond Way Storm Trunk. $4.6M. A stormwater treatment wetland option is under consideration pending property issues. 4. 85th Street Filter Vault: enhanced treatment of 230 Acres of commercial downtown, multifamily, and residential neighborhoods. $7.6M. 5. Safeway Filter Vault: enhanced treatment of the water quality storm from 15 Acres or residential and commercial areas. The water quality storm will be treated and discharged to Bear Creek. Higher flows of untreated stormwater will go to the Redmond Way Storm Trunk. $712K 6. Redmond Way Storm Trunk: New storm trunk sized to convey 100-year storm to the river. $22.5M. PROJECT SITE ---PAGE BREAK--- ---PAGE BREAK--- WWHM2012 PROJECT REPORT ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:03:23 AM Page 2 General Model Information Project Name: 2015-1110_infiltration Site Name: Redmond City Center Site Address: NE 85th St City: Redmond Report Date: 11/10/2015 Gage: Seatac Data Start: 1948/10/01 Data End: 2009/09/30 Timestep: Hourly Precip Scale: 1.00 Version: 2015/08/19 POC Thresholds Low Flow Threshold for POC1: 50 Percent of the 2 Year High Flow Threshold for POC1: 50 Year Not applicable: No detention ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:03:23 AM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass: No GroundWater: No Pervious Land Use Acres A B, Lawn, Flat 0.46 Pervious Total 0.46 Impervious Land Use Acres DRIVEWAYS FLAT 1.83 Impervious Total 1.83 Basin Total 2.29 Element Flows To: Surface Interflow Groundwater Existing Land Cover for entire site ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:03:23 AM Page 4 Mitigated Land Use Basin Bypass: No GroundWater: No Pervious Land Use Acres Pervious Total 0 Impervious Land Use Acres DRIVEWAYS FLAT 0.69 Impervious Total 0.69 Basin Total 0.69 Element Flows To: Surface Interflow Groundwater Infiltration Trench Infiltration Trench ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:03:23 AM Page 5 Basin 'C'-Bypasses Infiltration System Bypass: Yes GroundWater: No Pervious Land Use Acres A B, Lawn, Flat 0.17 Pervious Total 0.17 Impervious Land Use Acres DRIVEWAYS FLAT 1.43 Impervious Total 1.43 Basin Total 1.6 Element Flows To: Surface Interflow Groundwater Basin that bypasses infiltration facilities ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:03:23 AM Page 7 Mitigated Routing Infiltration Trench Bottom Length: 64.00 ft. Bottom Width: 6.00 ft. Trench bottom slope 1: 0.0001 To 1 Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer: 2.3 Pour Space of material for first layer: 0.3 Material thickness of second layer: 0 Pour Space of material for second layer: 0 Material thickness of third layer: 0 Pour Space of material for third layer: 0 Infiltration On Infiltration rate: 5 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft): 98.883 Total Volume Through Riser (ac-ft): 9.47 Total Volume Through Facility (ac-ft): 108.353 Percent Infiltrated: 91.26 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 2.3 ft. Riser Diameter: 8 in. Element Flows To: Outlet 1 Outlet 2 Gravel Trench Bed Hydraulic Table Stage(ft) Area(ac) Volume(ac-ft) Discharge(cfs) Infilt(cfs) 0.0000 0.008 0.000 0.000 0.000 0.0278 0.008 0.000 0.000 0.044 0.0556 0.008 0.000 0.000 0.044 0.0833 0.008 0.000 0.000 0.044 0.1111 0.008 0.000 0.000 0.044 0.1389 0.008 0.000 0.000 0.044 0.1667 0.008 0.000 0.000 0.044 0.1944 0.008 0.000 0.000 0.044 0.2222 0.008 0.000 0.000 0.044 0.2500 0.008 0.000 0.000 0.044 0.2778 0.008 0.000 0.000 0.044 0.3056 0.008 0.000 0.000 0.044 0.3333 0.008 0.000 0.000 0.044 0.3611 0.008 0.001 0.000 0.044 0.3889 0.008 0.001 0.000 0.044 0.4167 0.008 0.001 0.000 0.044 0.4444 0.008 0.001 0.000 0.044 0.4722 0.008 0.001 0.000 0.044 0.5000 0.008 0.001 0.000 0.044 0.5278 0.008 0.001 0.000 0.044 0.5556 0.008 0.001 0.000 0.044 0.5833 0.008 0.001 0.000 0.044 0.6111 0.008 0.001 0.000 0.044 0.6389 0.008 0.001 0.000 0.044 ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:03:23 AM Page 8 0.6667 