Thirty Percent Design for Laxson South Bioretention Project

Transcription

1 TECNICAL MEMORANDUM DATE: July, 0 Project No.: SENT VIA: TO: Angela Spain FROM: Natalie Muradian, PE, RCE # REVIEWED BY: Doug Moore, PE, RCE # SUBJECT: Thirty Percent Design for Laxson South Bioretention Project INTRODUCTION The purpose of this Technical Memorandum (TM) is to provide the following information for the 0% design for the SWRP Project Laxson South Bioretention Project: Project Description Bioretention Basin Sizing Cost Estimate A Thirty Percent Design (Attachment A) Planting Palette (Attachment B) PROJECT DESCRIPTION The Laxson South Bioretention Project (Project) includes the installation of a bioretention basin on the California State University of Chico (CSUC) campus in an existing open space in front of Laxson Auditorium, north of the roundabout, at the intersection of Salem Street and st Street. The purpose of the Project is to: Reduce flooding that occurs in the roundabout and adjacent walkway during large storms. Reduce pollutants from first flush storms and low flows through infiltration and bioremediation. Recharge the underlying groundwater using storm water runoff. 00 Research Park Drive, Suite 00 Davis, CA Phone 0-0 Fax 0 - westyost.com

2 Technical Memorandum July, 0 Page The Project location and elements are shown in a draft plan set in Attachment A. The Project was sited based on the following factors and constraints: The grassy area between the roundabout and Laxson Auditorium is currently unused open space (Project site) and there are no plans for future improvements within the Project site. The Project site is adjacent to the roundabout, which will facilitate collecting the drainage from the roundabout without significantly impacting surrounding infrastructure. Underground utilities are located within the Project site boundaries. The Project is located to avoid and limit impact to these utilities. owever, locations and elevations of utilities have been estimated, and therefore, need to be confirmed. An old eucalyptus tree in the middle of the Project site will need to be removed; however, this tree will need to be removed within several years due to its age and condition. Accordingly, the Project includes mitigation with the planting of a new tree. Options for native California trees that can be planted near the bioretention basin are listed in Table of Attachment B. The Project includes the following elements: Three concrete channels convey flow under the existing sidewalk from the roundabout into the bioretention basin. Installing concrete channels will include reconstructing the curb and gutter around the channel inlet. The concrete channels will be covered with a decorative grate for the width of the sidewalk to allow runoff from the sidewalk to enter the channels. The grate will be rated for pedestrian and vehicle loads. The grassy area will be excavated approximately to a depth of.0 feet to capture and store the runoff from the tributary watershed (sizing information is discussed below). The bioretention basin will be vegetated with California native plants to provide water quality treatment. Table in Attachment B lists plants that will be used in the bioretention basin. A drain inlet set just below the gutter elevation will be installed in the bioretention basin to allow high flows to spill into the storm drainage system. An -inch storm drain is proposed for the connection to the existing storm drain in the roundabout. A new storm drain manhole will be installed at the connection point. This new storm drain manhole can also be used to take water quality samples. n\c\\0--0\wp\\0_laxon South TM

3 Technical Memorandum July, 0 Page BIORETENTION BASIN SIZIN The tributary watershed was estimated for the Project. The tributary watershed is approximately. acres and is shown on sheet C0 of the plan set in Attachment A. The drainage system for the roundabout is a 0-inch pipe, according to the City s IS database. Based on Chico s storm drainage standards, a storm drain system with pipes less than inches in diameter should be sized using a -year storm, therefore, a -year storm was used to estimate the volume of runoff that will cause flooding. A total depth of 0. inches of rainfall for a -year, -hour storm was selected, assuming that flooding occurs during the peak hour of a storm. The curb cuts are inches above the bottom of the gutter so only peak flows enter the basin. Based on the acreage of the tributary watershed, approximately 0.0 acre-feet of rainfall will occur in a -year, -hour storm. It was assumed that all 0.0 acre-feet of rainfall will turn into runoff, assuming that the -hour storm is not an isolated event and initial losses would be minimal. Based on this estimate, a volume of at least 0.0 acre-feet was selected for basin storage. The space constraints for the bioretention basin results in a depth of approximately.0 feet and :V side slopes to achieve an approximate storage volume of 0.0 acre-feet. COST ESTIMATE The capital cost for the Project is approximately $0,000, see Table. The annual operations and maintenance (O&M) cost includes hours for cleaning the basin per quarter, an hour of administration associated with maintenance and sampling, and water quality testing of the runoff once per quarter. The annual O&M cost is approximately $,000, see Table. If professors or students volunteer to collect and analyze samples, the cost of O&M could be reduced by approximately $,00. DISCLAIMER Funding has been provided in full or in part through an agreement with the State Water Resources Control Board, using funds from Proposition. The contents of this document do not necessarily reflect the views and policies of the foregoing, nor does the mention of trade names or commercial products constitute endorsement or recommendation for use. This work product is part of Task.0 of rant Agreement No. D between the City of Chico and the California State Water Resource Control Board. Accessed from the National Oceanic Atmospheric Administration s (NOAA) Precipitation Frequency Data Server. n\c\\0--0\wp\\0_laxon South TM

