----Original Message Follows----
From: "Erwin Hayer" <eeh625@hotmail.com>
To: Hannah.F.Hadley@usace.army.mil
CC: Charles.C.Rairdan@usace.army.mil, Carl.E.Korman@usace.army.mil, 
kreinbergg@saccounty.net, ziebronk@saccounty.net
Subject: MAGPIE CREEK DIVERSION CHANNEL
Date: Sat, 31 Jan 2004 22:51:32 -0800


   31 January 2004
   Hannah F. Hadley
   Environmental Manager
   US Army Corps of Engineers, Environmental Planning Section
   1325 J Street
   Sacramento, CA 95814-22-922

Subject: MAGPIE CREEK DIVERSION CHANNEL LEVEE HEIGHTS, FLOWS AND DETENTION 
AREA.

   Reference No 1: Draft Supplemental Report to the Section 205 Final 
Detailed Project Report and Environmental Assessment on Magpie Creek, 
California, dated January 2004 by USACE.

   Reference No 2: Section 205 Final Detailed Project and Final 
Environmental Impact Statement/Environmental Impact Report for Magpie Creek, 
California, dated April 1996 and Supplemental Report, dated August 1997, by 
USACE.

   Reference No 3: The Sacramento Area Flood Control Agency (SAFCA) Initial 
Study/Proposed Mitigated Negative Declaration for the Magpie Creek Flood 
Control Project, dated 13 March 2002.


   Dear Hannah Hadley

SAFCA Ref. No 3, page 2-4, paragraph 2-4, states:
"The objective of this project is to increase the level of flood protection 
to properties along historic Magpie Creek to about a 170-year level from 
flood waters originating east of Raley Boulevard.  USACE has determined that 
170-year protection is the optimum level of flood protection based on its 
cost/benefit analysis."

SAFCA Ref. No 3, page 2-6, top paragraph states:
"The floodwall would begin just down stream from Raley Boulevard and 
continue to about 100 feet south of the Vinci Avenue Bridge.  The average 
height of the floodwall would be 2 feet above the existing grade." - snip -

SAFCA Ref. No 3, page 2-8, middle of top paragraph states:
- snip - "During a 170-year event, the increase in water surface is 
projected to be 0.5 feet at Raley Boulevard and 0.1 feet at the western 
boundary of McClellan Business Park.  This would increase the inundated area 
to 78 acres." - snip -

My questions of 18 March 2002 and SAFCAs Answer of 19 March 2002 are below.

"Q. How deep is the floodwater on Raley Boulevard when the current MCDC 
levee is overtopped?
A. About 2.1 feet."

"Q. How many vertical feet of new floodwall would be above the floodwater 
elevation during a 170-year event?
A. While the final design of the floodwall has not been determined, the 
proposed top of the new levee and floodwall are set at the expected 170-year 
flood elevation."

MY COMMENTS on SAFCAs ANSWER ABOVE:
The above answers did not agree with the 2 feet rise of the floodwall and 
the 0.5 feet rise of floodwater at Raley Boulevard.  If the 170-year 
floodwater reached the top of the proposed 2 feet rise in the floodwall, 
then I would expect to see a about a 2 feet rise in the floodwater at Raley 
Boulevard to 4.1 feet deep.

USACE Ref. No 1, page III-8, paragraph heading "NATURAL FLOOD DETENTION 
BASIN AND LEVEE ALTERNATIVE" has the following sub-paragraph statements:

"LEVEE RAISING.  The existing left bank levee of the MCDC is raised up to a 
maximum of 5 feet in height for a distance of 2100 feet.  The proposed 
raised levee begins just downstream from Raley Boulevard to just upstream of 
Vinci Avenue." - snip -

"FLOODING OF EXISTING FLOOD PLAIN.  The area at 76.5 acres would be 
inundated by the 250-year event.  The computed increase in water surface is 
approximately 0.7 feet at Raley Boulevard and 0.2 feet at the western 
boundary of McClellan Business Park.  The inundated land would be acquired 
and preserved as flood plain areas.  The flood plain for the 250-year event 
is shown on Figure 6 on Attachment 1 of Enclosure B."

USACE Ref. No 1, Chapter V - SELECTED PLAN, Page V-1 indicates:
The USACE Top of Levee elevation at Raley Boulevard is proposed as 49.91 
NGVD, at station 66+00 west of Raley Boulevard as 49.25 feet and 48.75 feet 
NGVD near Vinci Avenue.

USACE Ref. No 1 Cover Picture of a White Van on Raley Boulevard just south 
of Magpie Creek on 3 February 1998 and the depth was estimated as 2.5 feet 
on the road.


MY COMMENTS on the SAFCA and USACE DOCUMENTS:
SAFCA Ref. No 1 indicates 78 acres would be inundated during a 170-year 
flood event.  USACE Ref No 1 indicates 76.5 acres would be inundated during 
a 250-year flood event in the above paragraph, but the reference to figure 6 
(by Engineering, Hydraulic Design) is questionable as the figure 6 is 
estimated as a 200-year event.  The same map, Figure 4 of Enclosure A (by 
Environmental Resources Branch) identifies the map as the Estimated 250-Year 
Flood Inundation.  It is getting difficult to understand what the USACE is 
proposing.

SAFCA Ref. No 3, 170-year Floodplain East of MCDC With and Without Project 
(Exhibit 5), the USACE Engineering Branch Estimated 200-year flood event, 
Figure 6, Attachment 1, Enclosure B, and the USACE Estimated 250-year flood 
inundation, Figure 4, of USACE Draft Environmental Assessment, Jan 2004.  
All 3 of the documents/maps, 170-year, 200-year, and 250-year look 
identical.