0.008 0.001 0.000 0.044 0.6944 0.008 0.001 0.000 0.044 0.7222 0.008 0.001 0.000 0.044 0.7500 0.008 0.002 0.000 0.044 0.7778 0.008 0.002 0.000 0.044 0.8056 0.008 0.002 0.000 0.044 0.8333 0.008 0.002 0.000 0.044 0.8611 0.008 0.002 0.000 0.044 0.8889 0.008 0.002 0.000 0.044 0.9167 0.008 0.002 0.000 0.044 0.9444 0.008 0.002 0.000 0.044 0.9722 0.008 0.002 0.000 0.044 1.0000 0.008 0.002 0.000 0.044 1.0278 0.008 0.002 0.000 0.044 1.0556 0.008 0.002 0.000 0.044 1.0833 0.008 0.002 0.000 0.044 1.1111 0.008 0.002 0.000 0.044 1.1389 0.008 0.003 0.000 0.044 1.1667 0.008 0.003 0.000 0.044 1.1944 0.008 0.003 0.000 0.044 1.2222 0.008 0.003 0.000 0.044 1.2500 0.008 0.003 0.000 0.044 1.2778 0.008 0.003 0.000 0.044 1.3056 0.008 0.003 0.000 0.044 1.3333 0.008 0.003 0.000 0.044 1.3611 0.008 0.003 0.000 0.044 1.3889 0.008 0.003 0.000 0.044 1.4167 0.008 0.003 0.000 0.044 1.4444 0.008 0.003 0.000 0.044 1.4722 0.008 0.003 0.000 0.044 1.5000 0.008 0.004 0.000 0.044 1.5278 0.008 0.004 0.000 0.044 1.5556 0.008 0.004 0.000 0.044 1.5833 0.008 0.004 0.000 0.044 1.6111 0.008 0.004 0.000 0.044 1.6389 0.008 0.004 0.000 0.044 1.6667 0.008 0.004 0.000 0.044 1.6944 0.008 0.004 0.000 0.044 1.7222 0.008 0.004 0.000 0.044 1.7500 0.008 0.004 0.000 0.044 1.7778 0.008 0.004 0.000 0.044 1.8056 0.008 0.004 0.000 0.044 1.8333 0.008 0.004 0.000 0.044 1.8611 0.008 0.004 0.000 0.044 1.8889 0.008 0.005 0.000 0.044 1.9167 0.008 0.005 0.000 0.044 1.9444 0.008 0.005 0.000 0.044 1.9722 0.008 0.005 0.000 0.044 2.0000 0.008 0.005 0.000 0.044 2.0278 0.008 0.005 0.000 0.044 2.0556 0.008 0.005 0.000 0.044 2.0833 0.008 0.005 0.000 0.044 2.1111 0.008 0.005 0.000 0.044 2.1389 0.008 0.005 0.000 0.044 2.1667 0.008 0.005 0.000 0.044 2.1944 0.008 0.005 0.000 0.044 2.2222 0.008 0.005 0.000 0.044 2.2500 0.008 0.006 0.000 0.044 ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:03:23 AM Page 9 2.2778 0.008 0.006 0.000 0.044 2.3056 0.008 0.006 0.002 0.044 2.3333 0.008 0.006 0.043 0.044 2.3611 0.008 0.006 0.106 0.044 2.3889 0.008 0.007 0.184 0.044 2.4167 0.008 0.007 0.273 0.044 2.4444 0.008 0.007 0.367 0.044 2.4722 0.008 0.007 0.460 0.044 2.5000 0.008 0.008 0.547 0.044 ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:03:23 AM Page 10 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area: 0.46 Total Impervious Area: 1.83 Mitigated Landuse Totals for POC #1 Total Pervious Area: 0.17 Total Impervious Area: 2.12 Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.470491 5 year 0.592813 10 year 0.677467 25 year 0.788864 50 year 0.875215 100 year 0.964559 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.478331 5 year 0.618303 10 year 0.717108 25 year 0.849209 50 year 0.953056 100 year 1.061703 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.467 0.495 1950 0.712 0.729 1951 0.465 0.481 1952 0.408 0.426 1953 0.367 0.364 1954 0.436 0.435 1955 0.466 0.500 1956 0.450 0.478 1957 0.509 0.538 1958 0.463 0.464 ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:03:42 AM Page 11 1959 0.356 0.364 1960 0.441 0.463 1961 0.396 0.373 1962 0.400 0.352 1963 0.380 0.375 1964 0.451 0.479 1965 0.404 0.396 1966 0.400 0.416 1967 0.602 0.646 1968 0.681 0.716 1969 0.364 0.373 1970 0.400 0.413 1971 0.390 0.367 1972 0.563 0.593 1973 0.365 0.379 1974 0.400 0.377 1975 0.525 0.547 1976 0.362 0.376 1977 0.468 0.487 1978 0.606 0.629 1979 0.599 0.585 1980 0.493 0.492 1981 0.549 0.589 1982 0.748 0.826 1983 0.555 0.594 1984 0.416 0.376 1985 0.397 0.412 1986 0.481 0.509 1987 0.693 0.705 1988 0.334 0.334 1989 0.419 0.381 1990 0.755 0.821 1991 0.705 0.766 1992 0.414 0.428 1993 0.286 0.286 1994 0.343 0.303 1995 0.427 0.439 1996 0.509 0.526 1997 0.488 0.505 1998 0.522 0.498 1999 0.981 1.076 2000 0.505 0.517 2001 0.442 0.463 2002 0.502 0.536 2003 0.454 0.403 2004 0.876 0.960 2005 0.415 0.435 2006 0.343 0.337 2007 0.832 0.788 2008 0.693 0.756 2009 0.500 0.524 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.9807 1.0756 2 0.8757 0.9599 3 0.8317 0.8263 ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:03:42 