4 Table. Cost Estimate for SWRP Project - Laxson South Bioswale Number Bid Item Units Quantity Unit Price, dollars Total Price, dollars Bioretention Basin Trench Drain EA,000,000 New manhole EA,000,000 Drain Inlet EA,000,000 " Storm Drain Line LF 0 00 Excavation, Off aul, & rading CY 0,00 Bioretention Soil (" Depth) CY 00 0,000 Wood Mulch (Matting Variety " Depth) CY 0,00 Drain Rock CY Vegetation - allon Pots EA 00 0 Vegetation - " Pots EA 0,00 Sample Area EA,00,000 Signage LS Subtotal (Rounded) $,00 eneral Construction Mobilization/Demobilization & Insurance (%) LS --,00 Construction Contingency (0%) LS --,000 Construction Costs $,00 Engineering and Design Fees Engineering, Administration, Permitting (%) LS --,0 Total Estimated Capital Project Cost (Rounded) $0,000 Table. Cost Estimate for Annual O&M for SWRP Project - Laxson South Bioswale Item No Item Description Units Quantity Unit Cost, dollars Total Cost, dollars Person Maintenance Crew and Equipment, hours per quarter R,00 Administration R 0 0 Sample (Lab Cost, once per quarter) EA,000,000 Total Estimated Project Cost (Rounded) $,000 n\c\\0--0\wp\\0_laxon South TM Last Revised: 0-- City of Chico SWRP Project 0 0% Design - Laxson South Bioretention

5 ATTACMENT A Plan Set

6 A B C D E F I J K L M N O P 0 0 Location CSU CICO Vicinity BI CICO CREEK AND LITTLE CICO CREEK STORM WATER RESOURCES PLAN LAXSON SOUT BIORETENTION W st ST SALEM ST PROJECT AUUST 0 W nd ST 0 Microsoft Corporati LOCATION MAP VICINITY MAP DRAWIN INDEX SEET NO. DRAWIN NO. DESCRIPTION 00 Koll Center Parkway Suite 0 Pleasanton, CA () -0 FAX (0) - BI CICO CREEK AND LITTLE CICO CREEK STORM WATER RESOURCE PLAN 0% DESIN 0 TITLE SEET, LOCATION & VICINITY MAPS, AND DRAWIN INDEX A B C D E F I J K L M N O P

7 A B C D E F I J K L M N O P 0 0 ST ST SALEM ST LAXSON SOUT BIORETENTION BASIN PROJECT VICINITY LAXSON SOUT BIORETENTION BASIN PROJECT 00 Koll Center Parkway Suite 0 Pleasanton, CA () -0 FAX (0) - BI CICO CREEK AND LITTLE CICO CREEK STORM WATER RESOURCE PLAN 0% DESIN C0 PLAN VIEW OF LAXSON SOUT BIORETENTION BASIN A B C D E F I J K L M N O P

8 A B C D E F I J K L M N O P 0 0 DETAIL DETAIL SECTION SECTION 00 Koll Center Parkway Suite 0 Pleasanton, CA () -0 FAX (0) - BI CICO CREEK AND LITTLE CICO CREEK STORM WATER RESOURCE PLAN 0% DESIN C0 LAXSON SOUT BIOSWALE DETAILS AND SECTIONS A B C D E F I J K L M N O P