MY QUESTIONS ON THE ABOVE LEVEE and FLOODPLAIN EAST of the MCDC INFORMATION:

1.  Is NGVD the same as MSL (Mean Sea Level) and what does NGVD stand for?

2.  Do the different branches or sections working on the same project within 
the USACE talk or coordinate with each other on the documents that the USACE 
publishes?  (170-year, 200-year and 250-year Floodplain East of MCDC)

3.  What is the correct information on levee height and flood levels on 
Raley Boulevard?  (170, 200, 250-year events)

4.  Who and what documents are more accurate, SAFCA or USACE?

5.  Why is the USACE proposing to raise the levee a maximum of 5 feet when 
SAFCA was proposing a raise of approximately 2 feet and the Floodplain East 
of the MCDC is the same?

6.  Why does USACE want an additional 3 feet of levee height?

7.  Did the floodwater overtop the MCDC levee during the storm of 3 February 
1998?


THE MCDC FLOODWATER FLOWS.

The USACE Jan 2004 DSR, Chapter II - Study area, Hydrology does not mention 
any thing about flows down stream of Raley Boulevard.  The cfs in the MCDC 
existing conditiond, Table 3 of Attachment 1 of Enclosure B of USACE Ref No 
1 does not agree with the data in the USACE ref. No 2.  In Table 4, Project 
conditions, the cfs for MCDC is listed as 0 (Zero) for 2. 5, 10, 25, 50, 
100, 200, and 500-year events.  This is another instance that the USACE is 
confusing the facts.

More of my questions of 18 March 2002 and SAFCAs Answer of 19 March 2002 are 
below.

Q. What is the cubic feet per second flood flow at Vinci Avenue during a 
170-year storm event under current pre-project conditions?
A. The current 170-year pre-project peak flow at Vinci Avenue is about 1,485 
cfs.

Q. What is the cubic feet per second flood flow at Vinci Avenue during a 
170-year storm event after the project is completed?
A. The projected post-project peak flow at Vinci Avenue is about 1,750 cfs.

Q. What is the current cross section in square feet of the area under the 
bridge at Robla Creek and the SNRR Bike Trail that floodwater would flow on 
down the channel?
A. The existing bridge opening has an area of 428 sf.


MY COMMENTS ON THE MCDC FLOODWATER FLOWS:
The USACE indicated the flow in the MCDC would be 1100 cfs for a 50-year, 
100-year, 200-year, and 500-year event for pre project conditions.  
Reference USACE April 1996 FDPR Appendices, Table 2.  The USACE in Table 4 
also indicates the existing channel capacity down stream of Dry Creek Road 
as 950 cfs.

SAFCA indicates the flow under current pre project conditions as 1,485 cfs.  
After project the flow will increase to 1,750 cfs for a 170-year event.  
During the Robla Creek South Levee Project during the summer of 2002, SAFCA 
had the contractor remove a large amount of soil from the north side of the 
MCDC, down stream of Dry Creek Road.  This would increase the flow capacity 
of this section that the USACE stated the existing channel capacity was 950 
cfs.

What I am trying to understand is how can 1.750 cfs flow in a channel that 
the USACE indicates has only 1,100 cfs capacity and downstream of Dry Creek 
Road the capacity is reduced to 950 cfs?  I believe the USACE data to be 
false.

In particular because the USACE wants to reduce SAFCAs recommended 150 
square feet box culverts at the Bike Trail to 75 square feet.  The MCDC was 
constructed about 1955 and the 428 square feet opening at Robla Creek was 
not enlarged.  This caused major increases in flooding east of the SNRR and 
north of the MCDC south levee.  THE RIO LINDA AIRPORT RUNWAY WAS RAISED AT 
THE SOUTH END 6 FEET, FROM ABOUT 36.0 TO 42.0 FEET MSL, TO GET THE RUNWAY 
ABOVE THE INCREASED FLOODING CAUSED BY THE USACE 1955 MCDC PROJECT.

SAFCA purchased and removed 8 homes located at 5549 Dry Creek Road, 5549 Dry 
Creek Road, 5701 Dry Creek Road, 1030 Ascot Avenue, 1032 Ascot Avenue, 1130 
Ascot Avenue, 1132A Ascot Avenue, and 1132B Ascot Avenue.  Floor elevations 
ranged from 42.41 to 44.39 feet msl.  SAFCA decided it was cheaper to 
purchase and remove the 8 home than to try and flood protect them from the 
storm waters from Robla Creek and Magpie Creek Diversion Channel when the 
Robla Creek South Levee was raised during the summer of 2002.  This levee 
raising was required for additional protection of the north Sacramento area, 
which had been placed at a increased flood risk because of the raising of 
the west levee of the NEMDC, now Steelhead Creek.  This levee raising was 
required for the flood protection of the Natomas area that allowed 
construction in Natomas area with no requirement to purchase flood 
insurance.

Some homes north of Ascot on Dry Creek Road have floor elevations as low as 
44.38 feet msl and are not protected by any levees mentioned above.  I hope 
this project does not increase the floodwater at these homes.

I believe the SAFCA information is more accurate than the USACE information. 
  Both indicated they were using David Ford Consulting Engineer's data.


MY QUESTION ON INCREASED STORM WATER FLOWS IN THE MCDC:

8.  Is this problem of increase flows going to cause more flooding north of 
the MCDC in Rio Linda area?

9.  Can anyone give me reasonably accurate answers to the above 8 questions 
that I have numbered?

Sincerely

Erwin E. Hayer
950 G Street
Rio Linda, CA 95673

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