AM Page 12 4 0.7553 0.8209 5 0.7482 0.7882 6 0.7116 0.7661 7 0.7050 0.7559 8 0.6931 0.7294 9 0.6929 0.7160 10 0.6805 0.7048 11 0.6062 0.6461 12 0.6016 0.6295 13 0.5991 0.5942 14 0.5630 0.5929 15 0.5550 0.5889 16 0.5495 0.5852 17 0.5255 0.5465 18 0.5222 0.5384 19 0.5089 0.5360 20 0.5086 0.5264 21 0.5051 0.5240 22 0.5023 0.5172 23 0.5003 0.5093 24 0.4929 0.5050 25 0.4882 0.5005 26 0.4811 0.4981 27 0.4678 0.4952 28 0.4674 0.4923 29 0.4664 0.4873 30 0.4654 0.4812 31 0.4631 0.4795 32 0.4544 0.4777 33 0.4515 0.4638 34 0.4500 0.4631 35 0.4419 0.4625 36 0.4412 0.4388 37 0.4363 0.4350 38 0.4267 0.4349 39 0.4188 0.4276 40 0.4157 0.4263 41 0.4153 0.4157 42 0.4135 0.4134 43 0.4083 0.4116 44 0.4037 0.4028 45 0.4001 0.3964 46 0.3999 0.3811 47 0.3998 0.3790 48 0.3996 0.3773 49 0.3970 0.3764 50 0.3958 0.3760 51 0.3900 0.3748 52 0.3802 0.3726 53 0.3672 0.3725 54 0.3645 0.3673 55 0.3639 0.3644 56 0.3617 0.3642 57 0.3556 0.3517 58 0.3434 0.3366 59 0.3427 0.3343 60 0.3337 0.3032 61 0.2863 0.2858 ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:04:04 AM Page 19 Recharge Predeveloped POC #1 Recharge Predeveloped Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total 1948 0.012 0.112 0.161 .29 1949 0.014 0.162 0.088 0.016 0.026 0.005 0.006 0.001 0.008 0.046 0.16 0.144 .68 1950 0.271 0.176 0.244 0.066 0.006 0.004 0.014 0.033 0.033 0.145 0.224 0.221 1.44 1951 0.218 0.283 0.093 0.016 0.025 0. 0.005 0.009 0.017 0.115 0.138 0.107 1.03 1952 0.133 0.064 0.079 0.045 0.01 0.008 0.005 0.004 0.001 0.006 0.008 0.09 .45 1953 0.362 0.106 0.088 0.032 0.045 0.03 0.01 0.009 0.041 0.094 0.194 0.17 1.18 1954 0.262 0.133 0.05 0.058 0.036 0.041 0.031 0.014 0.019 0.03 0.185 0.143 1.00 1955 0.085 0.12 0.077 0.088 0.037 0.014 0.026 0.001 0.013 0.131 0.247 0.301 1.14 1956 0.282 0.053 0.138 0.005 0.011 0.047 0.004 0.009 0.024 0.139 0.036 0.151 .90 1957 0.055 0.163 0.171 0.042 0.021 0.013 0.015 0.021 0.004 0.052 0.061 0.142 .76 1958 0.249 0.164 0.045 0.08 0.013 0.012 0. 0. 0.004 0.049 0.197 0.207 1.02 1959 0.245 0.106 0.103 0.09 0.028 0.029 0.013 0.005 0.069 0.052 0.213 0.204 1.16 1960 0.164 0.125 0.106 0.062 0.05 0.009 0. 0.019 0.013 0.073 0.212 0.098 .93 1961 0.231 0.295 0.122 0.05 0.07 0.007 0.016 0.007 0.001 0.036 0.098 0.142 1.08 1962 0.057 0.054 0.065 0.041 0.038 0.005 0.009 0.025 0.024 0.073 0.244 0.147 .78 1963 0.061 0.124 0.09 0.071 0.021 0.029 0.018 0.005 0.002 0.085 0.262 0.165 .93 1964 0.313 0.042 0.064 0.033 0.01 0.095 0.013 0.015 0.036 0.013 0.255 0.16 1.05 1965 0.155 0.116 0.007 0.085 0.033 0.01 0.003 0.025 0.004 0.036 0.108 0.202 .78 1966 0.154 0.055 0.128 0.048 0.026 0.016 0.021 0.002 0.012 0.036 0.161 0.238 .90 1967 0.291 0.076 0.093 0.051 0.002 0.049 0. 0. 0.003 0.088 0.056 0.123 .83 1968 0.195 0.184 0.143 0.022 0.032 0.069 0.013 0.085 0.035 0.094 0.156 0.261 1.29 1969 0.177 0.097 0.048 0.085 0.069 0.018 0.002 0.002 0.085 0.02 0.048 0.15 .80 1970 0.236 0.064 0.08 0.07 0.024 0.001 0.005 0.002 0.014 0.029 0.104 0.229 .86 1971 0.153 0.122 0.204 0.055 0.019 0.041 0.009 0.005 0.054 0.073 0.138 0.19 1.06 1972 0.221 0.249 0.208 0.1 0.007 0.038 0.029 0.016 0.069 0.011 0.075 0.254 1.28 1973 0.114 0.047 0.029 0.024 0.034 0.045 0. 0. 0.012 0.043 0.198 0.248 .79 1974 0.242 0.12 0.168 0.062 0.015 0.029 0.03 0. 0.001 0.019 0.105 0.167 .96 1975 0.168 0.17 0.068 0.059 0.018 0.009 0. 0.072 0. 0.175 0.132 0.229 1.10 1976 0.169 0.142 0.06 0.029 0.025 0.01 0.02 0.05 0.02 0.034 0.011 0.036 .61 1977 0.034 0.031 0.082 0. 0.066 0.011 0.002 0.035 0.033 0.04 0.126 0.182 .64 1978 0.116 0.101 0.06 0.099 0.035 0.01 0.024 0.006 0.104 0.015 0.153 0.03 .75 1979 0.055 0.148 0.035 0.008 0.012 0.001 0.01 0.003 0.015 0.048 0.038 0.326 .70 1980 0.118 0.15 0.043 0.08 0.019 0.031 0.004 0.004 0.012 0.015 0.162 0.207 .84 1981 0.062 0.132 0.05 0.025 0.021 0.045 0.027 0. 0.047 0.144 0.103 0.162 .82 1982 0.158 0.242 0.1 0.049 0.004 0.018 0.004 0.004 0.008 0.053 0.122 0.192 .95 1983 0.206 0.135 0.098 0.021 0.05 0.034 0.044 0.031 0.031 0.019 0.202 0.139 1.01 1984 0.095 0.108 0.097 0.058 0.065 0.062 0.001 0. 