11-17-99 vl 1
MINUTES OF ATLANTIC BEACH CITY COMMISSION PUBLIC HEARING ON THE
STORMWATER IMPROVEMENTS PROJECT HELD AT THE ATLANTIC BEACH
ELEMENTARY SCHOOL AT 6:00 P.M. ON WEDNESDAY, NOVEMBER 17, 1999
Commission Members present were Mayor Meserve and Commissioners Beaver, Borno and
Waters.
Staff Members present were City Manager Jim Hanson, Public Works Director Bob Kosoy,
Assistant Public Works Director Donna Kaluzniak, and City Clerk Maureen King.
Mayor Meserve called the meeting to order and provided a brief history of the stormwater
improvements project which included comments on the CH2M Hill Stormwater Master Plan,
the design work of England, Thims and Miller, the rejected preliminary design work of
The R-A-M Group and the preliminary findings of the current engineering firm of Aikenhead
and Odom (A & 0).
Mayor Meserve deferred to City Manager Hanson for a financial update on the project. Using a
flip chart, City Manager Hanson briefly explained the amount of the original utility bond
construction fund, the amount of that money which had been expended or committed to date,
and the amount of money that remained in the budget for the project. A summary of the
financial information presented is attached and made part of this official record as Attachment
A. City Manager Hanson stated that television inspection of the sewer lines revealed
infiltration equivalent to 400,000 gallons per day from cracks in the lines. He indicated that the
city planned to use "trenchless technology" by slip lining existing sewer lines and indicated that
the sewer lines would be smoke tested for leaks and improper connections in the near future.
Neil Aikenhead, President of Aikenhead and Odom, provided an overview of the project using a
Powerpoint presentation. Mr. Aikenhead indicated that the firm had modified the design
prepared by England, Thims and Miller (ETM) and developed a concept for improving the core
city and entire Selva Lagoon drainage systems to handle a multi-event storm with big flood
conditions, which would allow the city to operate with relatively normal drainage conditions.
Mr. Aikenhead reported there was a natural fall to the drainage system with elevations of 9.0 at
City Hall, 8.0 at A-1-A and 7.0 at Wonderwood. He proposed a street-by-street design solution
for each existing system based on all survey, geotechnical and related design information
available. He indicated that there would be individual stub outs for private drains and no curb
and gutter was being proposed. He felt this would afford substantial construction dollar savings
to the city, as well as minimize the impacts to existing trees and landscaping and provide a
consistent look. Mr. Aikenhead also proposed some low flow pumps near Water Plan#2 and a
flap gate at the western entrance to Fleet Landing.
Mr. Aikenhead stated that while considerable work had been completed during the preliminary
design work, there was still much to be done. He recommended that project be completed in
two phases with costs ranging from $4-6 million for Phase I construction and $2-5 million for
Phase II, which included the cost of high flow pumps to pump the water through the Selva
Marina golf course. He indicated that the cost would vary depending on the size of the pumps
Stormwater Improvements Project Public Hearing
1110 Page -2-
November 17, 1999
installed at the golf course. Mr. Aikenhead felt that it was critical to permit the entire project,
even if it was completed in phases.
Following the presentation, Mr. Aikenhead responded to questions and comments from the
following citizens:
Tom Trechel of 312 9th Street inquired as to when the design for the project would be
completed. Mr. Aikenhead responded that it would take three to four months to complete
modeling for the project and approximately six months to design and permit the project. He felt
it would be one year before actual construction on the project would begin.
Barbara Hopson of 760 Sherry Drive believed Howell Park should be saved at all costs. She
believed it should remain lush and green with trees. Ms. Hopson stated she did not want to lose
the flavor of the core city area.
Harold Brodeur of 1965 Sevilla Boulevard, President of the Sevilla Gardens Homeowners
Association, felt the wetlands near Fleet Landing were already overtaxed and requested
assurance that too much water would not be deposited downstream.
Betty Eilers of 369 Third Street stated that her house had been flooded five times and she had
spent thousands of dollars to keep the water out of her home. Mrs. Eilers believed that part of
the flooding problem was caused by the twelve inch thick pavement in front of her home which
allowed the water to flow into her yard. Mrs. Eilers also reported that raw sewage still came out
of a manhole by her home. She felt correcting this problem should be a number one priority for
the city.
Richard Devane of 386 4th Street stated that existing storm drains were often filled with trash
and not defined. He favored the use of a drop curb and stated he wanted consideration of some
type of curb and gutter.
Leslie Frye of 336 2" Street stated that his home was built in the 1950's and at that time the
area where the Atlantic Beach Elementary School now exists was a swamp, which was filled in
by the WPA in about 1948. Mr. Frye favored pumping the water from the core city area and felt
that curb, gutter and sidewalk were not necessary.
Ray Brady of 1636 Sea Oats inquired as to what was proposed for Howell and Johansen Parks,
and who the tree consultant would be for the project. He felt that narrowing some existing streets
and making them one-way would help alleviate the drainage problem. Mr. Aikenhead
responded that minimum drainage improvements would take place in Howell Park and would
include silt and cypress knee removal. Mr. Aikenhead stated that the park would be maintained
in its natural state, and stated that Early Piety would be retained as the arborist for the project..
Stormwater Improvements Project Public Hearing
Page -3-
November 17, 1999
Mr. Aikenhead indicated that little if anything would be done in Johansen Park. He also felt one-
way streets were a way to save dollars on the project.
Theresa Weatherford of 371 9th Street commented that she had suffered from flooding
problems for ten years and had lost three trees over the years due to the standing water in her
yard.
Sally Clemens of 1638 Park Terrace West felt the city should clean and then maintain all of its
drainage ditches and inquired if an evaluation of this problem would be undertaken before the
residents have to take measures to alleviated drainage problems in their own yards. Mr.
Aikenhead recognized sedimentation as a problem and stated that they would address the
siltation issue.
Steve Fouraker of 6`h Street stated that he was impressed with the presentation and was glad
that the firm of Aikenhead and Odom was working on a design he felt would protect the
citizens of Atlantic Beach. He believed it was acceptable to change the plan for Howell Park
with public input. He stated that he had been a resident of the area for fifty years and city had
always flooded in the area of the elementary school. Mr. Fouraker expressed opposition to
paying for solutions to problems of people who bought property which floods.
Carolyn Woods of 303 6`h Street commented that the water flowed from East Coast Drive
westward to Howell Park and she believed that the residents west of East Coast Drive should not
have to take all of the water. She further stated that her garage, which is below street level,
floods. Mrs. Woods commented that the properties closer to the ocean were the most
impervious and traffic calming should be considered.
Jeff Woods of 303 6`h Street concurred with his wife's statements.
Don Phillips of 1566 Park Terrace West supported the one way street suggestion. Mr. Phillips
stated that he had been involved with the core city project since 1995 when the CH2M Hill
Stormwater Master Plan was completed. He stated that city has not maintained it storm drains,and
pointed out that a drain was crushed on 9th Street and several others were silted in on 12`h Street.
He stated that England, Thims and Miller(ETM)had used an uncalibrated model and upsized the
diameter of pipe required by the Stormwater Master Plan from 36" to 54". Mr. Phillips
emphasized the importance of using calibrated models and commented that during the October 26,
1996 ten year storm,Joe Posch and he had checked the area and found the level to be at 61/2 feet on
Plaza, whereas, R-A-M had used 9 feet which resulted in an over design of the system and waste
of money. Mr.Phillips requested that the tidal influence on the system be considered and stated that
he would like to see more definitive information before authorizing a final design. He suggested a
phased contract with Aikenhead and Odom to include a model study.
III
Stormwater Improvements Project Public Hearing
Page -4-
November 17, 1999
Cam Brown of 1570 Park Terrace West thanked the Commission for revisiting this issue and
stated that as the Chairperson of the Save Johansen Park Committee,she favored hiring Early Piety
and opposed construction of a retention pond in Johansen Park.. She felt it was unfair to solve
other people's drainage problems by constructing a retention pond in her front yard,which she felt
would devalue her property. Mr. Aikenhead responded that there were no plans to do anything in
Johansen Park at this time.
Ann Meuse of 337 11th Street expressed concern about the proposed street by street design of the
project and stated that she had lived in the city since 1976 and the streets were in the worst condition
she had ever seen. Mrs. Meuse indicated that she had sat through numerous meetings and listened
to countless suggestions on how to solve the drainage problems without any resolution. She felt she
was part of the silent majority who were tired of all of the delays. She then inquired as to
Aikenhead and Odom's qualifications to bring all of the various factions together to get the job
done.
Mr. Aikenhead responded that the company was very computer literate, knew drainage well, and
had been in business for twenty years. He stated that the company was founded on the premise that
careful,detailed engineering would save substantial construction and long-term maintenance costs.
Dick Hilliard of 338 11th Street inquired concerning use of the existing gravity sewer line. Public
Works Director Kosoy responded that it could not be used since it is still in use as a by-pass line for
the sewer plant. Mr. Hilliard also suggested that the city clean its drains.
Alan Potter of 374 2" Street stated that he was encouraged by the report. He expressed concern
that no topographical survey or elevations were taken of the Selva Lagoon,the computer modeling
would be faulty. He also felt the city did not know the actual condition of its drainage system and
pointed out that there had been no maintenance of the system for forty-five years. Mr.Potter felt that
the preliminary report did not provide enough information and should include a priority list with the
dollar amounts in order for the city to know what it will get for the dollars being spent.
Stephen Kuti of 1132 Linkside Drive condemned the previous proposals of ETM and R-A-M as
being over designed. He felt the firm of Aikenhead and Odom was a good company with good
engineers. Mr. Kuti felt it was very important to control tidal waters and stated that if the city
purchased a tidal control gate for Wonderwood Road, the Jacksonville Transportation Authority
JTA)would install it. He felt that since the city was one year away from a final design for the core
city drainage system, the Commission should authorize the installation of the Wonderwood tidal
control gate and cleaning of the drainage ditches and Selva Marina Lagoon. He felt that the
immediate implementation of these items would eliminate the need for the high powered pumps
proposed by Aikenhead and Odom at the lagoon.
0 Cindy Corey of 394 8th Street hoped that the early recommendations of the Howell Park Review
Stormwater Improvements Project Public Hearing
0 Page -5-
November 17, 1999
Committee would be considered. She felt it was important to reduce impervious surface and
increase landscaping to correct drainage problems. She felt that innovative solutions, such as the
treatment train" should be followed. Ms. Corey expressed concern regarding where the water the
city proposed to pump would go, its impact on the area and if an agreement was needed since it
would be placed outside the city.
