Parks Comm PKT 01-08-2015H U [TT AOLLARS
HUITT- ZOLLARS, INC. 1 818 Stewart Street i Suite 1120 1 Seattle, WA 98101 -1479 1 206.324.5500 phone t 206.328.1880 tax i hula- zoRam.com
Memorandum
DATE:
January 7, 2015
TO:
Steve Ikerd, Parks Deputy Director
FROM:
Matt Fewins, PE
SUBJECT:
Panther Lake Trail: Construction Cost Reduction Options
This memorandum presents potential design adjustments that may reduce construction costs
for the Panther Lake Trail Project.
Per the Huitt - Zollars /Federal Way meeting on October 2, 2014, some project items from the
April 4, 2014 Engineer's Opinion of Probable Construction Cost (see Attachment A), were
identified as having potential to be adjusted, thereby reducing construction cost.
Design Adjustments
Trail on berm — base course section depth:
Modify the berm trail section to show 2" existing organic removal from the top of the
existing berm and 2" new CSBC addition, instead of the previously shown 4" removal
and 4" addition. Berm trail sections are located from station 105 +00 to 114 +65, and
118 +65 to 120 +32.
ii. Remove gravel borrow from trail section:
Modify the trail section to remove the 12" of gravel borrow (driveway and parking lot
borrow sections to remain). This assumes that subgrade can /will be compacted per
geotechnical recommendation. The locations of gravel borrow removal are from the BPA
Trail at the SW Campus Drive frontage to station 105 +00, station 114 +65 to 118 +65,
and station 120 +32 to 138 +15.
iii. Minimize pit run import material for trail embankment fill:
Modify the trail embankment design to use on -site materials as embankment fill. Include
pit run import material only in the case of trail embankment fill quantity exceeding project
site embankment material cut quantity (exclusive of organic duff).
iv. Revise mitigation soil amendment quantities:
Mitigation soil treatment was reviewed and revised where practical. Removed imported
topsoil and supplemented a portion with additional compost.
Items i through iii may affect the strength and durability of the trail subgrade, base and
pavement. Item iv may affect plant performance of the mitigation improvements. These
changes were incorporated into the January 7, 2015 Engineer's Opinion of Probable
Construction Cost (see Attachment B). The following summarizes the two Engineer's Opinion of
Probable Construction Cost (OPC):
HUITT:Z UMS
OPC Date
Total Cost
April 4, 2014
$1,290,000
January 7, 2015
$915,000
Reduction
($375,000)
In addition to these design adjustments, costs associated with the reduction of the parking lot
sizes were also reviewed:
Parking Lot Alternates
Huitt - Zollars is providing a review of two parking lot alternatives for the currently designed
parking lot (baseline) (see Attachment C for exhibits) and the associated OPCs (see
Attachments D & E):
a. Baseline
Parking lot, per previously submitted plans (40 stalls).
b. Alternative 1
Reduced parking lot with approximately half of the stalls of the baseline parking lot.
c. Alternative 2
Reduced parking lot, to be outside of the 200 ft wetland buffer.
For each parking lot alternate, grading, paving, storm drainage and mitigation costs were
reviewed to estimate potential reductions to overall engineer's opinion of probable cost
compared to the baseline parking lot (no changes were made to the driveway entry):
Parking Lot Design
OPC
Difference from Baseline
Baseline (January 7, 2015)-40 Parking Stalls
$915,000
- - - --
Parking Alternate 1 — 21 Parking Stalls
$860,000
$55,000
Parking Alternate 2 — 15 Parking Stalls
$845,000
$70,000
Notes:
HURT - MLLNBS
1. Stormwater system: Due to stormwater system still being under design (by the City),
the stormwater cost for the alternates may vary depending on the final design.
2. Mitigation: Currently, the plans call for clearing and grading the park area south of the
proposed trail and hydroseeding non -paved areas. Since mitigation for hydroseeding
disturbed areas within the wetland buffer is the same as mitigating for paving disturbed
areas within the buffer, there is anticipated to be little to no mitigation reduction for the
parking alternates. However, due to the open area west of the parking lot being larger in
the parking alternates, there is potential for:
a. Leaving a portion of the open area as existing to reduce mitigation requirements.
b. Use the open area as a mitigation area to reduce mitigation in other areas of the
park.
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1 lUrrr"2DLLARS
818 Stewart Street, Suite 1120
Seattle, Washington, 98101
Phone(206)324 -5500 Fax(206)328 -1880
PANTHER LAKE OPEN SPACE
ATTACHMENT C
PARKING LOT BASELINE (38 STALLS + 2 ADA)
2015.01.06
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SCALE (IN FEET)
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818 Stewart Street, Suite 1120
Seattle, Washington, 98101
Phone(206)324 -5500 Fax(206)328 -1880
PANTHER LAKE OPEN SPACE
ATTACHMENT C
PARKING LOT BASELINE (38 STALLS + 2 ADA)
2015.01.06
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ATTACHMENT C
818 Stewart Street, Suite 1120 PARKING LOT ALTERNATE 1 (19 STALLS + 2 ADA)
Seattle, Washington, 98101 2015.01.06
Phone(206)324 -5500 Fax(206)328 -1680
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818 Stewart Street, Suite 1120
Seattle, Washington, 98101
Phone (206) 3245500 Fax (206) 328 -1880
PANTHER LAKE OPEN SPACE
ATTACHMENT C
PARKING LOT ALTERNATE 2 (13 STALLS + 2 ADA)
2015.01.06
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