0.007 0.018 0.18 0.144 .84 1985 0.013 0.068 0.057 0.018 0.009 0.062 0. 0.002 0.008 0.079 0.104 0.048 .47 1986 0.239 0.131 0.045 0.021 0.028 0.006 0.015 0. 0.008 0.066 0.204 0.105 .87 1987 0.186 0.056 0.171 0.063 0.057 0. 0.001 0.001 0.004 0.001 0.029 0.142 .71 1988 0.103 0.01 0.09 0.076 0.058 0.031 0.006 0.001 0.008 0.021 0.196 0.089 .69 1989 0.069 0.097 0.147 0.071 0.051 0.013 0.005 0.006 0.001 0.023 0.127 0.126 .74 1990 0.273 0.113 0.06 0.047 0.033 0.063 0.009 0.003 0. 0.077 0.28 0.106 1.06 1991 0.134 0.143 0.131 0.177 0.02 0.02 0.004 0.035 0. 0.011 0.106 0.08 .86 1992 0.217 0.084 0.036 0.087 0. 0.021 0.011 0.009 0.004 0.012 0.095 0.096 .67 1993 0.095 0.006 0.137 0.135 0.065 0.054 0.012 0. 0. 0.012 0.029 0.099 .64 1994 0.057 0.117 0.076 0.046 0.016 0.016 0. 0.002 0.007 0.033 0.126 0.23 .73 1995 0.128 0.147 0.107 0.039 0.013 0.023 0.024 0.027 0.004 0.05 0.252 0.184 1.00 1996 0.238 0.276 0.061 0.175 0.03 0.013 0.005 0.03 0.017 0.09 0.102 0.287 1.32 1997 0.216 0.049 0.256 0.117 0.029 0.025 0.006 0.011 0.048 0.14 0.114 0.074 1.09 ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:04:08 AM Page 20 1998 0.253 0.106 0.109 0.018 0.037 0.018 0. 0.002 0.003 0.036 0.292 0.276 1.15 1999 0.216 0.223 0.094 0.019 0.03 0.03 0.021 0.006 0. 0.027 0.24 0.141 1.05 2000 0.099 0.155 0.066 0.021 0.054 0.029 0. 0.002 0.005 0.036 0.061 0.053 .58 2001 0.059 0.047 0.052 0.063 0.024 0.048 0.015 0.026 0.006 0.038 0.229 0.168 .77 2002 0.196 0.126 0.075 0.114 0.005 0.03 0.011 0. 0. 0.003 0.044 0.137 .74 2003 0.221 0.042 0.165 0.052 0.013 0.003 0. 0. 0.001 0.146 0.181 0.106 .93 2004 0.177 0.066 0.041 0.002 0.05 0.004 0. 0.037 0.035 0.052 0.066 0.111 .64 2005 0.108 0.024 0.091 0.082 0.066 0.024 0.016 0.001 0.004 0.024 0.11 0.183 .73 2006 0.354 0.072 0.038 0.061 0.023 0.032 0. 0. 0.008 0.013 0.398 0.231 1.23 2007 0.189 0.093 0.113 0.002 0.025 0.016 0.021 0.007 0.045 0.062 0.084 0.256 .91 2008 0.121 0.037 0.085 0.023 0.009 0.029 0.003 0.035 0.006 0.025 0.148 0.105 .63 2009 0.151 0.034 0.096 0.079 0.084 0. 0. 0.008 0.015 .47 ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:04:08 AM Page 21 Recharge Mitigated POC #1 Recharge Mitigated Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total 1948 0.092 0.343 0.375 .81 1949 0.03 0.323 0.19 0.035 0.057 0.013 0.02 0.007 0.052 0.162 0.393 0.303 1.59 1950 0.53 0.352 0.427 0.138 0.012 0.007 0.036 0.069 0.11 0.326 0.468 0.429 2.91 1951 0.417 0.463 0.187 0.032 0.052 0. 0.011 0.035 0.079 0.306 0.31 0.241 2.13 1952 0.261 0.139 0.165 0.096 0.022 0.018 0.014 0.02 0.006 0.054 0.049 0.286 1.13 1953 0.793 0.225 0.176 0.066 0.096 0.067 0.025 0.033 0.127 0.253 0.435 0.351 2.65 1954 0.496 0.259 0.102 0.122 0.074 0.089 0.07 0.041 0.063 0.095 0.431 0.302 2.14 1955 0.185 0.189 0.159 0.189 0.08 0.03 0.067 0.009 0.059 0.356 0.492 0.552 2.37 1956 0.541 0.105 0.282 0.011 0.024 0.101 0.01 0.027 0.106 0.377 0.076 0.301 1.96 1957 0.119 0.35 0.356 0.09 0.045 0.028 0.029 0.063 0.022 0.178 0.164 0.327 1.77 1958 0.495 0.331 0.093 0.168 0.029 0.023 0. 0. 0.029 0.168 0.444 0.444 2.23 1959 0.485 0.21 0.207 0.19 0.058 0.062 0.03 0.018 0.214 0.13 0.404 0.367 2.37 1960 0.32 0.218 0.219 0.128 0.105 0.019 0. 0.063 0.042 0.211 0.46 0.195 1.98 1961 0.472 0.539 0.244 0.101 0.139 0.015 0.039 0.026 0.012 0.158 0.251 0.322 2.32 1962 0.114 0.116 0.14 0.088 0.086 0.012 0.025 0.082 0.096 0.211 0.534 0.306 1.81 1963 0.119 0.249 0.19 0.149 0.046 0.063 0.044 0.017 0.008 0.246 0.604 0.322 2.06 1964 0.622 0.083 0.134 0.068 0.02 0.207 0.03 0.037 0.094 0.035 0.537 0.34 2.21 1965 0.316 0.235 0.015 0.157 0.061 0.022 0.008 0.093 0.016 0.138 0.285 0.452 1.80 1966 0.305 0.116 0.267 0.103 0.056 0.041 0.053 0.015 0.062 0.144 0.39 0.487 2.04 1967 0.524 0.151 0.189 0.103 0.003 0.106 0. 0. 