J.P. Marchioli of 414 Sherry Drive stated that the scope of work had been stipulated for the core
city in the original bond issue and he felt that the work being proposed was expensive, and outside
scope of work stipulated in the bond issue. Mr. Marchioli felt that some statements in the
preliminary report were erroneous and he read a prepared statement listing his recommendations
to save money and solve the city's drainage problems. Some of the recommendations included
installation of pipes and culverts on Sherry Drive,no one-way streets, installation of uniform curbs
citywide, and lowering the existing street levels.
Tom Burdette of 1193 Linkside Court inquired as to what was considered the core city area. Mr.
Aikenhead stated that the area ran from East Coast Drive to Sherry Drive on the west and from
Ahern Street to 14`h Street on the north. Mr. Burdette suggested that the city use curb and gutter,
mill the streets to grade, and remove the water in the core city area by pumping it to the Intracoastal
Waterway. He felt the Selva Lagoon problem could be resolved by running a dragline through the
lagoon to remove silt buildup.
Mr. Aikenhead stated he would take the suggestions into consideration.
Sylvia Simmons of 211 Beach Avenue read from a prepared statement and expressed concern
regarding the cost of curb and gutter, loss of trees in the core city area, the addition of impervious
surfaces, and any change to the existing narrow village streets and pedestrian friendly sidewalks
and lanes which reflect the traditional coastal-community town ambiance of Atlantic Beach. Mrs.
Simmons believed the city needed to keep the existing character of the area, with retaining the
existing tree canopy being a priority. A copy of the document Mrs. Simmons read is attached and
made part of this official record as Attachment B.
Mayor Meserve thanked the citizens for their input and stated that all comments and suggestions
would be taken into consideration..
The Mayor declared the public hearing closed at 8:47 p.m.
Julie M. Brandt
Secretary
1111
ATTACHMENT A
NOVEMBER 17, 1999 PUBLIC HEARING -
STORMWATER IMPROVEMENTS PROJECT
SUMMARY OF FINANCIAL INFORMATION
PROVIDED VIA FLIP CHARTS
AT THE STORMWATER PUBLIC HEARING OF MAY 17, 1999
ORIGINAL UTILITY BOND
CONSTRUCTION FUND - 1996
Water Distribution 2.01 m
Sewer Collection 4.29 m
Water/Sewer Plants 3.93 m
Stormwater 4.03 m
Subtotal 14.26 m
Refmancing (Ins., Int., Disc.) 8.58 m
TOTAL BOND FUND 22.84 m
MONIES SPENT OR COMMITTED TO DATE
Water Distribution 1.09 m
Sewer Collection 0.97 m
Water/Sewer Plants 4.63 m
Stormwater 1.81 m
Total Spent 8.50 m
REMAINING BOND FUNDS 5.76 m
REMAINING BUDGET
Water Distribution 1.15 m
Sewer Collection 1.09 m
Stormwater 6.92 m
TOTAL 9.16 m
FUNDING
Bond Balance 5.76 m
Reserves/Other 3.40 m
TOTAL 9.16 m
S
ATTACHMENT B
NOVEMBER 17, 1999 PUBLIC HEARING
STORMWATER IMPROVEMENTS PROJECT
October 15, 1998
CITY OF ATLANTIC BEACH
REQUEST FOR PROPOSALS
FOR PROFESSIONAL ENGINEERING SERVICES
NOTICE is hereby given that the City of Atlantic Beach, Florida, will receive proposals,
submitted in triplicate, at the Office of the Purchasing Agent, 1200 Sandpiper Lane, Atlantic
Beach, Florida 32233 until 4:30 p.m.,Wednesday, November 18, 1998, for:
a) PROFESSIONAL ENGINEERING SERVICES DESIGN MODIFICATION CORE CITY
UTILITY IMPROVEMENTS STORMWATER COLLECTION, and
b) PROFESSIONAL ENGINEERING SERVICES DESIGN OF TIDAL AND FLOOD-
CONTROL STRUCTURES FOR TAILWATER CONTROL.
Detailed Proposals can be obtained for 510.00 each from the Office of the Purchasing Agent by
contacting Ms. Joan LaVake at(904)247-5818. Questions regarding proposals shall be directed
to Mr. Robert S. Kosoy, P.E., Director of Public Works (904) 247-5834.
Proposals will a evaluated i tthe: ollbwing criteria:
1. Staff Competence (rating weight - 20%) -- include detailed resumes.
2. Similar Project Experience 7 t, ) -- a) Emphasis on creativity in finding solutions to
difficult stormwater management challenges to include familiarity with such
techniques as baffle boxes, sand traps, and swirl concentrators; and b) Emphasis on
creativity in finding solutions to difficult tidewater control challenges.
Documented',experience in retrofitting older.communitiesto providethe desired level
of service and meet current regulatory standards iv ring.teeir l cte will
be given the.;greatest credit.
3. References (10%) -- include telephone numbers.
4.tiAifrattAlfigMli ,%) -- include outline for accomplishing specific tasks along
with any recommended improvements and/or deviations in the time frame outlined
in the "Milestones/Deliverables" Section of the Request for Proposals.
5. Current Workload (5%) -- include firm and individual workloads.
6. Financial Information (5%) -- include last two years certified financial statements,
audit summary and current certificate of insurance.
The top firms will be required to make a formal presentation to the City Commission.
Revised 10/14/98
REQUEST FOR PROPOSALS (RFP)
PROFESSIONAL ENGINEERING SERVICES
DESIGN MODIFICATION
CORE CITY UTILITY IMPROVEMENTS
STORMWATER COLLECTION
FOR THE CITY OF ATLANTIC BEACH
I.PURPOSE: The City of Atlantic Beach, henceforth known as the City, is
soliciting for proposals from professional engineering firms to modify its current
design for a new stormwater collection system in the Core City, provide value
engineering on selected components of the design as specified, and assist the City
during the bidding phase for selecting a firm to construct the system.
II. BACKGROUND: In 1991, the Environmental Protection Agency (EPA)
mandated that the City develop a plan for stormwater management. In response
to this mandate, along with a growing outcry by citizens regarding an increased
frequency and magnitude of flooding, the City commissioned CH2M Hill to
develop a Stormwater Master Plan. Once the Stormwater Master Plan was
completed in 1995, the city contracted with England, Thims, & Miller, Inc. (ETM)
to, among other tasks, design a stormwater collection system for the Core City.
This work was completed in January of 1998. Subsequent to this, it became clear
that there was a strongnterest among.the citizens thatmore be doneto uphold the
character of the Core City,with emphasis on minimizing the impact of the project
on the environment and aesthetics of the community. In addition, many citizens
wanted more scrutiny on cost effectiveness. After a thorough review, on May 12,
1998 the City decided to modify the design to minimize the impact of construction
and operation on both Howell and Preben Johansen Parks and attempt to reduce
the cost of construction by performing value engineering on specific components
of the project. It is also important to note that the City decided to include
Upstream Management and Tailwater Control as two additional components of
an effective Stormwater Management Plan via additional, separate RFP's.'
The City agreed than an effective Stormwater Management Plan includes three components-
Upstream Management and Tailwater Control in addition to Stormwater Collection. The Commission
directed Staff to prepare RFP(s)to ensure that the Upstream Management and Tailwater Control were
adequately addressed and each component will have a separate RFP. The firm chosen to modify the
stormwater collection system must ensure coordination with these other two components.
RFP FOR STORMWATER COLLECTION DESIGN MODIFICATION (Continued):
III. SERVICES REQUESTED: In providing the following services, the selected firm
must place special emphasis on upholding the character of the Core City, with
emphasis on the environment and aesthetics, and ensuring cost effectiveness.
This character is defined as a pedestrian-friendly, environmentally "green" central
village in which the streets, parks, beachfront, and Town Center area form the
social hub of the community. Specific elements of the Core City to be preserved
are: (1) Existing narrow village streets and lanes which reflect the traditional
coastal-community town ambiance of Atlantic Beach', (2) Pedestrian friendly
sidewalks, paths, and streets of a recreational nature, which are currently heavily
used by residents of the City to walk or bicycle to their destinations, (3) Existing
tree canopy and native vegetation that currently provides both aesthetic and
environmental benefits to the City, (4) Existing parks and recreational areas, and
5) Areas of historical significance.
A. Assist the City in creating understanding and building consensus among its
citizens by working hand-in-hand with the City's Stormwater Review
Committee (SRC).3 The selected firm must, as a minimum, conduct public
30%, 60%, and 90% design reviews.
B. In order to avoid or, at least, minimize the impact to existing natural areas:
1. Provide plans, bill of materials (BOM), specifications, cost estimate, and
construction schedule for the replacement of the Howell Park stormwater
treatment component of the ETM design with upstream baffle boxes, sand
traps, swirl concentrators, holding basins, dry detention, or other concepts
that adequately accommodate design flows and meet the requirements of
stormwater treatment as necessary.' Included in this task is the re-
2Specifically, it has been concluded that the majority of the residents want to avoid altering the
existing Core City to that of the vehicular-friendly, artificially-landscaped,highly manicured, and other
typical characteristics of planned unit developments designed in the 1980's and 1990's.
3The Stormwater Review Committee(SRC)brings together the different interests and expertise
of the community to assist the City in planning for effective and efficient stormwater management.
4If, in the early stages of concept development,the St.Johns River Water Management District
agrees that improved upstream management of stormwater such as grassy swales, expanded
maintenance,appropriate ordinances,etc.can preclude or reduce the downstream treatment require-
ments,this approach must be brought to the attention of and should be seriously considered by the City.
2
RFP FOR STORMWATER COLLECTION DESIGN MODIFICATION (Continued):
engineering and redesign of the conveyance structures and entry points
into Selva Lagoon and/or Howell Park.
2. Provide plans, bill of materials, specifications, cost estimate and
schedule for the replacement of the Preben Johansen Park stormwater
treatment component of the ETM design with upstream baffle boxes, sand
traps, swirl concentrators, holding basins, dry retention or other concept that
adequately accommodate design flows and meet the requirements of
stormwater treatment as necessary.
3. Evaluate the existing treatment benefits of open, undeveloped and/or
preserved areas of park lands and other public lands, including but not
limited to Howell and Preben Johansen Park. Prepare a decision briefing
for City on the feasibility of leaving these areas undisturbed to provide
natural stormwater treatment and retain the present character of these areas.
C. Perform selective value engineering' with the goal of assuring the City realizes
a cost effective stormwater treatment collection system while not sacrificing
the permitability of any component. The firm is free to bring any ideas to the
City that it believes can result in significant savings while maintaining the
system effectiveness. Although not limiting, the firm will specifically address
the following-
1. Evaluate curb and gutter in the current ETM design including a cost and
benefit analysis, taking into account traffic considerations and other
roadway design alternatives.