9 A B C D E F I J K L M N O P 0 0 SECTION DETAIL 00 Koll Center Parkway Suite 0 Pleasanton, CA () -0 FAX (0) - BI CICO CREEK AND LITTLE CICO CREEK STORM WATER RESOURCE PLAN 0% DESIN C0 DETAILS AND SECTIONS A B C D E F I J K L M N O P

10 ATTACMENT B Planting Palette

11 Chico SWRP Plant Lists Prepared by Foothill Associates Table Native Trees for Edge of Bioretention Basins Scientific Name Common Name Mature Size (xw in feet) igh Bank or Low Bank Acer macrophyllum Big leaf maple 0x0 L Acer negundo californica California box elder 0x0 L Aesculus californica California buckeye 0x Alnus rhombifolia White Alder 0x0 L Cercis occidentalis Western redbud x Fraxinus latifolia Oregon ash 0x0 L Platanus racemosa Sycamore 0x0 L Populus fremontii Cottonwood 0x0 L Quercus douglasii Blue oak 0x0 Quercus lobata Valley Oak 0x0 Quercus wislizeni Interior Live oak 0x0 Umbellularia californica California laurel 0x0 L Tree Planting Notes:. igh Bank/Low Bank refers to the preferred location of said tree. Low bank trees should be planted within feet vertically of the basin floor. igh bank trees should be planted more than feet from basin floor. Those trees which prefer low banks typically require more water and more consistent water. Those which prefer high banks are typically more drought tolerant.. It is recommended that trees be planted between October and December, after first significant rain event, to allow initial establishment during winter wet season.. Temporary irrigation is required during summer dry season for three years and recommended for five to ensure plant establishment.

12 Table Bioretention Basin Channel Bottom Seed Mix Scientific Name Common Name County of Seed Origin Pounds of Live Seed Per Acre Carex barbarae Santa Barbara sedge Plugs Yolo Bypass, Yolo Co. O.C. Carex praegracilis cluster field sedge Tiburon, Marin Co. O.C. Elymus glaucus blue wildrye Yolo Bypass, Yolo Co. Elymus triticoides creeping wildrye Yolo Bypass, Yolo Co. ordeum brachyantherum meadow barley Yolo Bypass, Yolo Co. Juncus effusus common rush Placer Co. O.C. Juncus patens grey rush Cache Creek Watershed, Yolo Co. O.C. Total: 0 Channel Basin Planting Notes:. Plugs are recommended for those plants which typically propagate vegetatively in the wild. The success of plugs is significantly higher than seed as seeds can be very difficult to germinate in natural conditions and seeds can be prohibitively expensive to acquire.. It is recommended that seeding and planting be performed between October and December, after first significant rain event, to allow establishment during winter wet season.. Seeds and plugs can be acquired through hedgerow farms. Contact: 0 County Road Winters, CA 0

13 Table rasses and Plants for Channel Banks Scientific Name Common Name County of Seed Origin Pounds of Live Seed/Acre Achillea millefolium yarrow Cache Creek Watershed, Lake Co. Artemisia douglasiana mugwort West Sacramento, Yolo Co. 0. Bromus carinatus California brome Arastradero Preserve, Santa Clara Co. Clarkia unguiculata elegant clarkia Rumsey Canyon, Yolo Co. 0. Elymus glaucus blue wildrye Llano Seco Ranch, Butte Co. Elymus triticoides creeping wildrye Yolo Bypass, Yolo Co. Eschscholzia californica California poppy Lodoga ills, Colusa Co. 0. Festuca microstachys three weeks fescue Vina Plains Preserve, Tehama Co. rindelia camporum gum plant Yolo Bypass, Yolo Co. ordeum brachyantherum meadow barley Yolo Bypass, Yolo Co. ordeum brachyantherum ssp. californicum California barley wy 0, Colusa Co. Layia platyglossa tidy tips Bear Valley Road, Colusa Co. Lupinus microcarpus var. densiflorus golden lupine North of Winters, Yolo Co. Lupinus succulentus arroyo lupine North of Winters, Yolo Co. Nemophilia menziesii baby blue eyes Commercial Stipa pulchra purple needlegrass Llano Seco Ranch, Butte Co. Trifolium willdenovii tomcat clover North of Winters, Yolo Co Total: Channel Bank Planting Notes:. It is recommended that seeding be performed between October and December, after first significant rain event, to allow establishment during winter wet season.. Seeds can be acquired through hedgerow farms. Contact: 0 County Road Winters, CA