0.027 0.309 0.145 0.282 1.84 1968 0.423 0.352 0.297 0.047 0.067 0.155 0.03 0.204 0.092 0.235 0.328 0.493 2.72 1969 0.358 0.194 0.097 0.18 0.13 0.043 0.005 0.006 0.297 0.053 0.104 0.355 1.82 1970 0.497 0.135 0.162 0.138 0.056 0.002 0.02 0.009 0.1 0.124 0.284 0.482 2.01 1971 0.313 0.255 0.416 0.101 0.039 0.087 0.019 0.015 0.171 0.193 0.305 0.385 2.30 1972 0.44 0.416 0.353 0.206 0.015 0.074 0.066 0.049 0.185 0.031 0.195 0.559 2.59 1973 0.219 0.095 0.065 0.054 0.075 0.099 0. 0.001 0.084 0.16 0.462 0.53 1.84 1974 0.485 0.244 0.33 0.127 0.031 0.063 0.069 0. 0.002 0.086 0.306 0.335 2.08 1975 0.343 0.325 0.14 0.124 0.038 0.021 0.001 0.2 0. 0.449 0.283 0.462 2.38 1976 0.327 0.289 0.125 0.06 0.054 0.021 0.043 0.136 0.055 0.091 0.032 0.096 1.33 1977 0.083 0.076 0.196 0. 0.165 0.029 0.008 0.155 0.114 0.118 0.285 0.37 1.60 1978 0.244 0.212 0.126 0.205 0.076 0.023 0.067 0.022 0.249 0.024 0.348 0.069 1.66 1979 0.124 0.321 0.069 0.016 0.027 0.002 0.034 0.029 0.078 0.181 0.106 0.649 1.64 1980 0.247 0.315 0.089 0.168 0.041 0.071 0.009 0.016 0.049 0.056 0.403 0.429 1.89 1981 0.133 0.28 0.105 0.051 0.045 0.091 0.058 0. 0.152 0.264 0.211 0.344 1.73 1982 0.311 0.48 0.203 0.103 0.009 0.047 0.01 0.019 0.049 0.16 0.3 0.405 2.10 1983 0.395 0.278 0.2 0.044 0.109 0.067 0.108 0.075 0.093 0.057 0.494 0.299 2.22 1984 0.173 0.226 0.2 0.12 0.139 0.136 0.002 0.001 0.039 0.089 0.473 0.322 1.92 1985 0.028 0.142 0.123 0.038 0.02 0.115 0. 0.012 0.077 0.277 0.258 0.101 1.19 1986 0.446 0.272 0.094 0.045 0.06 0.014 0.039 0. 0.071 0.187 0.397 0.217 1.84 1987 0.345 0.108 0.331 0.125 0.109 0. 0.004 0.006 0.035 0.008 0.148 0.366 1.58 1988 0.22 0.022 0.194 0.167 0.133 0.07 0.014 0.006 0.077 0.113 0.505 0.199 1.72 1989 0.149 0.208 0.312 0.151 0.117 0.032 0.015 0.026 0.009 0.144 0.309 0.263 1.74 1990 0.491 0.23 0.123 0.098 0.059 0.124 0.022 0.015 0. 0.282 0.492 0.218 2.16 1991 0.263 0.26 0.26 0.266 0.04 0.044 0.012 0.11 0. 0.056 0.314 0.189 1.82 1992 0.462 0.181 0.079 0.167 0. 0.052 0.028 0.028 0.035 0.089 0.296 0.223 1.64 1993 0.212 0.014 0.28 0.288 0.138 0.116 0.028 0. 0. 0.068 0.09 0.272 1.51 1994 0.141 0.269 0.168 0.1 0.036 0.041 0. 0.009 0.054 0.166 0.311 0.481 1.78 1995 0.266 0.264 0.222 0.081 0.027 0.051 0.053 0.068 0.021 0.185 0.543 0.395 2.18 1996 0.424 0.461 0.119 0.302 0.063 0.028 0.011 0.06 0.049 0.244 0.233 0.479 2.47 1997 0.399 0.097 0.474 0.216 0.057 0.053 0.013 0.032 0.136 0.306 0.251 0.161 2.19 ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:04:12 AM Page 22 1998 0.522 0.203 0.235 0.038 0.079 0.039 0. 0.007 0.023 0.162 0.604 0.523 2.44 1999 0.435 0.44 0.189 0.038 0.063 0.043 0.048 0.016 0. 0.106 0.581 0.284 2.24 2000 0.206 0.308 0.137 0.043 0.111 0.063 0. 0.009 0.027 0.137 0.168 0.128 1.34 2001 0.137 0.106 0.118 0.14 0.05 0.111 0.033 0.095 0.03 0.14 0.472 0.333 1.77 2002 0.392 0.247 0.151 0.239 0.011 0.068 0.028 0. 0.003 0.02 0.197 0.34 1.69 2003 0.497 0.092 0.341 0.103 0.029 0.007 0. 0.002 0.01 0.333 0.339 0.223 1.98 2004 0.35 0.134 0.083 0.005 0.11 0.008 0. 0.119 0.095 0.144 0.158 0.253 1.46 2005 0.189 0.043 0.184 0.18 0.144 0.05 0.039 0.006 0.025 0.115 0.309 0.398 1.68 2006 0.697 0.146 0.08 0.121 0.048 0.073 0. 0. 0.052 0.067 0.794 0.401 2.48 2007 0.295 0.187 0.228 0.004 0.054 0.035 0.052 0.021 0.133 0.171 0.191 0.415 1.79 2008 0.25 0.076 0.179 0.047 0.02 0.065 0.008 0.116 0.026 0.089 0.316 0.239 1.43 2009 0.269 0.074 0.196 0.157 0.18 0. 0. 0.037 0.053 .97 ---PAGE BREAK--- RECHRES Elements POC Number: 1 Volume: Acre Feet Year Predeveloped Mitigated Pass/Fail 1948 0.2852 0.8111 Pass 1949 0.6762 1.5868 Pass 1950 1.4367 2.9061 Pass 1951 1.0257 2.1343 Pass 1952 0.4526 1.1300 Pass 1953 1.1810 2.6469 Pass 1954 1.0014 2.1447 Pass 1955 1.1401 2.3677 Pass 1956 0.9004 1.9626 Pass 1957 0.7610 1.7702 Pass 1958 1.0218 2.2270 Pass 1959 1.1574 2.3750 Pass 1960 0.9302 1.9807 Pass 1961 1.0757 2.3168 Pass 1962 0.7835 1.8110 Pass 1963 0.9326 2.0559 Pass 1964 1.0484 2.2092 Pass 1965 0.7842 1.7970 Pass 1966 0.8969 2.0390 Pass 1967 0.8304 1.8398 Pass 1968 1.2903 2.7243 Pass 1969 0.8015 1.8215 Pass 1970 0.8581 2.0080 Pass 1971 1.0621 2.2995 Pass 1972 1.2790 2.5893 Pass 1973 0.7928 1.8448 Pass 1974 0.9569 2.0779 