2. Reducing the number of conflict manholes.
3. Preserving to the greatest extent practicable recently installed water mains
on 1st, 3rd, 8th, 9th and 11th streets as well as other water mains that are
serviceable and meet the requirements of the Department of Health.
4. Evaluate drainage pipe size requirements in the Core City to reflect any
benefits of tailwater and tide control design.
5. Increasing the capacity of the east-west streets to transport surface flows in
a way that increases the design flow for which the system provides
protection.
5In an effort to save money and time in the redesign process,selective value engineering implies
looking only at the project components specified. If there are clearly other modifications that will save
significant resources, they should be brought to the City for its consideration and approval before making
any changes.
3
RFP FOR STORMWATER COLLECTION DESIGN MODIFICATION (Continued):
D. With regard to trees, recommend design alternatives that maximize the
preservation of the existing natural vegetation and tree canopy of the Core City.
Specifically:
1. Evaluate the impact of the project on trees in andloutside of the project
right-of-way, to include the effects of loweringthe water table, root
removal, and other construction impacts.
2. Recommend ways todecrease the number of trees 'equiring removal.
3. Once evaluation is complete, recommend ways-to reduce the impact of the
project on trees_outside,ofhe•project•right-ofway and provide a mitigation
plan for any permanent and long-term damage (up to five years after project
completion) resulting from construction. If advisable, mitigation plan
should include vegetation replacement for those plants that will
experience long-term, irreparable harm.
4. Recommend controls on and techniques of construction that will serve to
protect all vegetation from the effects of the work.
E. Assess the feasibility and advisability of providing for underground utilities in
conjunction with this construction project, to include electrical, natural gas,
TV, and/or telephone lines/cables. If selected for inclusion by the City,
incorporate the component(s) into the design.
F. Collect field data (surveys, soil samples, etc.) to the extent necessary to
complete the tasks in paragraphs III. A., B., C., D., and E.
G. Prepare a complete set of plans, BOM, specifications, cost estimate, schedule,
and any other items which will be used to bid and construct the project by
incorporating the modifications requested above into the ETM plans and
supporting work products.
H. Support the City during the bidding phase of the Core City stormwater
collection project. Tasks include:
1. Prepare plans, bill of materials, specifications, etc. for the bidding phase to
be sold to the bidders through the City Purchasing Depaitment.
2. Assist City during pre-bid meeting to include providing technical
explanations and answering questions.
3. Prepare bid addenda as appropriate.
4. Evaluate all bids, prepare bid tabulation, and submit comments, as
appropriate.
4
I
F ,,.
0 V. Preservation of Core City Trees
I'f
1 __-_-k- A. Existing Tree Inventory
411ei. 'S
The existing vegetation in the Core City of Atlantic Beach creates the unique
streetscape character that is highly valued by the residents of the community. Along
portions of these narrow streets is a mix of mature overstory vegetation. This tree
canopy is visually pleasing and environmentally comfortable for pedestrian and
vehicular use. Each street has a variety of species including live oak, laurel oak,
sabal palm, southern red cedar, magnolia, maple, and hickory. Diversity of tree
species along these streets in the Core City neighborhood is depicted in Figure V.1.
Of particular interest is the sculptural qualities of larger live and laurel oak limbs and
leaf masses that extend over the roadways. These large trees filter sunlight and
provide a scale to the streets that is visually significant. Most of the larger varieties
of trees exist on private property adjacent to the right-of-way with spreading root
systems that extend under the street. These species, which are generally live oak,
laurel oak, and magnolia, are of primary concern in the planning of the R-A-M
Team's recommended drainage system.
Generally, the root zone for all existing trees is irregular in depth and area.
The National Arbor Foundation and American Forests have determined that 99% of
a tree's root system is located within the upper 36 inches of the soil structure and the
vital root area is found within the"dripline"of the tree. Plotting and measuring each
dripline in plan view can be determined by converting the Diameter at Breast Height
DBH) of the trunk in inches to a radial distance in feet away from the center of the
trunk. This radial measurement on the plan provides a baseline for determining the
extent of the root zone as illustrated in Figure V.2. Some roots of trees in the Core
City area may actually extend under the street beyond the far edge of pavement and
acquire a small portion of its water and nutrient consumption from that opposite side.
These canopy characteristics have been noted and evaluated for impacts.
Howell Park has been identified as a potential impact area for controlling
and filtering stormwater runoff. This passive recreation area contains tree species
typical of a Lowland Maritime Forest community as illustrated in Figure V.3. Mostly
all tree species located within the Howell Park area will tolerate flooding. However,
after further analysis of the drainage area, Howell Park will not be used for
stormwater control.
City of Atlantic Beach Page V-1 Preliminary Design Report
Core City Redesign/Tailwater Control March 15, 1999
1110
FIGURE V.1 IMPACT ON VEGETATION
CITY OF ATLANTIC BEACH TREE INVENTORY
DEFINITION OF VISUAL CHARACTER
A COMPOSITION OF THE FOLLOWING MAIN ELEMENTS
DEFINE THE VISUAL CHARACTER OF A STREETSCAPE:
ARCHITECTURE LAND USE
VEGETATION (TREES) UTILITIES
TERRAIN/TOPOGRAPHY MAINTENANCE
ROADS/DRIVES WATER
ACTIVITY (VEHICULAR) ACTIVITY (PEDESTRIAN)
THE MEASUREMENT & EVALUATION OF THE IMPACTS OF DRAINAGE
IMPROVEMENTS ON MAJOR CORE CITY TREES & THE PROTECTION MEASURES
REQUIRED TO REDUCE TREE LOSS WILL BE THE FOCUS OF THIS STUDY.
DIVERSITY OF TREE
VEGETATION IS THE MAIN
VISUAL ELEMENT THAT LAUREL OAK
DEFINES VISUAL CHARACTER
IN THE CORE CITY AREA
LIVE OAK Mr
IIl,' LL- SABAL PALM
fiA
fiiiir;:uf.710‘ # lk .112,.....'Imutr.
47 -
11 •
771a..
1m—
itt',,
1.-, • RED It i::i g '..
CEDAR AV HICKORY ii`
2-4/-1 : 1r i a:a'
MAGNOLIA
TYPICAL TREE SPECIES THE CORE CITY AREA. DRAINAGE SYSTEM ANALYSIS
THE POTENTIAL MPACTS TO MAJOR TREES
LIVE OAK SOUTHERN RED CEDAR IN THE CORE CITY AREA IS DETERMINED BY
1
THE AMOUNT OF DAMAGE TO ROOT ZONES. ROOT ZONE DAMAGE
tLAURELOAKSABALPALMETTO IS COMPAR TO THE POTENTIAL IMPACTS OF THE ETM DRAINAGE
1 IMPROVEMENT PLANS.
SOUTHERN MAGNOLIA SLASH PINE
THE METHOD OF DETERMINING TREE LOSS AND PROTECTION
PECAN RED MAPLE MEASURES TO LIMIT THIS LOSS IS ILLUSTRATED IN
S
FIGURES V.2- V.9
LIGUSTRUM WATER OAK
CRAPE MYRTLE SYCAMORE
FIGURE V.2 METHOD OF MEASUREMENT
CITY OF ATLANTIC BEACH VEGETATION
CHARACTERISTICS OF ROOT ZONES
1. ROOT ZONES GENERALLY EXTEND BEYOND THE DRIPLINE OF THE TREE.
2. ROOT ZONES ARE GENERALLY IRREGULAR IN SHAPE & PATTERN.
3. ROOTS GROW WHERE SOIL NUTRIENTS, MOISTURE AND SUFFICIENT AIR EXIST.
4. 85% OF A TREE'S MAJOR ROOTS EXIST IN THE UPPER 18" OF THE SOIL.
5. 99% OF THE TREE'S ROOTS CAN BE FOUND IN THE UPPER 3 FT. OF SOIL.
6. THE ESSENTIAL MASS OF ROOTS IS USUALLY FOUND WITHIN THE DRIPLINE OF THE TREE
7. ONCE DAMAGED, ROOTS CANNOT HEAL THEMSELVES.
ROOT ZONE
20" DBH TREE
EXTENT OF ROOT ZONE
R=20'
111/-1
DEPTH OF ROOT ZONE a
18"—
j
36"
r
ROOT ZONE
20" DBH TREE 1 IEXTENT OFROOTZONE
PLAN VIEW
A GOOD RULE TO ESTABLISH THE EXTENT OF THE ROOT ZONE IS TO CONVERT THE DBH INCHES OF THE TRUNK TO A RADIUS
IN FEET AWAY FROM CENTER OF TRUNK.
EFFECTS OF CONSTRUCTION ON TREES.
1. SOIL COMPACTION— CRUSHING OF ROOTS, MATTING, LOSS OF AERATION, OXYGEN, NUTRIENTS, SOILS MAY BECOME IMPERVIOUS
2. EXCAVATION— RIPPING, TEARING, SEVERING OF ROOTS.
3. FILLING — ROOT SUFFOCATION, PROMOTES FUNGAL GROWTH, CHANGES MOISTURE/NUTRIENT REQUIREMENTS.
4. EROSION/SEDIMENTATION— SUFFOCATION, LOSS OF WATER & NUTRIENTS.
5. DRAINAGE CHANGES— CHANGE OF MOISTURE REQUIREMENTS ON SITE WILL DAMAGE TREES.
6. BREAKS, SCRAPES, SCARRING— WOUNDS TO TRUNKS do LIMBS WILL ALLOW PESTS AND DISEASE TO ATTACK TREE.
7. CONTAMINANTS— CHANGE IN SOIL CHEMISTRY CAN DAMAGED TREES.
FIGURE V.3 FLOODING
CITY OF ATLANTIC BEACH HOWELL PARK
HOWELL PARK HAS THE SPECIES COMPOSITION OF A
BOTTOMLAND) LOWLAND MARITIME FOREST.
LOWLAND
TEMPORARY FLOODING A BOTTOMLAND FOREST CAUSES: MARITIME
1. DEPOSITION OF SUSPENDED SOIL PARTICLES AND POLLUTANTS. J FOREST
2. MATS & CONCENTRATES THE ORGANIC SOIL LAYER J
3. SMOTHERS & SUFFOCATES THE ROOT SYSTEM.
4. PROMOTES GROWTH OF FUNGI ON TRUNK
CERTAIN TREES HAVE DEVELOPED ROOT SYSTEMS j`THAT TOLERATE FLOODING & BOTTOMLAND SOIL: p ob
BALD CYPRESS SLASH PINE
WATER TUPELO RED BAY
BLACK GUM SWEET BAY 4'1'4oh" a
WILLOW CABBAGE PALM A1;11'i'
WATER t•=1'1 1
RED MAPLE LEVEL
Nil „I
n Ott` '
7''LOBLOLLY BAY
o
SWEETGUM RIVER BIRCH
THESE TREE SPECIES EXIST IN HOWELL PARK.
