HomeMy WebLinkAboutLetter from Rodney Burrows 1.07.09To: John Niewoehner From: Rodney Burrows, PE Enserca Engineering, LLC. Date: January 7,2009 RE: ETC Canyon Pipeline LLC: (1) Rulison to Enterprise Pipeline Development Plan and (2) Holmes
Mesa Compressor Station SUBJECT: Response to County Review Comments •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• Mr. Niewoehner Thanks for reviewing the
drawings we submitted for the ETC project above, and for sending us your review comments. Our responses to your comments are included below, following your comments depicted in bold
type. A response of 'OK' means we agree with the comment and have incorporated your directions into the drawings. Unfortunately, a preliminary grading plan produced by River City Consultants
was inadvertently included in the package. That drawing has been superceded by the one I stamped dated 11-24-08. Stamped drawings with today's date incorporating your comments are attached.
Rulison to Enterprise Pipeline Development Plan 1. Directional Boring Under the River and Highway: The Enserca engineering drawing AL-OS shows a single boring under the both the highway
and river. However, on Enserca drawing EX-01 there are two borings --one boring under the highway and a second boring under the river. Which is correct? We propose to complete the crossings
as two separate bores. 2. Reclamation Plan: Steve Anthony needs to review the submitted reclamation plan. The County has a one-page document that lists the requirements of the reclamation
plan. OK. 3. Financial Security for Reclamation: In order to calculate the amount of the financial security, we need to determine the area that will be disturbed by the pipeline. Roughly
this area is the ROW width multiplied by the pipeline length [i.e. 60' ROW x (53000' pipeline -3200' boring) = 66 acres]. Typically, the financial security required for pipeline projects
is $2,500 per acre. OK. Holmes Mesa Compressor Station SUP 1. Grading -Proposed Fill and Cut Slopes: The grading plan created by River City Consultants shows 3:1 slopes and does notshow
the retention basin. The grading plan created by Rodney Burrows shows 2:1 slopes. Which plan is correct? The County may require 3:1 slopes since vegetation cannot be readily re-established
on 2:1 slopes. The River City drawing was preliminary and sent to you by mistake. Please use the drawing created by Rodney Burrows. Our preference is for 2:1 slopes, and we figured
we would armor the slopes with 3"-rock/gravel in the area immediately around the compressor pad per phone discussion with John Niewoehner on January 7,2009. 2. Grading -Drainage Swales:
How will runoff be directed from the compressor platform to the retention basin? No swales directing runoff to the retention basin are shown on the grading plan. We add some notes and
arrows showing swales directing the runoff to the retention basin. A diversion ditch swale detail is provided on sheet CV-OB. A revised copy of the grading plan (CV-04, rev 2 dated January
7,2009) is attached. 3. Grading -Vehicle Access: The grading does not show driveways interconnecting the different platform levels. Although the perimeter road may not be shown on River
City's drawing, our drawing shows a perimeter road around the compressor site interconnecting each of the three flat pad levels. 4. Retention Basin: What is the volume of the proposed
retention basin? What volume is required to retain the 1 OO-year storm? How will the basin empty between rainfall events? What design elements prevent the failure of the retention basin?
Who will maintain and clean the basin? Per our calculations (attached) a 1 OO-year storm will create approximately 93,200 cubic feet of runoff. We sized the basin to contain 93,200 cubic
feet. For environmental reasons, we would prefer the basin to retain all runoff until a plant operator can verify that no contaminants have inadvertently entered the stormwater. After
that, the runoff can be removed by vacuum truck, if contaminated, or allowed to percolate andlor evaporate if uncontaminated. We will install a concrete spillway to allow flows greater
than the 1 ~O-year flow to pass over the spillway. We have oversized the earth berm to include more than 3 feet of freeboard above the top level of retained water. 5. Reclamation Plan:
Steve Anthony needs to review the submitted reclamation plan. OK. 6. Financial Security for Reclamation: We need two reclamation bonds for the compressor station. The first bond is for
re-vegetating the cut and fill slopes created during the construction of the compressor platform. The second bond is for the re-grading and re-vegetation of the compressor site when
the compressor station is abandoned. This second long-term bond should not have an expiration date and its dollar amount should take into account inflation. OK. 7. Engineer's wet seal:
The grading and drainage plans and report needs to have the wet seal of the professional engineer. A scanned or photocopied seal is not sufficient. OK.
' .. Thanks again for your help. Sincerely, ~ Rodney D. Burrows, PE Enserca Engineering, LLC. 165 South Union Blvd., #1000 Lakewood, CO 80228 303-468-2700 EXP DATE 07-31 -10