Pass 1975 1.1004 2.3843 Pass 1976 0.6071 1.3302 Pass 1977 0.6427 1.5981 Pass 1978 0.7545 1.6647 Pass 1979 0.6990 1.6356 Pass 1980 0.8448 1.8912 Pass 1981 0.8171 1.7333 Pass 1982 0.9538 2.0957 Pass 1983 1.0100 2.2190 Pass 1984 0.8363 1.9219 Pass 1985 0.4686 1.1921 Pass 1986 0.8681 1.8427 Pass 1987 0.7104 1.5835 Pass 1988 0.6879 1.7208 Pass 1989 0.7368 1.7363 Pass 1990 1.0645 2.1565 Pass 1991 0.8607 1.8151 Pass 1992 0.6721 1.6386 Pass 1993 0.6443 1.5057 Pass 1994 0.7270 1.7754 Pass 1995 0.9984 2.1758 Pass 1996 1.3236 2.4730 Pass 1997 1.0854 2.1943 Pass 1998 1.1491 2.4355 Pass 1999 1.0471 2.2446 Pass 2000 0.5814 1.3354 Pass 2001 0.7734 1.7677 Pass 2002 0.7416 1.6945 Pass 2003 0.9301 1.9760 Pass 2004 0.6408 1.4601 Pass 2005 0.7329 1.6814 Pass 2006 1.2300 2.4772 Pass 2007 0.9113 1.7854 Pass 2008 0.6260 1.4291 Pass 2009 0.4671 0.9663 Pass Average Annual Recharge for POC: 1 Acre-Feet Predeveloped: 0.89 Mitigated: 1.95 Pass/Fail: Passed ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:04:25 AM Page 26 Appendix Predeveloped Schematic ---PAGE BREAK--- 2015-1110_infiltration 11/10/2015 11:04:26 AM Page 27 Mitigated Schematic ---PAGE BREAK--- 11 Chapter 2—Modifications to the 2005 DOE Stormwater Management Manual for Western WA ---PAGE BREAK--- 12 Chapter 2—Modifications to the 2005 DOE Stormwater Management Manual for Western WA ---PAGE BREAK--- Hydrologic Soil Group—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 6/11/2015 Page 1 of 4 5280750 5280780 5280810 5280840 5280870 5280900 5280930 5280960 5280990 5280750 5280780 5280810 5280840 5280870 5280900 5280930 5280960 5280990 565670 565700 565730 565760 565790 565820 565850 565670 565700 565730 565760 565790 565820 565850 47° 40' 44'' N 122° 7' 30'' W 47° 40' 44'' N 122° 7' 21'' W 47° 40' 36'' N 122° 7' 30'' W 47° 40' 36'' N 122° 7' 21'' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 50 100 200 300 Feet 0 15 30 60 90 Meters Map Scale: 1:1,280 if printed on A portrait (8.5" x 11") sheet. ---PAGE BREAK--- MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 10, Sep 30, 2014 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 31, 2013—Oct 6, 2013 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Hydrologic Soil Group—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 6/11/2015 Page 2 of 4 ---PAGE BREAK--- Hydrologic Soil Group Hydrologic Soil Group— Summary by Map Unit — King County Area, Washington (WA633) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI EvB Everett gravelly sandy loam, 0 to 5 percent slopes A 8.5 100.0% Totals for Area of Interest 8.5 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Hydrologic Soil Group—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 6/11/2015 Page 3 of 4 ---PAGE BREAK--- Tie-break Rule: Higher Hydrologic Soil Group—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 6/11/2015 Page 4 of 4 ---PAGE BREAK--- PROJECT SITE 42" SD 54" SD SAMMAMISH RIVER Redmond City Center Conveyance Map 85th St FILTER VAULT ---PAGE BREAK--- Earth Solutions Earth Solutions NW LLC Geotechnical Engineering Geology Environmental Scientists Construction Monitoring 1805 - 136th Place N.E., Suite 201 Bellevue, WA 98005 (425) 449-4704 Fax (425) 449-4711 www.earthsolutionsnw.com GEOTECHNICAL ENGINEERING STUDY & CRITICAL AQUIFER RECHARGE AREAS REPORT REDMOND CITY CENTER 16135 NORTHEAST 85TH STREET REDMOND, WASHINGTON ES-3191 2005 2015 ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- Be aware that the City has a published policy on temporary shoring soil nails extending into the right-of-way. ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- Drwn. Checked Date Date Proj. No. Plate Earth Solutions Geotechnical Engineering, Construction Monitoring Earth Solutions Earth Solutions NW LLC and Environmental Sciences Vicinity Map Redmond City Center Redmond, Washington MRS KDH 07/17/2015 July 2015 3191 1 NORTH NOTE: This plate may contain areas of color. ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black & white reproductions of this plate. Reference: Redmond, Washington Map 537 By The Thomas Guide Rand McNally 32nd Edition SITE ---PAGE BREAK--- Drwn. Checked Date Date Proj. No. Plate Earth Solutions Geotechnical Engineering, Construction Monitoring Earth Solutions Earth Solutions NW LLC and Environmental Sciences NORTH NOT - TO - SCALE LEGEND Approximate Location of ESNW Boring, Proj. No. ES-3191, June 2015 Subject Site Existing Building NOTE: This plate may contain areas of color. ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black & white reproductions of this plate. NOTE: The graphics shown on this plate are not intended for design purposes or precise scale measurements, but only to illustrate the approximate test locations relative to the approximate locations of existing and / or proposed site features. The information illustrated is largely based on data provided by the client at the time of our study. ESNW cannot be responsible for subsequent design changes or interpretation of the data by others. Boring Location Plan Redmond City Center Redmond, Washington MRS KDH 07/17/2015 July 2015 3191 2 Parking Lot Parking Lot B-1 B-2 B-3 B-4 B-1 Disused Post Office King County Transit Center N.E. 85TH STREET ---PAGE BREAK--- Drwn. Checked Date Date Proj. No. Plate Earth Solutions Geotechnical Engineering, Construction Monitoring Earth Solutions Earth Solutions NW LLC and Environmental Sciences CANTILEVER & SINGLE TIEBACK WALL D = Pile Embedment (per Structural Eng.) 2' H (Wall Height) Active Earth Pressure Passive Earth Pressure EFP = 300 pcf EFP = 35 pcf Surcharge (Where Applicable) Traffic Surcharge or Building Surcharge (Where Applicable) Excavation Level SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING NOTES: This Plate is intended for illustration of pressure distribution and is not a design drawing. The Passive Pressure value includes a factor-of-safety of 1.5. See text for adjacent building or traffic surcharges. Active Earth Pressure values shown on this plate are representative of drained conditions. See text for other construction conditions. NOTE: See text for recommended Slope Backfill and At-Rest Pressures. Neglect Upper 2 feet of Passive Pressure MRS 07/17/2015 3191 KDH July 2015 3 1. 2. 3. 4. Redmond City Center Redmond, Washington ---PAGE BREAK--- Drwn. Checked Date Date Proj. No. Plate Earth Solutions Geotechnical Engineering, Construction Monitoring Earth Solutions Earth Solutions NW LLC and Environmental Sciences NO LOAD ZONE D = Pile Embedment (per Structural Eng.) H (Wall Height) Traffic Surcharge or Building Surcharge (Where Applicable) Excavation Level SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING H/4 60 Tieback No Load Zone MRS KDH 07/17/2015 July 2015 3191 4 Redmond City Center Redmond, Washington ---PAGE BREAK--- Drwn. Checked Date Date Proj. No. Plate Earth Solutions Geotechnical Engineering, Construction Monitoring and Environmental Sciences Earth Solutions Earth Solutions NW LLC FOOTING DRAIN DETAIL Slope Perforated Rigid Drain Pipe (Surround with 1" Rock) 18" (Min.) NOTES: Do NOT tie roof downspouts to Footing Drain. Surface Seal to consist of 12" of less permeable, suitable soil. Slope away from building. LEGEND: Surface Seal; native soil or other low permeability material. 1" Drain Rock SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING Redmond City Center Redmond, Washington MRS KDH 07/20/2015 July 2015 3191 5 ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- 5+6' 2.