THESE TREE SPECIES WILL SURVIVE INTERMITTANT FLOODING.
FLOODED AREAS WOULD HAVE TO DRAIN FREQUENTLY; RECEDING WATER LEVEL
HOWEVER. SOILS CAN REMAIN MOIST.
HYDRIC SOILSFREOUENTFLOODINGWILLCHANGESPECIESCOMPOSITION.
SHALLOW ROOT SYSTEM
HOWELL PARK- PREVIOUS HISTORY OF FLOODING
REQUIRES EVALUATION.
EVALUATION FOR TREE SURVIVAL SHALL INCLUDE:
DURATION OF FLOODING
FREQUENCY OF FLOODING
DEPTH OF WATER DURING FLOODING.
TYPE OF TREE SPECIES
TREES THAT WOULD HAVE SOME DIFFICULTY SURVIVING FLOODING:
SOUTHERN MAGNOLIA
LIVE OAK
LAUREL OAK
Eighty major trees have been identified in the Core City area from Ahern
zt
Street northward to Eleventh Street and from Sherry Drive eastward to East Coast
g : Drive. These trees have been identified as having potential impacts from
f construction of the drainage improvement system. Of the 80 major trees identified,
25 live oaks and one magnolia are classified as unique or specimen trees according
to the City of Atlantic Beach Tree Protection Ordinance. Figures V.4 through V.6
show the size and species of major trees located along each street that could be
damaged by construction.
B. Project Impact on Trees
The intent of this analysis is to minimize or eliminate any possible damage
to root zones by the proper planning of the new drainage system. Additional tree
protection measures will increase chances of tree survival.
Any spreading tree located near the street right-of-way is subject to damage
from construction. Soil compaction, excavation, soil filling, and trunk damage are
potential hazards that could ultimately kill the trees in the construction zone. Figures
V.2 and V.7 identify the general effects of construction on existing trees.
To minimize tree damage in the Core City, the majority of the drains work
will occur between the edges of the existing pavement. Existing street grades should
not be altered more than a few inches. With the current R-A-M Team concept
envisioned, soil compaction and filling are insignificant impacts that would not effect
the tree's health. However, during the final phase of design, filling and compaction
of soil may require evaluation to determine potential damage to roots.
Excavation for placement of drainage, sanitary sewer, and waterlines will
have some impact on the majority of root zones.The extent of that damage should
be restricted whenever possible by proper alignment and layout of pipes and inlets.
New utility lines should be installed on the opposite side of the street, away from
each subject tree that might be impacted. Figure V.8 illustrates a proposed typical
plan and section alignment of utility lines in reference to a tree's root system. The
National Arbor Foundation advises that 35% to 40% destruction of a tree's root area
will ultimately kill the tree; 25% to 35% root destruction would place the tree in a
stressful condition and survival could be marginal depending on its current health.
v of Atlantic Beach Page V-2 Preliminary Design Report
re City Redesign/Tailwater r March 15, 1999
ii
do h 1Ac..( T,L Ie a i 0c;..( rv:; L( 6t rk c i\r\cy-v-4-c, (g
CITY 6 ATLANTIC BEACH, FLORIDA
IMPACT OF DRAINAGE IMPROVEMENTS ON MAJOR TREES
FIGURE V.4
I
WSURVIVABILITY PROPOSED UTILITY
N TREE DBH SIZE & SPECIES TYPE ESTIMATED IMPACT ON ROOT ZONE
POTENTIAL LOCATION/ SUGGESTED
PROTECTION MEASURES
24" LIVE OAK LOW, 5% GOOD. 95%
Z
1- DRAINAGE LINEW
W 22" LAUREL OAK LOW, LESS THAN 5% GOOD, 95% PROPOSED ON SOUTHSIDE
y OF ROADWAY;
21" LIVE OAK LOW. LESS THAN 5% GOOD. 95%
34" LAUREL OAK LOW. 10% GOOD. 90% UTILITIES- SOUTHSIDE
OF ROAD FROM STA.
22" LIVE OAK LOW. LESS THAN 5% GOOD, 95% 10+00-11+00, JOG NORTH
O STA. 11+15; JOG SOUTH
4O" LIVE OAK MODERATELY HIGH. 25% MARGINAL, 75% 0 STA. 14+00; CONTINUE
W ON SOUTHSIDE TON
41' LAUREL OAK MODERATELY HIGH. 25% MARGINAL, 75% EAST COAST DRIVEliN
AUGER WATERLINE
27" LIVE OAK LOW, 10% GOOD. 90% UNDER ROOT ZONES
27' UVE OAK LOW TO NONE GOOD, 95%
UTILITIES- NORTHSIDE34' LIVE OAK LOW. LESS THAN 10%GOOD. 90% OF ROAD FROM STA.0''
10+00-12+50. JOG SOUTHOw •36" LIVE OAK LOW, LESS THAN 10% G000, 90% 0 STA. 12+50; CONTINUE
w ON SOUTHSIDE TO
vl v) 24' LIVE OAK LOW. LESS THAN 10% GOOD. 90% EAST COAST DRIVE
AUGER WATERLINE
18" LIVE OAK LOW. LESS THAN 5% GOOD, 95% UNDER ROOT'ZONE
20" UVE OAK LOW, 10% GOOD. 90%
4.0" LAUREL OAK LOW. 57. GOOD, 95% UTILITIES- NORTHSIDE
F OF ROAD FROM STA.
20" LIVE OAK (X) HIGH, 30%- 407. POOR 10+00-15+00. JOG SOUTH
0 STA. 15+00; JOG NORTH
e w• 34' MAGNOLIA NONE GOOD. 100% 0 STA. 16+25; CONTINUE
N ON NORTHSIDE TO
34" LIVE OAK LOW, LESS THAN 5% GOOD. 95% EAST COAST DRIVE.
AUGER WATERLINE
22" LIVE OAK LOW TO NONE GOOD. 95% UNDER ROOT ZONES
19" LIVE OAK LOW, 10% GOOD, 90%
48" LIVE OAK• LOW 15%, SPECIAL ATTENTION REQUIRED FAIR TO GOOD. 85% UTILITIES- SOUTHSIDE
OF ROAD FROM STA.
40" LIVE OAK MODERATE. 20%; ALREADY STRESSED MARGINAL. 70% 10+00-11+00. JOG NORTH
O STA. 11+00.
36" LIVE OAK MODERATELY HIGH, 25% MARGINAL, 75% CONTINUE ON
NORTHSIDE TO
ce w 21 " LIVE OAK LOW. LESS THAN 10% GOOD. 90% EAST COAST DRIVE.
L.L.
D CCAUGER01-LINE
U) 18" LIVE OAK LOW TO NONE GOOD, 95% UNDER ROOTRZONES
18" CEDAR MODERATE, 15%- 207.FAIR, 80%
24" LIVE OAK LOW, LESS THAN 107.GOOD, 90%UTILITIES- SOUTHSIDE
56" LIVE OAK• ABOUT 10X, SPECIAL ATTENTION REQUIRED GOOD, 90% OF ROAD FROM STA.
F
10+00-14+50. JOG NORTH
0 STA.
i W 25" LIVE OAK LOW TO NONE GOOD. 95%
CONTINUE4+
50;
ixL.
ON NORTHSIDE TO4w •34" LIVE OAK MODERATE. 15%- 20%FAIR, 80%EAST COAST DRIVE.
24" LIVE OAK LOW TO NONE GOOD. 95%
AUGER WATERLINE
UNDER ROOT ZONES
UTILITIES- SOUTHSIDE
56" LIVE OAK•
OF ROAD FROM STA.
25%- 30%, SPECIAL ATTENTION REQUIRED — MARGINAL. 70%10+00 TO
EAST COAST DRIVE.
25" LIVE OAK LOW TO NONE GOOD. 95% AUGER WATERLINEvl
UNDER ROOT ZONES
DESIGNATES UNIQUE OR SPECIMEN TREE. REQUIRES SPECIAL ATTENTION
NOTE: POTENTIAL ROOT DAMAGE BY SOIL FILLING OR COMPACTION NOT INCLUDED IN ANALYSIS.
NOTE: ROOT PRUNE ALL TREES DURING EXCAVATION AT IMPACTED AREA.
CITY OF ATLANTIC BEACH, FLORIDA
IMPACT OF DRAINAGE IMPROVEMENTS ON MAJOR TREES
FIGURE V.5
LiLi
SURVIVABILITY PROPOSED UTILITY
TREE DBH SIZE & SPECIES TYPE ESTIMATED IMPACT ON R00O ZONE
POTENTIAL LOCATION/ SUGGESTED
t^PROTECTION MEASURES
30" LIVE OAK LOW, LESS THAN 10% GOOD. 90% UTILITIES- SOUTHSIDE
OF ROAD FROM STA.
36" LIVE OAK MODERATE, 20%- 25%MARGINAL, 75%- 807. 10+00-15+00, JOG NORTH
O STA. 15+00: JOG SOUTH
w 28 LIVE OAK LOW, 10% GOOD. 90% 0 STA. 17+00; CONTINUE
w0- ON SOUTHSIDE TO
N 18" MAGNOLIA LOW TO NONE GOOD, 957.- 1007. EAST COAST DRIVE
AUGER WATERLINE
18 MAGNOLIA LOW TO NONE GOOD, 95%- 100% UNDER ROOT ZONES
25" LIVE OAK (X)HIGH, 40% POOR, ALREADY STRESSED UTILITIES- NORTHSIDE
OF ROAD FROM STA.
46" LIVE OAK MODERATE, 257. MARGINAL, 757. 10+00-16+00, JOG SOUTH
I-LiL'-' m STA. 16+00; CONTINUE
F.5 29 LIVE OAK LOW. 107. GOOD, 907. ON SOUTHSIDE TO
CD i EAST COAST DRIVE
24" CEDAR LOW TO NONE GOOD. 95%- 1007. AUGER WATERLINE
UNDERROOT ZONES
12" LIVE OAK LOW TO NONE GOOD, 957.- 1007.
30" LIVE OAK LOW, 157. FAIR TO GOOD, 85% UTILITIES- NORTHSIDE
OF
w •30 LIVE OAK LOW, 157.110+00-D1O+75. JOG SOUTH
I-wFAIR TO GOOD, 85%
z NONSSOUTHSIOE TO
CONTINUE
25" LIVE OAK LOW. LESS THAN 10% GOOD, 90% EAST COAST DRIVE
AUGER WATERLINE
45" LAUREL OAK LOW. 10% GOOD, 90% UNDER ROOT ZONES
0,4 22" LIVE OAK LOW, 10% GOOD, 90%
w< PLACE UTILITIEUIN
H
14" SYCAMORE (X) MODERATE TO HIGH, 30%- 35% POOR, 657.
CENTER OF SOUTH LANE.a
15" LIVE OAK NONE GOOD, 100% UTILITIES- SOUTHSIDE
OF ROAD FROM STA.
27 LIVE OAK NONE GOOD, 100%10+00. CONTINUE TO
zW EAST COAST DRIVE.
cc 24" LAUREL OAK 15%, POOR CONDITION POOR. 50% AUGER WATERLINE
v UNDER R00T ZONES.
24- HICKORY LOW, LESS THAN 10% GOOD. 90%
38" LAUREL OAK LOW, LESS THAN 10% GOOD, 90%
30" LAUREL OAK LOW, LESS THAN 5% GOOD. 90%
UTILITIES- SOUTHSIDE
w 20 LAUREL OAK LOW TO MODERATE, 15% FAIR TO GOOD. 857.OF ROAD FROM STA.
w 10+00-16+00, JOG NORTH
0 STA. 16+00; JOG SOUTH
wE 16",14",12" LIVE OAK LOW TO NONE, 57. GOOD. 95%0 17+00, CONTINUE
ON
ASTT COAST
18" MAGNOLIA LOW, LESS THAN 157. GOOD. 85% EAST
TO
EAT DRIVE.
16" LIVE OAK LOW, 10% GOOD, 90%
AUGER WATERLINE
UNDER ROOT ZONES
30" LIVE OAK LOW. LESS THAN 107. GOOD, 90%
23" LIVE OAK LOW, LESS THAN 57. GOOD. 95%
DESIGNATES UNIQUE OR SPECIMEN TREE, REQUIRES SPECIAL ATTENTION
NOTE: POTENTIAL ROOT DAMAGE BY SOIL FILLING OR COMPACTION NOT INCLUDED IN ANALYSIS.
NOTE: ROOT PRUNE ALL TREES DURING EXCAVATION AT IMPACTED AREA.
1110
CITY OF ATLANTIC BEACH, FLORIDA
IMPACT OF DRAINAGE IMPROVEMENTS ON MAJOR TREES
FIGURE V.6
LiWLLIcc TREE DBH SIZE & SPECIES TYPE ES1TMATED IMPACT ON ROOT ZONE
SURVIVABILITY PROPOSED UTILITY
UGGESTEDPOTENTIAL
PROTECTION
LOCATIN/ SMEASURES
23" LIVE OAK LOW, LESS THAN 57. GOOD, 95%
UTILITIES— DRAINAGE
17",15",15 LIVE OAK LOW TO NONE, 0— 5%GOOD. 95% LINE INSTALLED 3'
WEST OF EAST EDGE
15" LIVE OAK LOW TO NONE, 0— 57.GOOD 95%— 100% OF SHERRY STREET.
SAN. SEWER LINE
38" DBL. LIVE OAK LOW, 57. GOOD. 95% INSTALLED ALONG
CENTERLINE OF SHERRY
32" DBL. LIVE OAK LOW, 57. GOOD, 957. STREET WATERLINE
INSTALLED ALONG
24" LIVE OAK LOW, 5%GOOD, 95% CENTER OF
SOUTHBOUND LANE
30" LIVE OAK LOW, 5% GOOD. 957. OF SHERRY STREET.
48 LIVE OAK• MODERATE, 207. FAIR, 80%
r, 27" LIVE OAK LOW TO NONE
cc W
GOOD, 959.— 100X
W cc 19' CEDAR LOW TO NONEx
in L'
GOOD, 95%
31" SYCAMORE LOW, 5X-10X GOOD. 90%
48" LIVE OAK• (DUPLICATED) MODERATELY HIGH. 35% GOOD, 90X
42" LIVE OAK• MODERATE, 20% FAIR, 80%
56" LIVE OAK' (DUPLICATED) MODERATELY HIGH, 25%— 30%MARGINAL, 70%
24" LIVE OAK LOW, 5% GOOD, 95%
32" LIVE OAK LOW, 107. GOOD. 90%
32" LIVE OAK LOW, 5% GOOD, 95%
30" LIVE OAK LOW TO NONE GOOD, 95%
44", 26" LIVE OAK•LOW. 10% GOOD, 90%
DESIGNATES UNIQUE OR SPECIMEN TREE. REQUIRES SPECIAL ATTENTION
NOTE: POTENTIAL ROOT DAMAGE BY SOIL FILLING OR COMPACTION NOT INCLUDED IN ANALYSIS.
NOTE: ROOT PRUNE ALL TREES DURING EXCAVATION AT IMPACTED AREA.
FIGURE V.7
4110/ CITY OF ATLANTIC BEACH
METHODS OF CONSTRUCTION
FILL ON TREE ROOTS
SMOTHERS TREES ROOTS
MATS THE ORGANIC SOIL LAYER
CHANGES THE MOISTURE LEVEL OF THE SOIL.
ROOT AREA IMPACTED
BY FFILLING
O 411
sa
IIII=III_
ienn=uu1
V.‘""'"•
ROOT ZONE DAMAGED
BY
ROOT
FILLING
407. DAMAGE
TRENCHING
ROOT AREA SEVERED
BY TRENCHING
r
0
a
ROOTS DAMAGED
BY COMPACTION OF4.1111 TRENCHING EQUIPMENT
ROOT AREA COMPACTED
BY TRENCHING EQUIPMENT
ROOT SEVERED
BY TRENCHING
407. ROOT KILL.)
WHEN 357. TO 407. OF THE ROOT ZONE IS IMPACTED BY CONSTRUCTION, THEN THE TREE
WILL PROBABLY DIE AND SHOULD BE REMOVED AND MITIGATED.
FIGURE V.8
CITY OF ATLANTIC
IMPACT ON VEGETATION
BEACHCMETHOD OF EVALUATION
TYPICAL
ELEVATION
AT MAJOR TREES WITHIN
ALL CORE CITY AREAS
L--
ill‘A41, ---C/L
1, 1,• ROADWAY
9* X 10"- 14' CURB
r'c-_ =.! _ _;, RIBBON CURB
n. r AREA OF EXCAVATION2
DRAINAGE
i PIPE
AUGER WATERLINE SANITARY
UNDER ROOT ZONE SEWER LINE
85% r 15%
I PRESERVED ROOT ZONE I ROOT ZONE 1
REMOVED-
PRUNE ROOTS
PRIOR TO EXCAVATION
ii
II
EXTENT OF II fDRAINAGE
ROOT ZONE I • PIPE
0
000#
TREE TRUNK ROOT ZONE
O
REMOVED
11111111
TYPICAL
PLAN
AT MAJOR TREES WITHIN
ALL CORE CITY AREAS
it
II
1
1.
II SANITARY
0 AUGER WATERLINE
UNDER ROOT ZONE
SEWER LINE
111
The Project Engineer and Landscape Architect conducted an extensive field
inventory to document existing tree driplines, health, and impacts from the proposed
t, Core City utility system recommendations.The characteristic and area of each major
k root zone were delineated on the tree survey that was prepared and furnished to the
Ake' k
Team by ETM.As graphically summaried in Figure V.8, the R-A-M Team Core City
utility redesign recommendations were then superimposed upon the ETM tree
survey to indicate impacts upon each delineated root zone. The area and
percentage of root zone damage was estimated and noted. Figures V.4 -V.6 depict
each tree's size and species,the estimated impact on each root zone,the estimated
survivability potential,and the proposed utility line location with suggested protection
measures.
Based on the evaluation of the R-A-M Team concept, 62 major trees would
have less than 10% root damage with a 90% or better chance of survival. Another
seven trees would have an 80%or better survivability potential. Seven trees would
be characterized as marginal with no less than a 70% chance of survival. Only four
trees would have impacts that exceed accepted limits of survivability.
40
C. Decreased Tree Loss
When excavating in the root zone area, root pruning will increase the
chances of tree survival as opposed to tearing roots with backhoe equipment.
Whenever possible,the work should be limited to areas where the roots are 2 inches
in diameter or less. Generally, trenching equipment will provide clean cuts to roots
less than 2 inches in diameter without damage to the main leaders. If roots are larger
than 2 inches in diameter, then hand pruning is required to provide clean cuts and
prevent damage along the leader. Cleanly severed root ends of greater than 2
inches should be wrapped and tied with burlap immediately after the cut. The
effected area should be watered frequently during the day to minimize stress on the
tree.Tree roots should never be exposed for more than 12 hours without treatment.
All exposed roots should be covered immediately with peat and kept moist if
backfilling cannot occur during the same day. Impacted root zones should remain
moist until construction is complete. The drying of exposed roots will cause
additional dieback and may kill the tree.
Another method of protecting trees is to install utility lines below roots by
auger as opposed to trenching. Augering, although somewhat expensive, can
preserve substantial root structure and save a tree which would die from trenching.
City of Atlantic Beach Page V-3 Preliminary Design Report
Core City RedesignlTailwater Cont, March 15, 1999
Angering is recommended for waterline installation in the Core City, especially in the
1 root area of the 26 unique or specimen trees.
iFilling or stockpiling of soil on tree roots should not occur unless protection
measures are planned. The use of retaining walls or aeration systems should be
designed as illustrated in Figure V.9. Low retaining walls can be constructed of
landscape timbers and eliminate any fill area on the root zone. Aeration systems
allow the tree's root system to maintain access to life-supporting air, water, and
nutrients.
A trained professional should be involved during the construction of the new
drainage system. An arborist, urban forester, or qualified tree specialist should be
engaged to monitor the construction process and consult with the contractor during
all phases of work. A professional on the construction site is especially important
during initial phases of construction to monitor the excavation work and advise
necessary root pruning, treatment, and protection practices for specimen trees.
V- By comparing the proposed R-A-M Team Core City utility redesign
ab
7 recommendations with the design plans prepared by ETM, tree loss would be
substantially reduced. When reviewing the location of proposed utility lines on the
c ETM plans,approximately 42 of the 80 trees evaluated in the project area would
1(1:\
y
sustain enough root damage from excavation to cause severe decline or even death.
v` Only 11 major trees are noted as having a 75% or less chance of survival in the
Sc , proposed R-A-M Team concept. The R-A-M Team concept would reduce root
r .
d
impacts from excavation and subsequent tree loss over 5 years by an estimated
75%.
D. Mitigation Plan
Tree mitigation is based on the City of Atlantic Beach Tree Protection
Ordinance No. 95-95-64. Replacement is calculated from estimated losses of four
major trees within a one-year period and a potential loss of seven major trees over
a five-year period. Minor protected trees and palms were not included as part of this
analysis, since damage should be minimal under the R-A-M Team redesign concept.
However, further analysis during the next phaseof design should identify potential
damage to these trees and additional losses. The following tree replacement
410
schedule identifies the mitigation requirements for the project.
Cl-. Atlantic Beach Page V= Preliminary Design Report
v Redesign/Tailwater Cc-- March 15, 1999
iFIGURE V.9 CONSTRUCTION
CITY OF ATLANTIC BEACH CONTROL TECHNIQUES
PROTECTION
x x II-
MEASURES ROOT
ZONE IIIHIGHVISIBILITY
BARRICADES O PLASTIC MESH
REROUTE DRAINAGE SYSTEMS x OR CHAINLINK r
AROUND BARRICADES x FENCING.
WHEN PRACTICAL.
is :•:•:f:::::: :: •
x x
EXTEND BEYOND
i DRIPLINE OF TREE
ii
i
TRENCH TO1,7
ROOT ZONE
2
iliab—
AUGER BELOW TREE ROOTS ZONE
J^/<
HOLE DIAMETERS- 2'- 48') t
O
INSTALL
410 UTILITY LINES
BY AUGERING
ZBELOWROOT
ZONE. A 0 TUNNEL & PIPE
BELOW ROOT ZONE.
24"
ROOT
ZONE r l
AERATION OF A FILL SITE 0 FILL AREA r
CEOTEX. FABRIC -
FILL AREA
GRAVEL OR ROCK BED
1-1/2' SCH. 40 PVC LANDSCAPE TIMBER
PERFORATED PIPE EDGE
ROOT
ZONE
o
RETAINING WALLS a 0
W FILL AREA r
D.
o'o III=
vl
vJi 1111=W1=
y
JII 1111IIU T NATURAL GRADEIIIIiIIII(I'`
USE RETAINING WALLS TO CU
PROTECT ROOTS AREA
FROM GRADE CHANGE.
Estimated Tree Losses Estimated Tree Losses
in One Year in Five Years
20" Live Oak 40" Live Oakc .`
24" Live Oak 41" Laurel Oak
14" Sycamore 40" Live Oak
24" Laurel Oak 36" Live Oak
83" of Trees 56" Live Oak
36" Live Oak
83" @ 50% Replacement=42" 46" Live Oak
295"of Trees
295" @ 50% Replacement= 148"
Replacement of 42 caliper inches is estimated within the first year of
construction. Planting 11 (4-inch caliper)live oaks would fulfill the initial replacement
requirement.Within five years, 148 caliper inches are estimated for replacement due
to possible long-term tree losses encountered from the construction. The five-year
estimate for tree removal and replacement is conservative, since some or all of
these trees may survive. However, 37(4-inch caliper)live oaks are proposed to fulfill
this mitigation requirement. Recommended planting locations would include open
areas along the Sherry Drive and Seminole Road rights-of-way.
E.Construction Control Techniques
Construction control techniques to reduce tree losses include good planning
practices, use of tree barricades, root pruning, augering of utility lines, treatment of
fill areas, and project monitoring. Figure V.9 illustrates additional protection
measures that will greatly improve the chances of tree survival during construction.
Planning is the best control measure that will preserve trees in the
construction area.Whenever possible, the utility system should be planned around
the tree's vital root structure. In the Core City area this construction practice is not
always feasible or practicable because of narrow streets and spreading root
systems. However, the next phase of design should include referenced provisions
for reducing root zone impacts on a tree-by-tree basis.
Root damage can be controlled by proper placement of tree barricades
before construction equipment is delivered to the job site. Proper planning and
City of Atlantic Beach Page V-5 Preliminary Design Report
Core City Redesign/Tailwater Control March 15, 1999
placement of barricades directly adjacent to the limits of excavation work will reduce
potential root damage. Barricades should also be used to control construction traffic
and stockpiling of materials. Both practices will eliminate unnecessary compaction
of the soil above the root zone. Barricade construction should also be monitored and
adjusted through all phases of construction.
F.Cost Summary
ETM estimated tree mitigation within the Core City street rights-of-way to be
about $102,000. By incorporating measures presented previously, which should
cost about $137,000, the mitigation costs are expected to be reduced to $25,000.
Accordingly, a net increase of about$60,000 is likely to be required, but as indicated
above, should result in the survival of at least 75% more trees than the ETM design.
City of Atlantic Beach Page V-6 Preliminary Design Report
March 15, 1999Core ^ edesignRailwa+of
Details
5.2 Residential streets
7,-;;;;..Z4e...-4, .. „,.....,...e11--,&,:;.04-`it:-:'
st':,. :.Zr.
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z R ,..".t7:,......:.'4,•-,,,,z.47,-
ti
x , e2 'Wii $ l , 1 aL
r
r_j^
A typical pre-war street A typical post-war street
28 foot wide with tree-lined parkway between the curb and 36 foot wide with no parkway between sidewalk and curb.Note
sidewalk.This traditional design can be found in older neigh- how few vehicles occupy the street,even though a great deal of
borhoods throughout the Bay Area. area is paved.
2 Residential streets. Residential streets are at the nexus Prior to World War II, traditional residential streets were de-
of a wide variety of land use and environmental issues.An un- signed as multiple use spaces,shared by pedestrians,children at
derstanding of their scope, history, and function helps to ex- play, animals, and low volumes of vehicular traffic traveling at
plain their central importance in the design of residential devel- low speed.The prototypical residential subdivision,laid out by
opment for stormwater quality. Frederick Law Olmsted at Riverside, Illinois, in 1869, has 24
feet wide streets with concrete curb and gutter,lined with broad
Considered a number of ways, the street is a large design ele- 12 foot wide parkway strips planted with trees. Outside of the
ment. In a typical residential neighborhood, the public right- parkway strip is a 5 foot wide sidewalk on both sides.25 This
of-way — the street — comprises approximately 20 to 25% of model was copied all over the United States,and many pre-war
total land area, making it the single most important determi- neighborhoods can be found today with similar traditional street
nant of neighborhood character.Streets also can comprise up to geometries.
70%of a community's total impervious land coverage,with the
remainder of impervious land coverage from rooftops and other After World War II, new street standards were developed to fa-
structures.This makes street design the single greatest factor in cilitate the automobile,which was growing both in dominance
a residential development's impact on environmental quality. and number. Standards set by professional associations such as
Finally, because the street exists in the public right-of-way, it the Institute of Transportation Engineers (ITE) and the Ameri-
comprises nearly 100% of public open space in a typical resi- can Association of State Highway and Transportation Officials
dential community. Because it is located in the public right-of- (AASHTO) as well as rules promulgated by the Federal Hous-
way, it is subject to municipal ordinances, standards, and man- ing Administration increased paved area by up to 50% corn-
agement, giving local jurisdictions a great deal of control over pared to pre-war designs,setting typical residential street width
street design. For these reasons, the street is the single most at 36 feet,plus curb,gutter and 5 feet of sidewalk on both sides.'-
portant design element in residential site planning, and the These standards were applied in communities throughout the
ement that can be most directly affected by local ordinances Bay Area and the United States. For ease of maintenance,many
and policies. communities abandoned the parkway strip between the curb
and sidewalk, bringing the sidewalk flush with the back of the
Hr ''..:" rn,r \lel a '"'"' ALe'.,c•;..,''''""
r .
Details
5.2 Residential streets (continued)
local street
access street serves neighborhood
serves abutting properties 500 to 1,500 ADT
c500 ADT moderate pavement
least pavement width
width
14000.•
440111".
4.
j/4= r
i/.
4-Z,---- ,. -40
collector or arterial
bounds neighborhood
1,500 ADT
greatest pavement width
5.2a Street hierarchy
curb and eliminating the street trees. In a typical 50 foot wide age daily traffic (ADT) of less than 1,500 vehicles. Through4111)right-of-way, this 46 foot wide standard pavement section (36 traffic and truck traffic is generally discouraged on local streets.
feet of street plus 10 feet of sidewalk) creates 92% impervious Collector streets are an intermediate class,intended to collect traffic
land coverage in the right-of-way. Compared to the inviting, from local streets and deliver it to larger arterial streets. They
park-like space of the original Olmsted model, with its 57% also can serve as the primary traffic route within a residential or
impervious land coverage(34 feet of pavement inside a 60 foot commercial area, and have a typical ADT between 1,500 and
right of way),the modern residential street can be a hot,treeless 3,000. Finally, the largest class (except highways and freeways),
place. arterial streets, have an ADT between 3,000 and 10,000, and
are intended to provide long distance travel, with controlled
Today professionals from many fields,including transportation intersections and higher speeds. For residential design, local
engineers, landscape architects, urban designers, and environ-
streets are most relevant.
mental scientists, are reevaluating residential streets with the
intent of creating new standards that are more hospitable and A survey of Bay Area municipalities reveals that the typical
that are more environmentally responsible.New street standards current standard for a two-way local street with parking on
based on the pre-war models (known as "neo-traditional de- both sides requires two moving lanes, plus two parking lanes,
sign")are now being studied and adopted in municipalities across plus curb, gutter and sidewalks each side, making a total of 40
the country.At the national professional level,a technical com- to 50 feet of pavement within a typical 50 foot right-of-way
mittee of the ITE is currently considering neo-traditional street (see table).
standards that permit local streets between 22 and 30 feet wide,
Yet, the number of vehicle trips on a local street can vary conallowingparkingonbothsides,with or without curbs.
siderably,depending on the number of abutting dwelling units.
5.2a Street hierarchy. Municipal standards generally clas- Given the generally accepted rule-of-thumb for residential street
Ssift'street widths by the planned function of the street: local, design of 10 vehicle trips per day per dwelling unit,a street with
collector or arterial. Local streets, the smallest class,are intended ten single family homes can be expected to generate an ADT of
to provide access to abutting properties,and have a typical aver- 100, or an average of one vehicle trip approximately every 15
38 Start of tl.•Source-Rnidrnual Sur Planning Sc Design Guidance Slanual for Scormwacer Qualm.Proccction
curb/gutter required
A
o e. parking Lane
50'
56 A< Ilb %lit
both sides
77-
i'''' .-- -''''''..-
t->".". ')".-j
sidewalk
no parkway two moving
planting vehicle lanes
Typical current standard for a local street:
90 % impervious land coverage
Impervious land coverage and street design standards.
Most Bay Arca municipal street standards mandate over 80%imper-
vious land coverage in the public right-of-way.Alternative standards4111minutes (every 6 minutes in the peak hour). In comparison, a can significantly reduce impervious land coverage while meeting ac-
local street serving one hundred homes (1,000 ADT) will gen- cess needs of local,residential streets.
erate an average of one vehicle trip every 90 seconds (every 30
seconds in the peak hour).When built to typical municipal stan- Representative local street standards for Bay Area municipalities.
dards, the two mandated moving lanes of a local street uses a
Jurisdiction Street curb/gutter sidewalk parkway r.o.w.
great deal of land area for very little traffic. If the street is con-width required required planting impel
sidered in terms of space, rather than lanes,a central space wide
enough for one vehicle can be retained for movement,with park- Alameda Co. 40 ft. yes 5'/side no 100%
ing and waiting space along both sides. In the infrequent in- Concord 36 yes 4'/side varies 90%
stance when two vehicles approach in opposite directions, one Contra Costa Co. 32 yes 4'/side no 78%
vehicle can pull into the parking lane to allow the other vehicle Palo Alto 40 yes 4'/side yes 85%
to pass in the central moving space.The many driveway open-
ings on either side of the street ensure than at any given seg
San Jose(std.) 35 yes 5'/side no 100%
ment of the street some space will be available for waiting,even San Mateo Co. 36 yes 4'/side no 94%
j if parking spaces are full on both sides.On lightly traveled streets,
the minor inconvenience of waiting for oncoming traffic does Alternative street standards for local and access streets.
not occur very often, making a shared central moving space Neotraditional 28± no 4'± yes 74%
feasible for streets serving up to 50 dwelling units (500 ADT, Rural 20± no no yes 36%
one vehicle every 3 minutes average,every 1.5 minutes peak).' San Jose(alt.)-I- 30 yes 4'/side yes 81%
Unlike most municipal standards,which set street width by num- (All standards reflect minor or local street standards for flat areas to
ber of vehicle lanes and roadway classification (local, collector, accommodate two way traffic,with parking both sides,typical right-
i•of-way between 45 and 60 feet wide.)
arterial), street design by anticipated traffic volumes (ADT) al-
lows for varying pavement width to match usage. Using the t San Jose Narrow Residential street standard,parking one side only.
39
Na, Arca tuam„atcr Management AL'enot,'kWh:U[1W
r Details
5.2 Residential streets (continued)
curb/gutter optional
parking/waiting spaceu /'
i' /one or both sides)
56
4.
sidewalk i7,,,
with parkway planting
shared central
moving space
5.213 Access street: urban nee-traditional standard
74t% impervious land coverage
analogy of stream flow, this "headwaters streets" system allows Two types of access streets can be built using neo-traditional
the most"upstream"streets,those serving approximately 50 ad- standards: rural or urban.
jacent dwelling units, to have widths as low as 16 feet while
allowing two-way traffic.As traffic volumes increase on neigh- 5.2b Urban nee-traditional standard.An urban standard
borhood streets, pavement widths also increase,just as streams will utilize curbs and gutters,though the gutter may be tied to a
widen downstream to accommodate increased water volumes.'`
a biofilcer or swale rather than an underground storm drain.Ac
In practice this generates a new class of street for very low traffic cording to an informational report published by the Institute of
volumes, referred to as"access"streets,which are below"local" Transportation Engineers (ITE), pavement widths for neo-tra-
street in the standard street hierarchy. ditional urban streets are typically from 26 co 30' wide with a
shared central moving lane, and parking permitted on one or
For example, an access street serving 50 single family homes both sides. Sidewalks are provided on at least one side of the
25 each side) with 50 foot width lots would require 1,250 lin- street, though usually preferable on both sides.29
ear feet of street ((50 sfh/2) x 50 ft = 1250). A 36 foot wide
street would cover 45,000 square feet, usually in impervious 5.2c Rural Standard. A rural standard can be used where
asphalt or concrete pavement.A 26 foot wide street would cover aesthetics and ocher factors permit, with curbs and gutters re
32,500 square feet, a reduction of 12,500 of impervious land placed by gravel shoulders, further reducing construction costs
coverage.Assuming street construction costs of$10 per square and improving opportunities for stormwater infiltration. The
foot, this reduction in pavement generates a $125,000 reduc- gravel shoulders are graded to form a drainage way,with oppor-
cion in development costs, or $2,500 per lot. This does not tunities for infiltration basins,ponding and landscaping.A nar-
account for added cost reductions in reduced need for drainage row two-lane paved roadway is provided, approximately 18 to
22 feet wide. Most of the time single vehicles use the center ofsystemsbecauseofsmallerimperviouslandcoverage. Even
greater reductions in pavement can be achieved if on-street park the paved roadway.When two cars are present moving in oppo
ing is not required on both sides the entire length of the street,
or if sidewalks are not required on both sides.
site directions,drivers reduce speeds and move towards the right
hand shoulder. Protection of the roadway edge and organiza-
tion of parking are two issues in rural street design. Roadway
0 Start at the Sauna—Residential Site Planning&Design Guidance Manual for Swrmwater Quality Protection
metal,wood,or concrete header
to protect roadway edge
parking on shoulder
5°,
5?„---:
16
gravel shoulder
two narrow moving
with swale and trees lanes
5.2c Access street: rural standard
36±% impervious land coverage
edge protection can be achieved by flush concrete bands, steel of 30 mph for most current municipal standards.30 This reduced
edge, or wood headers. Parking can be organized by bollards, design speed increases safety, particularly for pedestrians. Nev-
trees,or allowed to be informal.On very low volume,low speed, ertheless,shared moving space may promote unsafe conditions
access streets,sidewalks may not be required,as pedestrians walk or high incidences of driver inconvenience if traffic volumes are
in the street or on the shoulder. much above 500-750 ADT.On access streets where bicycle traffic
is especially high,such as designated bike routes or in university
The current typical municipal street standards that mandate 80 towns,wider streets may be advisable to provide adequate space.
to 100% impervious land coverage in the public right-of-way
are a principal contributor to the environmental degradation Emergency service providers often raise objections to reduced
caused by residential development. A street standard that al- street widths.Typical Fire Department standards require greater
r,1( lows a hierarchy of streets sized according to average daily traf- moving space for emergency access than accommodated by neo-
fic volumes yields a wide variety of benefits: improved safety traditional designs. A principal concern is that emergency ac-
from lower speeds and volumes,improved aesthetics from street cess may be blocked if a vehicle becomes stalled in the single
trees and green parkways, reduced impervious land coverage, moving lane. Grid street systems provide multiple alternate
less heat island effect, and lower development costs. If the re- emergency access routes to address this concern, though there
duction in street width is accompanied by a drainage system may be a marginal increase in response times. Documenting
that allows for infiltration of runoff, the impact of residential the number of instances where delay has occurred in existing
streets on stormwater quality can be greatly mitigated. pre-war neighborhoods with street widths below current Fire
Department standards may be a suitable way to asses the risk of
Street width considerations.The experience of both the pre-war this situation arising in new neighborhoods with neo-traditional
traditional streets and newer subdivisions of neo-traditional de- street design,and to balance it with the demonstrated increased
sign has shown that low volume streets with shared moving lanes risk from higher traffic speeds on wider streets.
4110 can be safe, often safer than wider streets, because drivers are
more cautious. These neo-traditional streets are designed for Emergency service access is one factor of many that form a gen-
traffic speeds between 15 to 25 mph,compared to a design speed eral assessment of neighborhood safety. Some ways to balance
Baa Arca>wrmwatcr Management Agencies Association
41
r .Details
5.2 Residential streets (continued)
0
cross-slope to curb
swale inlet
C"
J
At"
ac .
1 a
infiltration Swale/biofrlter
5.2d Urban curb/swale system
0 emergency service access with the benefits of access streets in-
clude: allowing parking on one side only to preserve a wider
moving space and requiring smoke alarms or sprinkler systems
to reduce fire hazards.
Hillside sites have special access concerns and fire risks. Because
of the potential of shared moving lanes to be blocked by a single
vehicle, with no comparable alternate route, reduced street
widths may not be advisable on long cul-de-sac streets or nar-
row hillside sites.
r ._ ,..
Street drainage. Current Bay Area municipal standards gen l
erally require concrete curb and gutter along both sides of a y•
residential street, regardless of number of houses served. The e4 rfi,; Y;r . 'curb and gutter serves several purposes: it collects stormwater f =f•"ii:
and directs it to underground conveyance drainage systems, it t14 ?
protects the pavement edge, it prevents vehicle trespass onto
the pedestrian space, it provides an edge against which street
sweepers can operate,and it helps to organize on-street parking.
For stormwater quality, curb and gutter systems act to collect Inlet detail for urban curb/swale system
and concentrate pollutants,providing a directly connected con- Just as a drop inlet collects runoff into an underground
duit to natural water bodies.There are rwo alternatives to typi- pipe system, a swale inlet collects runoff into a sur-
410 cal curb and gutter systems that meet functional requirements
while lessening the street's impact on stormwater quality.
face infiltration system.This swale inlet includes boul-
ders set in soil to dissipate flow velocities and mini-
mite erosion.
t' Start at th•Source-Rc>idential Sue Planning&Design Guidance.Manual hi,r Scurmwucr Qualm.Pruteaiun
r
culvert under intersections bollards or bollards and chain
optional for vehicle control)
curb at corners
vegetated Swale or
gravel shoulder
1.‘'
7---
7-..;:'•.:.:7:\\. ,A.\
7
5.2e Rural swale system
4)5.2d Urban curb/swale system. On streets where a more along its entire length, the buildup of pollutants in the soil is
urban character is desired, or where a rigid pavement edge is minimized. If parking is not desired on the shoulder, or if it
required, curb and gutter systems can be designed to empty needs to be organized, bollards, trees or groundcovers can be
into drainage swales.These swales can run parallel to the street, installed along the shoulder to prevent vehicle trespass.
in the parkway between the curb and the sidewalk,or can inter-
sect the street at cross angles, and run between residences, de—
pending on topography. Runoff travels along the gutter, but curb and gutters with underground drainage systems can be
instead of being emptied into a catch basin and underground
integrated into street design to create a headwaters street system
pipe, multiple openings in the curb direct runoff into surface
that minimizes impact on stormwater quality and that captures
swales or infiltration/detention basins.If planted with turfgrass
the most attractive elements of traditional neighborhood design.
and gently sloped,these swales function as biofilters(see Drain Street drainage considerations.The perception that surface swale
age systems 4.1c). Because concentration of flow will be high systems require a great deal of maintenance is a barrier to their
est at the curb opening,erosion control must be provided,which acceptance.In practice,maintenance is required for all drainage
may include a settlement basin for ease of debris removal. systems,and surface systems can require comparable or less main-
tenance than underground systems.Design factors for low main-
5.2e Rural swale systems. On streets where a more rural tenance include:
character is desired, concrete curb and gutter need not be re-
erosion
e _
erosion control at curb openings
quired. Since there is no hard edge to the street, the pavement
margins can be protected by a rigid header of steel,wood or a — shallow side slopes and flat bottoms (as opposed to ditches
concrete band poured flush with the street surface. Parking can which erode)
be permitted on a gravel shoulder.If the street is crowned in the —
planting with easily maintained groundcover such as turf
IP
middle, this gravel shoulder also can serve as a linear swale,
permitting infiltration of stormwater along its entire length. —minimizing weeds through proper plant selection or installa-
tion
runoff from the street is not concentrated,but dispersed tion of permeable landscape fabric.
i
i.'-- Bas Arca titurmssacrr\ianagrmrnt Agrnars.•1swua:.,41
1
1
Details
5.2 Residential streets (continued)
concave slope to center
r---
convex slope to gutterr
li 4 catch basin at high point
catch basin at low point
il • '';':,:..
l'... .„„„Jr/ : . •-. -,• 2.2..- ,-
A.. s
t" ..-
C.:-'4• •• .:—..''-
i; ,:.
1 /
i/ pollutants JJJ
y/ conveyed to outfall first flush runoff infiltrates into soil
Conventional median design: convex surface
5.2f Alternative concave median
0 Maintenance practices for surface systems are different than most landscaped swale or turf lined biofilter. Because of the relatively
urban Public Works Departments currently practice,and some small area provided by the median for stormwater infiltration
employee retraining may be required to facilitate maintenance and retention, a catch basin and underground storm drain sys-
of street systems using surface swales instead of concrete curbs tern may be required. By setting catch basin rim elevations just
and underground pipes. One advantage of surface drainage sys- below the pavement elevation, but above the flow line of the
tems is that problems, when they occur, are easy to fix because infiltration swale, a few inches of water will collect in the swale
they are visible and on the surface. before overflowing into the underground system.
Medians.Sometimes streets are designed with central medians •
to divide traffic for safety or aesthetics.
Conventional median design includes a convex surface ris-
design for medians.
ing above the pavement section,with drainage directed towards tea
a curb and gutter system. Runoff is conveyed rapidly off the ` -.
median and the street directly into a catch basin/underground cli•
pipe system,concentrating pollutants and carrying them to water s •'
bodies. J i s
5.2f Alternative concave median. If the soil level in the
I
median is designed as a concave surface slightly depressed be- A catch basin located at the low Like an overflow drain in a bath-
point of a conventional convex me- tub,a catch basin located just be-
low the pavement section, water is directed from the street into dian and gutter collects all runoff low the pavement surface, and a
the median.including the first flush. few inches above the flow line of a
concave median, provides an op-
oncave medians are especially valuable at creating the first porcunity to pond runoffwhile also
flush runoff which carries a hi h concentration of oils and ocher
providing drainage for larger
g storms.
pollutants off the street,especially if the median is designed as a
i
r, Start et the Source-Residential Site Planning&Design Guidance Manual for Scormwater Qualiry Protection
i
Details
5.6 Landscape
0
big trees mulch
4
I11Os,.....,
arsi
1 ' C—,r - "1\_
tr
deep rooted groundcover j
5.6a Plant selection and landscape maintenance
i
5.6 Landscape. In the natural landscape, most soils infiltrate A large number of plant species will survive moist soils or peri-
a high percentage of rainwater through a complex web of or- odic inundation.These plants provide a wide range of choices
ganic and biological activities that build soil porosity and per- for planted infiltration/detention basins and drainage swales.
meabiliry.Roots reach into the soil and separate particles of clay, Most inundated plants have a higher survival potential on well-
insects excavate voids in the soil mass, roots decay leaving net- drained alluvial soils than on fine-textured shallow soils or clays.
works of macropores, leaves fall and form a mulch over the soil Though oaks generally do not tolerate summer moisture, ma-
surface, and earthworms burrow and ingest organic detritus to cure valley and blue oaks (Quercus lobata and Q. douglasit) in
create richer, more porous soil.These are just a few examples of alluvial soils can survive winter inundation for up co 100 days
the natural processes that occur within the soil.
34 annually.35
In development, a certain amount of soil must be covered with Maintenance can have a significant impact on soil permeability
impervious surface,but the remaining landscape can be designed and its ability to support plant growth. Most plants concentrate
and maintained to maximize its natural permeability and infil- the majority of their small absorbing roots in the upper 6 inches
tration capacity. of the soil surface if the surface is protected by a mulch or forest
litter. If the soil is exposed or bare, it can become so hot that
5.6a Plant selection and landscape maintenance. The surface roots will not grow in the upper 8 to 10 inches. The
proper selection of plant materials can improve the infiltration common practice of removing all leaf litter and detritus with
potential of landscape areas. Deep rooted plants help co build leaf blowers creates a hard crusted soil surface of low permeabil-
soil porosity_Plant leaf-surface area helps co collect rainwater icy and high heat conduction. Proper mulching of the soil sur-
before it lands on the soil, especially in light rains, increasing face improves water retention and infiltration,while protecting
the overall water holding potential of the landscape. A single the surface root zone from temperature extremes.36
street tree can have a total leaf surface area of several hundred to
lipseveral thousand square feet,depending on species and size.This 5.6b Concave vegetated surfaces. Landscape surfaces are
above ground surface area created by trees and ocher plants greatly conventionally graded to have a slight convex slope.This causes
contributes to the water holdinicapacicv of the land. water to run off a central high point into a surrounding drain-
5y Start e1 the Source-R.dermal!tar Plann:ne\Deign Guidance Manual for lrortnwater Qualm Prutccuon
il . i ' WO yl Ci- Aefro&ch ,
Through the reduction of much of the proposed of curb and gutter,
much of the existing roadway profiles can be maintained with little impact to the
adjacent right of waY. This will save a significant amount of the existing trees.
11111,4fi k.
6(1j-el??
8 )
q93
Through the reduction of much of the proposed of curb and gutter,the
i`
1:e-
eil
ThA 64' number of cross drains and their associated cost is also greatly reduced.
Assuming the tailwater elevation can be reduced as anticipated,the pipe
sizes proposed in the current collection system design can be reduced significantly
1 t
c'*thereby realizing a significant savings to the City.
I frti r .
t
oac"\ .
Conflict manholes are expensive to construct,hydraulicly inferior and
are a potential maintenance item and should be avoided. Through the reduction
C in the number of cross drains, the reduction in the size of the collection system
and some sound value engineering the number of conflict manholes currently
proposed can be significantly reduced.
IInnovative Approaches
Innovative approaches which are a trademark of Aikenhead&Odom;and which
I will increase the teams ability to accomplish the project goals while at the same
time saving the City substantial short and long term dollars,should be noted as
follows:
11 Through experience gained from our recent similar projects, the
Aikenhead&Odom Team already has a project knowlege that will enable us to
140 develop innovative stormwater management alternatives that will provide a
significant cost savings to the City. Also,our familiarity with the drainage history
of this area will prove to be an invaluable asset to the Aikenhead & Odom
Design team during the design development of this project.
Aikenhead & Odom will use our substantial permitting experience to
I minimize regulatory requirement impacts on the project to the maximum extent
possible. We will maximize the use of existing soils conditions, will use the
concept of"mitigating treatment'wherever feasible,and will utilize our familiarity
with the drainage characteristics of the basin to minimize stormwater treatment
facility requirements to every extent possible.
Aikenhead&Odom will use our extensive public involvement experience
and computer graphic capabilities to assist the City in preparing for,and holding,
town meetings. This experience has proven invaluable on past projects to allow
the public to"buy in"to the project at its conception,thereby greatly reducing
opposition that could possibly impede the project design development.
Aikenhead & Odom will use our substantial drainage and permitting
regulatory experience for the maximum design and construction efficiency. We
investigate stormwater treatment alternatives whc,ever acquisition requirements
may prove prohibitive, either due to cost or public relations issues. Routine
familiarity with the regulatory agency personnel and regulations assures the
Department of Public Works that our design will result in a"best fit" between
construction efficiency and design perm ittability.
I
11
Elimination of the proposed(ETM Design)curb and gutter on 1'through
II12th streets, Ahern Street, Country Club Lane and Sherry Drive will have the
single most significant impact on the project. By eliminating the curb and gutter,
101) Pr I
the requirements for stormwater treatment are significantly reduced. Gentlea
swales could be used to collect the runoff and discharge into a series of collectionk.--'-'\
boxes that would eventually outfall directly into the Selva Marina Lagoon.
0(Aoln\
f f1\
k
Each of the above mentioned collection boxes could be designed as
s 6. sedimentation traps thereby reducing the loading on the lagoon. These boxes
n('o p°could be fitted with baffles that collect the sedimentation for later removal and
IJ
disposal. Although a fairly significant maintenance item,these boxes work well
in reducing the sediment loading on the downstream outfall.
1 By reducing the treatment requirements through the elimination of most
of the proposed curb & gutter sections, the proposed Howell Park collection
basin could be eliminated all together and thus the existing park can remain as it
currently exists.
Although significantly reduced,there will be some stormwater treatment
I requirements for this project. An esthetically pleasing and relatively cost effective
alternative for meeting these requirements involves the use of Preben Johansen
Park, but not as currently proposed in the ETM design? This alternative is
Isummarized as follows:
Remove and store all of the significant Palm trees currently
located within the park. These tress will be replanted in their approximate
Icurrent location after the improvements have been made.
q Grade the entire park toward the center at a gentle 10:I slope
Elthereby creating a large swale in the north/south direction.The park will
then be able to retain the required amount of runoff to meet treatment
requirements.
I 4 Construct a large underdrain system running the entire length of
and down the center of the swale. A stormwater pumping system will
then be constructed at the northern end of the park;and connected to
this underdrain piping to help it draw down in a short period of time,
thereby returning the park to it's current useable state within hours of a
Irainfall event.
Once the construction is complete the entire park will be grassed,
the Palm trees replanted and the park will look similar to its current
condition. The only period of time that its use will be limited will be
during and shortly after a rainfall event.
Aikenhead & Odom has successfully used the pumped filter design
technique on several occasions. In this application, it would provide a
cost effective,relatively low maintenance intensive alternative that would
not destroy the integrity of the park or its surrounding area.