#0 24'2#4'&(14 %15/15&'8'.12/'06 0 1 6 ) 5 6 # 6 # 6 9 ( 1 ' 0 + * 5 ' 4 ' & 4 ' ) + 5 0 20 20 10 APPROVED FOR CONSTRUCTION Plan Chk Storm For: Linda De Boldt Director of Public Works City of Redmond Fire Date: Trans / Planning This approval is for the design concept only. These plans appear to be in conformance with the City Of Redmond design standards for construction. This approval shall not be construed as authorizing construction not in accordance with applicable City standards. The City reserves the right to require revisions to the approved plans to assure conformance with City of Redmond design standards for construction at any time that it is discovered that the proposed construction does not otherwise meet the applicable construction standards. The owner is required to provide designs and plans in accordance with applicable City standards and assures that construction is accomplished in accordance with those standards. The owner and/or design engineer and/or dev eloper may be required to make necessary approved field revisions to correct any errors or omissions found on the approved plan. ---PAGE BREAK--- 76+.+6; 2.#0 24'2#4'&(14 %15/15&'8'.12/'06 0 1 6 ) 5 6 # 6 # 6 9 ( 1 ' 0 + * 5 ' 4 ' & 4 ' ) + 5 0 20 20 10 APPROVED FOR CONSTRUCTION Plan Chk Storm For: Linda De Boldt Director of Public Works City of Redmond Fire Date: Trans / Planning This approval is for the design concept only. These plans appear to be in conformance with the City Of Redmond design standards for construction. This approval shall not be construed as authorizing construction not in accordance with applicable City standards. The City reserves the right to require revisions to the approved plans to assure conformance with City of Redmond design standards for construction at any time that it is discovered that the proposed construction does not otherwise meet the applicable construction standards. The owner is required to provide designs and plans in accordance with applicable City standards and assures that construction is accomplished in accordance with those standards. The owner and/or design engineer and/or dev eloper may be required to make necessary approved field revisions to correct any errors or omissions found on the approved plan. ---PAGE BREAK--- Meadow Park Lake Sammamish Sammamish River Farrel-McWhirter Park Juel Community Park Hartman Community Park Perrigo Community Park Town Center Open Space Grass Lawn Community Park Municipal Campus Sammamish Valley Community Park Arthur Johnson Park Idylwood Beach Park Bear Creek Park Nike Neighborhood Park Viewpoint Conrad Olson Farm Westside Neighborhood Park Anderson Park Redmond West Wetlands Viewpoint Neighborhood Park Northeast Redmond Neighborhood Park Reservoir Park SE Redmond Neighborhood Park Luke McRedmond Landing Spiritbrook Neighborhood Park Marymoor Park Cascade View Neighborhood Park 148th AVE NE REDMOND WY WILLOWS RD BEL-RED RD NE 40th ST W LK SAMMAMISH PKWY RED-WOOD RD NE 124th ST 166th AVE NE 156th AVE NE AVONDALE RD NE 104th ST NE 51st ST UNION HILL RD 140th AVE NE NE 90th ST OLD REDMOND RD NE 116th ST 160th AVE NE 150th AVE NE NE 76th ST 171st AVE NE NE 85th ST 185th AVE NE 154th AVE NE NE 80th ST 152nd AVE NE 188th AVE NE NE 83rd ST LEARY WY NE 24th ST E LK SAMMAMISH PKWY AVONDALE WY 154th PL NE BEAR CREEK PKWY 161st AVE NE NE 36th ST CLEVELAND ST NE 79th ST NE 111th ST NE 124th WY 180th AVE NE 162nd AVE NE NE 20th ST 178th PL NE NE 100th ST 172nd AVE NE 170th AVE NE NE 109th ST 159th PL NE NE 110th ST NE 31st ST NOVELTY HILL RD 170th PL NE NE 116th ST NE 80th ST NE 85th ST NE 24th ST 180th AVE NE 172nd AVE NE Legend: Wellhead Protection Zone 1 Wellhead Protection Zone 2 Wellhead Protection Zone 3 Wellhead Protection Zone 4 Redmond City Limits 0 800 1,600 2,400 400 Feet" Critical Areas Map Effective: April 16, 2011 Map 64.6 Wellhead Protection Zones Note: This map shall be used as a general guide. It represents approximate locations. Consult the Critical Areas Ordinance (CAO) for reporting requirements. In the event there is a conflict between the map and the criteria or standards of the CAO, the criteria shall prevail. Sources: City of Redmond Public Works Department City of Redmond G:\Planning\COMPLAN & DEV GUIDE GRAPHICS\ArcGISMaps\RCDG Rewrite\GIS\FinalDrafts\Map64_6_RZC.mxd Site Location (Appx.) Within Wellhead Protection Zone 1 ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK---